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A colloidal synthesis protocol is demonstrated for InAs@InP core@shell quantum dots (QDs) with a tunable InP shell thickness (ranging from 3 to 8 monolayers), utilizing tris(diethylamino)‐arsine and ‐phosphine. Structural analysis reveals that the InP shell preferentially grows onto the tetrahedral InAs cores along the <‐1‐1‐1> directions, forming tetrapodal‐shaped InAs@InP QDs. Growth of the InP shell causes a red shift in the absorption spectrum of the QDs. This is explained by considering that electrons are delocalized throughout the whole core@shell QDs, while holes preferentially leak along the <‐1‐1‐1> directions, as indicated by the density functional theory calculations. This means such heterostructures cannot be described as type‐I or quasi type‐II, contrary to earlier assumptions. The overlap of carrier wavefunctions throughout the entire InAs@InP QD structure results in no significant reduction of the Auger recombination rate, which remains as fast as in InAs QDs. However, the InP shell enhances photoluminescence (PL) efficiency (up to ≈13%) by passivating surface trap states of the InAs QDs (mainly located close to the top of the valence band). The overgrowth of a ZnSe shell endows the QDs with a high PL efficiency (≈55%) and good stability upon air exposure (≈80% PL intensity retention after 14 days). [ABSTRACT FROM AUTHOR]

Indium phosphide (InP) is emerging as a viable and environmentally friendly alternative to toxic cadmium‐based quantum dots (QDs), especially in the fields of lighting and display. This is owing to similar material properties of InP to those of commercial Cd‐based QDs. Nonetheless, the surface quality of InP needs enhancement through a post‐treatment process to eliminate surface oxides, typically with hydrofluoric acid (HF). The challenge arises with smaller, such as green InP QDs, as HF easily over‐etch the InP cores, thus leading to an unpredictable size distribution and reduced production consistency. This research introduces a refined synthetic strategy that circumvents this over‐etching phenomenon and offers a more precise control over the etching process of smaller InP QDs. By applying an additional protective layer to the InP cores prior to etching and employing ammonium fluoride (NH4F) as an alternative to the conventional HF, the over‐etching incidence can be markedly mitigated. The results reveal that smaller InP/ZnSeS QDs with photoluminescence quantum yield (QY) >90% can be consistently produced, thereby proposing a more efficient and safer method for the fabrication of smaller InP QDs. [ABSTRACT FROM AUTHOR]

The current efficiency records for generating green hydrogen via solar water splitting are held by indium phosphide (InP)‐based photo‐absorbers, protected by TiO2 layers grown through atomic layer deposition (ALD). InP is also a leading material for photonic integrated circuits and computing, where ultrafast near‐surface behavior is key. A previous study described electronic pathways at the phosphorus‐rich (P‐rich) surface of p‐doped InP(100) using time‐resolved two‐photon photoemission (tr‐2PPE) spectroscopy. Here, the intricate electron pathways of the P‐rich InP surface modified with ALD‐deposited TiO2 are explored. Photoexcited bulk InP electrons migrate through a bulk‐to‐surface transition cluster of states and surface states and inject into the TiO2 conduction band (CB). Energy levels and occupation dynamics of CB states in P‐rich InP and TiO2 adlayers are observed, with discrete states preserved up to 10 nm TiO2 deposition. Thermalization lifetimes of excited electrons > 0.8 eV above the InP conduction band minimum (CBM) are preserved for layer thicknesses up to 2.5 nm. Annealing at 300 °C to achieve crystalline TiO2 reconstructions destroys interfacial states, affecting charge transfer. These observations enable innovative engineering of the P‐rich InP/TiO2 heterointerface, opening new possibilities for studying hot‐carrier extraction, adsorbate effects, surface plasmons, and improving photovoltaic and PEC water‐splitting devices. [ABSTRACT FROM AUTHOR]

Recent studies on top‐emitting structure, which is designed to enhance the color purity and outcoupling efficiency of quantum‐dot light‐emitting diodes (QLEDs), employ commercially unviable methods owing to limited options for applying the hole injection layer through solution processes on the bottom electrode. In this study, all‐solution‐processable conventional top‐emitting QLEDs (TQLEDs) are successfully fabricated by introducing a polyethylenimine (PEI) interlayer, doping isopropyl alcohol (IPA) into the hole‐injection layer (poly (3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate), PEDOT:PSS), and using the dynamic spin‐coating method. The increased hole injection resulting from the tuned anode‐HIL interface by the PEI and IPA‐doped HIL, coupled with the enhanced outcoupling efficiency and full width at half maximum (FWHM) derived from the optimized cavity length through simulation, realizes a red InP QLED with high efficiency and color purity. The optimized TQLED exhibits a maximum current efficiency and FWHM of 28.04 cd A−1 and 36 nm, respectively, which are threefold higher and 8 nm narrower than those of bottom‐emitting QLEDs, marking the highest current efficiency ever reported for top‐emitting red InP QLEDs. [ABSTRACT FROM AUTHOR]

Air quality is deteriorating due to continuing urbanization and industrialization. In particular, nitrogen dioxide (NO2) is a biologically and environmentally hazardous byproduct from fuel combustion that is ubiquitous in urban life. To address this issue, we report a high‐performance flexible indium phosphide nanomembrane NO2 sensor for real‐time air quality monitoring. An ultralow limit of detection of ~200 ppt and a fast response have been achieved with this device by optimizing the film thickness and doping concentration during indium phosphide epitaxy. By varying the film thickness, a dynamic range of values for NO2 detection from parts per trillion (ppt) to parts per million (ppm) level have also been demonstrated under low bias voltage and at room temperature without additional light activation. Flexibility measurements show an adequately stable response after repeated bending. On‐site testing of the sensor in a residential kitchen shows that NO2 concentration from the gas stove emission could exceed the NO2 Time Weighted Average limit, i.e., 200 ppb, highlighting the significance of real‐time monitoring. Critically, the indium phosphide nanomembrane sensor element cost is estimated at <0.1 US$ due to the miniatured size, nanoscale thickness, and ease of fabrication. With these superior performance characteristics, low cost, and real‐world applicability, our indium phosphide nanomembrane sensors offer a promising solution for a variety of air quality monitoring applications. [ABSTRACT FROM AUTHOR]

High‐power optical transmission (HPOT) technology has emerged as a promising alternative among far‐field wireless power transmission approaches, enabling the transfer of kilowatts of power over kilometer‐scale distances. Its exceptional adaptability allows operation in challenging scenarios where traditional electrical wiring is impractical or unfeasible, thereby opening up a vast array of potential applications previously considered utopian. An important pending assignment in enhancing the performance of laser‐based HPOT systems is achieving efficient photovoltaic conversion of high power densities (≥10 W cm−2). In this sense, there is a pressing need for the advancement of optical photovoltaic converters (OPCs) capable of enduring intense monochromatic irradiances. This work presents the design optimization, manufacturing, and characterization processes of a gallium indium phosphide (GaInP)‐based OPC under varying 637 nm laser power at room temperature. In addition, methods to evaluate the impact of temperature on performance are provided. The findings reveal a maximum efficiency of 53.5% at 10 W cm−2, surpassing literature results for GaInP converters by over 9%abs at those light intensities. Remarkably, this device withstands unmatched irradiances within GaInP OPCs up to 60 W cm−2, maintaining 42.3% efficiency. This study aims to push forward the development of wide‐bandgap power converters with recordbreaking efficiencies paving the way for new applications. [ABSTRACT FROM AUTHOR]

Next‐generation "Beyond 5G (B5G)/6G" wireless network systems have been researched and developed for meeting the rapid growth of mobile traffic. A high‐yield fabrication process of InP‐based transistors and tera‐hertz monolithic integrated circuits with 300 GHz operation is reported, which is a candidate frequency for "Beyond 5G/6G" network systems. The main focus is on a high‐yield and reproductive fabrication process of InP‐based high electron mobility transistors (HEMTs) while revisiting previous studies. The DC and radio frequency characteristics of fabricated InP‐HEMTs from the viewpoint of integrating circuits are described. Then, high‐frequency performances of ft = 280 GHz and fmax = 860 GHz in the bias conditions of Vgs/Vds = 0.2/1.1 V with good uniformity are obtained. Finally, InP‐based 300 GHz‐band mixer and power amplifiers are introduced, to which a backside process is also applied for ensuring their stability and enhancing output power. [ABSTRACT FROM AUTHOR]

Optical frequency combs (OFCs) have evolved into one of the most active areas of photonics, underpinning advancements in both fundamental science and commercial contexts. Electro‐optic modulation for OFC generation offers excellent versatility, stability, and phase coherence. With the rapid progress in micro‐nano fabrication techniques, electro‐optic frequency combs (EOFCs) have been realized on many integrated platforms, including silicon on insulator (SOI), indium phosphide (InP), and lithium niobate on insulator (LNOI). These compact, low‐cost, and energy‐efficient EOFCs support a wide range of applications. In this study, we review the theory for the generation of integrated EOFCs, summarize the demonstrations on the main integrated platforms, present applications, and envision the development directions of integrated EOFCs in view of materials, devices, and applications. [ABSTRACT FROM AUTHOR]

Understanding high‐order biexciton dynamics is important for the use of semiconductor quantum dots (QDs) in optoelectronic devices. The core–shell structure can be used to modulate biexciton dynamics by varying the shell thickness and core–shell energy band alignment. In this study, the biexciton dynamics in an unconventional case in which each QD is encapsulated by a submonolayer shell are demonstrated. The result of a transient absorption spectroscopic study shows that InP/ZnS core/shell QDs with submonolayer shell coverage exhibit a prolonged Auger lifetime. However, the QD size dependence of the Auger recombination time features two constant distinct stages instead of the typical monotonic volume scaling law in conventional QDs. It is attributed to the tradeoff between the enlarged QD size and quantum‐well confinement for the Auger processes. However, the abrupt change between the two stages is due to the change in the shell coverage. This study provides a reference for the application of core–shell QDs in optoelectronic devices in which full coverage of the shell is not achieved. [ABSTRACT FROM AUTHOR]

Indium phosphide (InP) quantum‐dot light‐emitting diodes (QLEDs) are considered as one of the most promising candidates for emerging displays owing to their good luminous performance and environmentally friendly properties. The operation of green InP QLEDs relies on the radiative recombination of electrically generated excitons, as in most QLEDs; however, the electrons injected into green InP QLEDs can easily pass through the quantum‐dot (QD) layer, resulting in a carrier imbalance and low external quantum efficiency (EQE). Herein, the mechanism of electron leakage in green InP QLEDs is revealed. Based on comparative experiments and simulations of the carrier concentration distribution, the path of electron leakage is determined and it is found that the root cause is the large Fermi energy difference between green InP QDs and indium tin oxide (ITO). To solve this problem, an ultrathin LiF layer is applied to modify the work function of the ITO, which simultaneously hinders electron leakage and enhances hole injection. Benefiting from a more balanced carrier injection, the maximum EQE of green InP QLEDs improves from 4.70% to 9.14%. In these findings, a universal mechanism is provided for hindering electron leakage in green InP QLEDs, indicating the feasibility of developing highly efficient green InP QLEDs. [ABSTRACT FROM AUTHOR]

Biomanufacturing of ethylene is particularly important for modern society. Cyanobacterial cells are able to photosynthesize various valuable chemicals. A promising platform for next‐generation biomanufacturing, the semiconductor‐cyanobacterial hybrid systems are capable of enhancing the solar‐to‐chemical conversion efficiency. Herein, the native ethylene‐producing capability of a filamentous cyanobacterium Nostoc sphaeroides is confirmed experimentally. The self‐assembly characteristic of N. sphaeroides is exploited to facilitate its interaction with InP nanomaterial, and the resulting biohybrid system gave rise to further elevated photosynthetic ethylene production. Based on chlorophyll fluorescence measurement and metabolic analysis, the InP nanomaterial‐augmented photosystem I activity and enhanced ethylene production metabolism of biohybrid cells are confirmed, the mechanism underlying the material‐cell energy transduction as well as nanomaterial‐modulated photosynthetic light and dark reactions are established. This work not only demonstrates the potential application of semiconductor‐N. sphaeroides biohybrid system as a good platform for sustainable ethylene production but also provides an important reference for future studies to construct and optimize nano‐cell biohybrid systems for efficient solar‐driven valuable chemical production. [ABSTRACT FROM AUTHOR]

ZnMgO nanoparticles (NPs) are commonly used as the electron transport layer (ETL) in indium phosphide (InP) based quantum dots light‐emitting diodes (QLEDs). It has been experimentally found that the inherent oxygen vacancy defects in ZnMgO can be passivated by halogen additives. However, an in‐depth understanding of how the halogen additives in ZnMgO affect the quantum dots (QDs) films is currently missing. Here, the study reports on efficient and stable indium phosphide (InP) green QLEDs by effectively bridging QDs and ETL using chloride (Cl) ions. As bi‐functional anchoring additives, Cl ions not only passivate the oxygen vacancy defects of ZnMgO NPs for suppressing the exciton quenching at the QDs/ZnMgO interfaces, but also facilitate the hole transport of QDs due to part replacement of insulated oleic acid ligands on the surfaces of InP QDs with Cl anions for more balanced charge injection in the devices. Consequently, the optimized green InP QLED achieves a peak external quantum efficiency (EQE) of 13.8% and an operational lifetime of 5944 h, which, to the best of current knowledge, represents the best overall performance among the reported green InP QLEDs. [ABSTRACT FROM AUTHOR]

Recently, single‐crystalline indium phosphide (InP) tetrapods, which allow an exciton to act in a true tetrapodal geometry, were successfully synthesized and proved as a useful platform to study multiple exciton behaviors. We used ZnCl2 precursor, a commonly used additive in the synthesis of aminophosphine‐based InP nanocrystals to enhance the optical performance, and successfully synthesized InP tetrapods (InP‐ZnCl2) with the narrower arm length distribution. Interestingly, no distinct enhancement in photoluminescence was observed while the arm length of the InP tetrapod was suppressed with the addition of ZnCl2. Further shell growth on InP‐ZnCl2 successfully preserved tetrapodal geometry in InP‐ZnCl2/ZnSe and showed higher photoluminescence than that of tetrapodal InP/ZnSe. The crystal structure of InP‐ZnCl2 was also retained even along with various Zn feed ratios as observed in x‐ray diffraction (XRD) patterns and showed no peak shift as Zn only passivates the surface of InP tetrapods. These results provide a platform to study the role of Zn precursor. [ABSTRACT FROM AUTHOR]

Recently, single‐crystalline indium phosphide (InP) tetrapods, which allow an exciton to act in a true tetrapodal geometry, were successfully synthesized and proved as a useful platform to study multiple exciton behaviors. We used ZnCl2 precursor, a commonly used additive in the synthesis of aminophosphine‐based InP nanocrystals to enhance the optical performance, and successfully synthesized InP tetrapods (InP‐ZnCl2) with the narrower arm length distribution. Interestingly, no distinct enhancement in photoluminescence was observed while the arm length of the InP tetrapod was suppressed with the addition of ZnCl2. Further shell growth on InP‐ZnCl2 successfully preserved tetrapodal geometry in InP‐ZnCl2/ZnSe and showed higher photoluminescence than that of tetrapodal InP/ZnSe. The crystal structure of InP‐ZnCl2 was also retained even along with various Zn feed ratios as observed in x‐ray diffraction (XRD) patterns and showed no peak shift as Zn only passivates the surface of InP tetrapods. These results provide a platform to study the role of Zn precursor. [ABSTRACT FROM AUTHOR]

Balanced charge injection into the emissive layer is a prerequisite for achieving highly efficient quantum dot light‐emitting diodes (QLEDs). The similar energy distribution of charge transport layers and indium phosphide (InP) quantum dots (QDs) facilitates excess electron injection to the InP QD layer. In this study, magnesium‐doped ZnO nanoparticles (ZMO NPs) are modified to suppress the electron injection to the InP QD layer. Particularly, hydroxyl groups are effectively replaced by electrically stable states through the passivation of ZMO NPs, retarding electron injection through the ZMO NP layer. The modified ZMO‐NP‐based InP QLEDs exhibit a maximum external quantum efficiency of 9.6% with a substantially enhanced operational lifetime compared with that of devices made with unmodified ZMO NPs. [ABSTRACT FROM AUTHOR]

Colloidal indium phosphide quantum dots (In(Zn)P/ZnS QDs) show potential for application in the field of light emitting diodes (LED) and Mini/Micro‐LEDs displays due to their tunable emission and low toxicity. However, the performance of blue‐emitting indium phosphide QDs is still lagging behind that of red and green. Herein, a facile method to overcome this difficulty is proposed. The highly active Zn(ClO4)2 precursor is injected into the reaction mixture during the nucleation process to enhance zinc incorporation, which generates the In(Zn)P alloy QDs with enlarged bandgap. At the same time, the increase of zinc content can inhibit excessive growth of In(Zn)P QDs, and significantly improve its size distribution. The monodisperse In(Zn)P/ZnS QDs exhibit excellent blue emission (466 nm) and have the narrowest full width at half maxima (41 nm) of blue emission In(Zn)P QDs ever reported. This work provides a feasible and effective strategy for obtaining narrow‐band blue‐emitting In(Zn)P/ZnS QDs. [ABSTRACT FROM AUTHOR]

III–V semiconductors are among the highest performing materials for solar energy conversion devices. Exposing III–V semiconductors to a hydrogen plasma can improve optoelectronic properties and is a critical step in fabricating efficient InP solar cells. However, there is a limited understanding of the changes induced by hydrogen plasma exposure to the surface and in the bulk of III–V semiconductors. Herein, it is demonstrated that a 19.3% efficient p‐InP solar cell with a TiO2 electron selective contact layer can be achieved by exposing the InP substrate to hydrogen plasma. Detailed investigations employing ultraviolet photoelectron spectroscopy and capacitance–voltage measurement unveil that the hydrogen plasma exposure on p‐InP leads to charge carrier polarity inversion in the near‐surface region (charge inversion layer) while simultaneously reducing the carrier concentration (charge‐depleted layer) in the bulk. The study provides important insights into the impact of hydrogen plasma exposures on InP which may lead to more efficient optoelectronic devices such as solar cells, photodetectors, light‐emitting diodes, and photoelectrochemical cells. [ABSTRACT FROM AUTHOR]

We report phosphinidenes (PR) stabilized by an intramolecular frustrated Lewis pair (FLP) chelate. These adducts include the parent phosphinidene, PH, which is accessed via thermolysis of coordinated HPCO. The reported FLP‐PH species acts as a springboard to other phosphorus‐containing compounds, such as FLP‐adducts of diphosphorus (P2) and InP3. Our new adducts participate in thermal‐ or light‐induced phosphinidene elimination (of both PH and PR, R=organic group), transfer P2 units to an organic substrate, and yield the useful semiconductor InP at only 110 °C from solution. [ABSTRACT FROM AUTHOR]

Quantum dot light‐emitting diodes (QLEDs), regarded as promising candidates in the next‐generation display, have attracted much attention recently. In spite of the outstanding performance of cadmium‐based (Cd‐based) QLEDs, the toxicity of Cd hinders their wide application. Indium phosphide quantum dots (InP QDs) with heavy‐metal‐free feature and competitive performance are considered to be able to replace Cd‐based QDs as emitting layer in the QLEDs. Much progress is obtained in the red‐emitting and green‐emitting InP‐based QLEDs. However, the blue‐emitting ones are faced with great challenges and are demanded on full‐color display urgently, which is limited by the inferior performance of blue‐emitting InP QDs and lack of investigations about their QLED devices. In this review, the encountered challenges for high‐quality blue‐emitting InP QDs are presented. Common strategies for blue‐emitting InP QDs, including size engineering, composition engineering, and surface engineering are presented and analyzed. The progress of blue‐emitting InP‐based QLEDs, which strongly relies on the advances of materials, is also summarized. Finally, some perspectives from device physics are provided and discussed to inspire more efficient strategies toward blue‐emitting InP‐based QLEDs. [ABSTRACT FROM AUTHOR]

Development and scalable nanomanufacturing of high‐quality heavy metal‐free quantum dots (QDs) with high‐dimensional experimental design spaces still remain a challenge. In this work, a universal flow chemistry framework for accelerated fundamental and applied studies of heavy metal‐free QDs with multi‐stage chemistries is presented. By introducing flexible time‐ and temperature‐to‐distance transformation using modular fluidic blocks, an in‐flow synthetic route of InP QDs with the highest reported first excitonic absorption peak to valley ratio is unveiled with a reaction time one order of magnitude faster than batch reactors. The flexible time‐ and temperature‐to‐distance transformation as an enabling factor for generalization of flow reactors toward the accelerated discovery, development, and nanomanufacturing of high‐quality emerging nanomaterials for next‐generation energy, display, and chemical technologies is discussed. [ABSTRACT FROM AUTHOR]

Microwave photonics (MWP) is an emerging field that studies the interaction between microwave and lightwave for myriad communication and information applications. Recently, new opportunity for MWP has emerged driven by the advances of integrated photonics. However, despite significant progress made in terms of integration level, a fully on‐chip MWP functional system comprising all the necessary photonic and electronic components, is yet to be demonstrated. Here, the status quo is broken and a complete on‐chip solution for MWP system is provided, by exploiting hybrid integration of indium phosphide, silicon photonics, and complementary metal‐oxide–semiconductor electronics platforms. Applying this hybrid integration methodology, a fully chip‐based MWP instantaneous frequency measurement (IFM) system is demonstrated. The unprecedented integration level brings great promotion to the compactness, reliability and performances of the MWP IFM system, including a wide frequency measurement range (2–34 GHz), ultralow estimation errors (10.85 MHz), and a fast response speed (≈0.3 ns). Furthermore, the chip‐scale MWP IFM system is deployed into realistic tasks, where diverse microwave signals with rapid‐varying frequencies at X‐band (8–12 GHz) are accurately identified in real‐time. This demonstration marks a milestone for the integrated MWP, by providing the technology basis for the miniaturization and massive implementations of various MWP systems. [ABSTRACT FROM AUTHOR]

Indium phosphide (InP) based quantum dots (QDs) have been known as an ideal alternative to heavy metals including QDs light emitters, such as cadmium selenium (CdSe) QDs, and show great promise in the next‐generation solid‐state lighting and displays. However, the electroluminescence performance of green InP QDs is still inferior to their red counterparts, due to the higher density of surface defects and the wider particle size distribution. Here, a quasi‐shell‐growth strategy for the growth of highly luminescent green InP/ZnSe/ZnS QDs is reported, in which the zinc and selenium monomers are added at the initial nucleation of InP stage to adsorb on the surface of InP cores that create a quasi‐ZnSe shell rather than a bulk ZnSe shell. The quasi‐ZnSe shell reduces the surface defects of InP core by passivating In‐terminated vacancies, and suppresses the Ostwald ripening of InP core at high temperatures, leading to a photoluminescence quantum yield of 91% with a narrow emission linewidth of 36 nm for the synthesized InP/ZnSe/ZnS QDs. Consequently, the light‐emitting diodes based on the green QDs realize a maximum luminance of 15606 cd m−2, a peak external quantum efficiency of 10.6%, and a long half lifetime of > 5000 h. [ABSTRACT FROM AUTHOR]

Single‐crystal indium phosphide (InP) was irradiated by swift heavy ions (40Ar, 56Fe, 86Kr, 181Ta, and 209Bi) with different energies. The damage evolutions have been investigated by means of Raman spectroscopy and electron microscopy. Analysis of Raman intensity ratio (LO′ peak to LO peak [ILO′/ILO]) provides a new insight into the lattice quality of the irradiated samples. The defect‐activated longitudinal optical mode (LO′) appeared and then disappeared with increasing ion fluences, and it seems that the peak point of ILO′/ILO is electronic energy loss dependent. The phenomenological model suggests that the LO′ peak intensity is positively correlated with the proportion of the activated regions, where the crystals were not completely disordered, but still many defects were created. Furthermore, the TEM images showed that the tracks closely overlapped, resulting in the decrease of activated regions, which implies that there is a competitive mechanism between the generation and annealing of the defects. It also provides direct evidence that the annealing effect of the defects has occurred during the swift heavy‐ion irradiation. [ABSTRACT FROM AUTHOR]

Blue indium phosphide quantum dot (InP QD) is an emerging colloidal semiconductor nanocrystal, considered as a promising next‐generation photoactive material for light‐emitting purposes. Despite the tremendous progress in blue InP QDs, the synthetic method for tailoring InP core size to realize the blue‐emissive QDs still lags behind. This work suggests a synthetic method for blue‐emitting InP QDs by engineering the core size with an incipient ZnS (i‐ZnS) shell. The formation of i‐ZnS complexes, before the tris(trimethylsilyl)phosphine injection (e.g., before core growth process), restrains the overgrowth of InP nuclei by rapidly forming a ZnS shell on its surface, thereby resulting in further dwarfed InP cores. With additional ZnS shell coating, the blue QDs exhibit a photoluminescence quantum yield of ≈52% at 483 nm. The origin of bandgap diminution with the increase of shell thickness, or with the utilization of ZnSe shell is unraveled via the first‐principles density functional theory simulations. Simulational evidence on InP‐core densification with the shell coating, along with accompanying changes in chemical and structural properties, is presented. The blue‐emitting InP QD device shows a maximum luminance of 1162 cd m−2 and external quantum efficiency of 1.4%. [ABSTRACT FROM AUTHOR]

Indium phosphide (InP) quantum dots (QDs) are in an unrivaled position in photoluminescence (PL) performances particularly for green and red color over other heavy‐metal‐free QD visible emitters. Herein, based on InP cores synthesized using an easy‐to‐handle, safe aminophosphine precursor, unprecedented bright, narrow emissivity is demonstrated synergically by optimizing double shelling scheme and Ga treatment. Two comparative double shells of ZnSe0.5S0.5/ZnS versus ZnSe/ZnS are generated on green‐emissive InP cores, yielding better PL outcomes with respect to PL quantum yield (QY) and full‐width‐at‐half‐maximum (FWHM) from the latter scheme over the former one. With an intent to further enhance emissivity, incorporation of Ga onto InP cores in the course of ZnSe inner shelling is newly devised. Properly Ga‐treated InP/ZnSe/ZnS QDs, where Ga is presumed to play a beneficial role in removing surface P dangling bond of InP core, produce a near‐unity PLQY (97%) and narrow FWHM of 37 nm. The similar effectiveness is also verified in red InP/ZnSe/ZnS heterostructure, clearly indicating that Ga treatment is a viable, valid strategy toward bright emissivity in the InP QD system. [ABSTRACT FROM AUTHOR]

One of the major challenges for novel display technologies based on quantum dot light‐emitting (QLED) was replacing toxic emission layers. Indium phosphide (InP) quantum dots were considered as the most promising alternative materials. In this work, the optimal vertical light extraction could be obtained by simulating the different thickness of electron transport layer (ETL) in devices. The Mg‐doped ZnO (ZnMgO) electron transport layer was adopted to further balance the carriers injection and transport. Finally, top‐emission devices with optimized light extraction and balanced carriers shown higher current efficiency and narrower full width at half maximum (FWHM) of electroluminescent peaks (EL). [ABSTRACT FROM AUTHOR]

Room‐temperature continuous wave (RT‐CW) electrically pumped 1550 nm indium phosphide (InP)‐based laser diodes are realized on complementary metal‐oxide‐semiconductor (CMOS) compatible silicon (Si) substrates by direct heteroepitaxy. Dynamic properties are investigated by gain switching and small signal modulation measurements. A maximum 3 dB bandwidth of 5.3 GHz is demonstrated, along with a narrow optical pulse with a width of 1.5 ns. The dark current density of 490 mA cm−2 at −1 V bias is an order of magnitude higher than identical devices grown and fabricated on native InP substrates. Also, reliability measurements and failure analysis are carried out for the lasers on Si. The lasers operate stably over 200 hours (h) at 10 °C under CW operation without apparent change in threshold or output power. In sharp contrast, a rapid failure occurs at 60 °C under pulsed operation following 5.6 h of aging. To further improve device characteristics for lasers on Si, the dislocation density of the InP template is reduced by introducing a 2 μm‐thick compositionally graded In0.4Ga0.6 As buffer. The resulting surface defect density is as low as 4.5 × 107 cm−2, which is expected to improve the performance and reliability of long wavelength lasers grown directly on Si. [ABSTRACT FROM AUTHOR]

Indium phosphide (InP)‐based high electron mobility transistors (HEMTs) with an offset gate enable higher maximum oscillation frequency (fMAX) values because of the resulting reduction in gate‐to‐source resistance. Following this approach, improved direct current (DC) characteristics and cutoff frequencies (fT/fMAX > 410/710 GHz with LG = 50 nm) are shown with respect to centered gate devices. However, HEMTs with an offset gate show degraded noise performances compared with centered gate devices because of a higher gate leakage current. The results show that offsetting the gate closer to the source is not desirable for ultra‐low‐noise performance. [ABSTRACT FROM AUTHOR]

A lossless solar cell operating at the Shockley–Queisser limit generates an open circuit voltage (Voc) equal to the radiative limit. At Voc, the highly directional beam of photons from the sun is absorbed and subsequently externally re‐emitted into a 4π solid angle, providing a large photon entropy loss. A solar cell can beat the Shockley–Queisser limit and approach the 46.7% ultimate limit by decreasing the output solid angle of the light emission at open circuit conditions. Here, a design for an indium phosphide single nanowire solar cell capable to operate 159 mV above the radiative limit is presented. The spontaneous emission factor is first optimized into a guided mode of the nanowire toward 68%. The authors subsequently launch a guided mode at the bottom straight part of the tapered nanowire yielding a photon escape probability of 81% for a tapering angle of θ = 1.2° and a top facet with a radius of 83 nm. When assuming homogeneous light emission along the nanowire, an outcoupling efficiency of 42% of the emitted light is obtained. The final optimization is the reduction of the emission cone toward 11 × 10−3 sr by focusing the guided mode with an external lens. [ABSTRACT FROM AUTHOR]

Black titanium dioxide (TiO2) quantum dots (QDs) are grown by a solution‐based electrochemical process and an effect of KCl concentration on the growth is investigated. The electrochemical process is demonstrated as a simple one‐step process for the growth of black TiO2 QDs in the solutions via bottom–up process. From the absorption spectra, the absorption appears for an entire visible wavelength (400–700 nm) implying a black TiO2 property. The average size of the black TiO2 QDs is about 4.5 nm from the transmission electron microscopy results and is similar to all KCl concentrations. This indicates that KCl concentration has no effect on the particle size, but has effect on the hydrodynamic size of TiO2 QDs. The black TiO2 QDs can be produced by the hydrogenation process of hydrogen ions during electrochemical process. The obtained black TiO2 QDs can be further explored as an electron‐transporting layer for a perovskite solar cell application. [ABSTRACT FROM AUTHOR]

Photocatalytic conversion of CO2 into storable fuels is an attractive way to simultaneously address worldwide energy demands and environmental problems. Semiconductor quantum dots (QDs) have gained prominence as candidates for photocatalytic applications due to their many advantages, which include tunability for advanced electronic, optical, and surface properties. Indium phosphide (InP) quantum dots are semiconducting QDs with enormous potential for solar‐driven CO2 reduction. Their advantages include a tunable bandgap, diverse surface chemistry, and nontoxicity. InP QDs and CdS nanorods were integrated using a simple and inexpensive method. CO2 photoreduction by the CdS‐InP composites was evaluated in aqueous solution using triethanolamine as a sacrificial donor. The crystal structures, surface compositions, and morphologies were investigated via X‐ray diffraction analysis, X‐ray photoelectron spectroscopy, and transmission electron microscopy, respectively. The UV‐visible diffuse reflectance spectra of the CdS‐InP composites indicated efficient visible light utilization in the 500–550 nm range. The results of photoelectrochemical and photoluminescence analyses illustrated effective charge separation in the composites. The photocatalytic activity of the as‐synthesized composites was superior to that of pure CdS. The CO evolution rate of the optimized composite was 216 μmol h−1 g−1 during the first three hours of irradiation and increased steadily over the next 62 hours. We also studied the influences of different solvents, the hole scavenger concentration, and catalyst loading on the performance of the optimized composite. [ABSTRACT FROM AUTHOR]

Although semiconductor nanowire (NW) photodetectors are promising building blocks for nanoscale on‐chip optoelectronic integration applications, poor absorption, and strong light polarization dependence due to their inherent anisotropic geometry remain an issue. Here, a polarization‐insensitive photodetector is designed and experimentally demonstrated, which consists of an InP NW embedded in a dual‐split bull's eye (DSBE) plasmonic antenna. The resultant photodetector exhibits a low noise equivalent power of 0.97 pW and a photoresponsivity of 0.96 A W‐1 at 740 nm with an external quantum efficiency of 163%. Importantly, the device exhibits an ultralow polarization dependence characteristic with a polarization degree significantly reduced from 91% down to 6%. The improved performance stems from the intrinsic symmetry of the orthogonal DSBE and the strong surface plasmon coupling, which significantly boosts the optical concentration abilities at all polarization angles as compared to the bare NW photodetector. This NW photodetector‐antenna design provides a pathway for the development of high‐performance nanoscale photodetectors for applications in advanced sensing, imaging, and quantum communications. [ABSTRACT FROM AUTHOR]

InP‐based quantum dot (QD) has been emerged as an environment‐friendly emitter for wide color gamut (WCG) display. In this work, we optimized the composition and structure of multishell on the InP core. As a result, photoluminescence quantum yield (PL QY, 95%) and the full width at halfmaximum (FWHM, 36 nm), with perfectly matched wavelength (528 nm) for the green color in WCG displays. [ABSTRACT FROM AUTHOR]

A novel modeling methodology for indium phosphide (InP) double heterojunction bipolar transistors (DHBTs) based on the theory of Bayesian inference, a well‐known method from the field of machine learning, is presented in this article. An extremely broadband small‐signal behavioral model, from 200 MHz to 325 GHz, is built, tested, and validated in this work, with excellent agreement obtained between the extracted model and the experimental data in the form of S‐parameters. A single finger InP DHBT device, with emitter size of 0.5 × 5 μm2 exhibiting an ft of over 550 GHz, is used in the verification example. Taking advantage of regression techniques based on machine learning concepts, the proposed black‐box behavioral model can more accurately predict the behavior of the device compared with the traditional equivalent circuit modeling method. Several sets of measured vs modeled data are shown, indicating the efficacy of the method. [ABSTRACT FROM AUTHOR]

Indium phosphide (InP)‐based transistors play an important role in high‐speed circuit and high‐frequency analog circuit applications. Over the past few decades, terahertz heterojunction bipolar transistor (HBT) is increasingly developed. As a result, many reports of HBTs operating at terahertz region have flourished. Since the high‐frequency circuit design faces the challenge from the lack of precise transistor models, this paper reviews the development of high‐frequency modeling technologies of InP HBT at terahertz region. Processes in the development of small‐signal models at terahertz frequencies, precise parasitic parameters extraction method, improvements in measurement, and the de‐embedding technologies open up more opportunities for precise representation of InP HBTs. Finally, some excellent terahertz circuits based on InP HBT are reviewed. [ABSTRACT FROM AUTHOR]

This paper reports a power amplifier (PA) terahertz monolithic integrated circuit (TMIC) from 180 to 240 GHz. This amplifier is fabricated from a 0.5‐μm indium phosphide double heterojunction bipolar transistor (InP DHBT) technology, jointly with a thin‐film microstrip wiring environment. Furthermore, an electromagnetic (EM) simulation method is proposed for the parameter extraction of InP DHBTs and amplifier design. This five‐stage amplifier has >6.1 dB S21 gain from 180 to 240 GHz, peaks 10.4 dB S21 gain at 210 GHz. At 213 GHz operation, the saturated output power is 5.8 dBm with 7.3 dB large‐signal gain, and this amplifier occupies 2.52 mm2 including pads. [ABSTRACT FROM AUTHOR]

Analytical expressions for the short‐circuit current gain and unilateral power gain of common emitter heterojunction bipolar transistor (HBT) are presented in this paper. These expressions are derived from a simplified π‐type small signal equivalent circuit model, which takes into account the influence of the extrinsic resistances and base‐collector capacitance distributed nature. Good agreement is obtained between measured and calculated results for both two indium phosphide (InP) HBT devices and a gallium arsenide (GaAs) HBT device over a wide range of bias points. [ABSTRACT FROM AUTHOR]

Raman spectroscopy can provide a detailed analysis of mechanical stress in crystalline materials through the measurement of shifts in vibrational frequency. However, the ambient temperature drift during measurements can lead to inaccurate mechanical stress values. Herein, the 2D Raman mapping analysis of gallium nitride (GaN) and aluminum indium gallium phosphide (AlInGaP) epitaxial films within packaged light‐emitting diode (LED) devices reveals micrometer‐scale localized stress distributions. A temperature‐corrected measurement method is developed to evaluate the mechanical stress of InGaN LED dies at various LED operating conditions. The impact of die design on mechanical stress is studied for both GaN on Al2O3 (chip scale package, CSP) and GaN thin‐film flip chip (TFFC) designs. Raman mapping of AlInGaP LEDs is also demonstrated and shows comparable resolution with the GaN LED results. [ABSTRACT FROM AUTHOR]

Indium phosphide (InP) quantum dots (QDs) are ideal substitutes for widely used cadmium‐based QDs and have great application prospects in biological fields due to their environmentally benign properties and human safety. However, the synthesis of InP core/shell QDs with biocompatibility, high quantum yield (QY), uniform particle size, and high stability is still a challenging subject. Herein, high quality (QY up to 72%) thick shell InP/GaP/ZnS core/shell QDs (12.8 ± 1.4 nm) are synthesized using multiple injections of shell precursor and extension of shell growth time, with GaP serving as the intermediate layer and 1‐octanethiol acting as the new S source. The thick shell InP/GaP/ZnS core/shell QDs still keep high QY and photostability after transfer into water. InP/GaP/ZnS core/shell QDs as fluorescence labels to establish QD‐based fluorescence‐linked immunosorbent assay (QD‐FLISA) for quantitative detection of C‐reactive protein (CRP), and a calibration curve is established between fluorescence intensity and CRP concentrations (range: 1–800 ng mL−1, correlation coefficient: R2 = 0.9992). The limit of detection is 2.9 ng mL−1, which increases twofold compared to previously reported cadmium‐free QD‐based immunoassays. Thus, InP/GaP/ZnS core/shell QDs as a great promise fluorescence labeling material, provide a new route for cadmium‐free sensitive and specific immunoassays in biomedical fields. [ABSTRACT FROM AUTHOR]

This study reports on a sub‐mW triple‐push oscillator using resonant tunnelling diodes (RTDs) operating at a frequency of 225 GHz. The triple‐push RTD oscillator is designed based on a stability test using even/odd‐mode equivalent circuit models and fabricated by using an indium phosphide monolithic microwave integrated circuit process. The fabricated IC exhibits an extremely low dc‐power consumption (PDC) of 0.5 mW with a dc‐to‐radio‐frequency efficiency of 1%. These results are attributed to both device characteristics of the RTDs with a low bias voltage of 0.4 V and a low peak current density of 0.74 mA/μm2 and an efficient triple‐push topology exploiting the strong odd symmetry of the RTD I–V curve with a wide negative differential conductance voltage span of 0.46 V. [ABSTRACT FROM AUTHOR]

The emergence of multidrug‐resistant (MDR) pathogens represents one of the most urgent global public health crises. Light‐activated quantum dots (QDs) are alternative antimicrobials, with efficient transport, low cost, and therapeutic efficacy, and they can act as antibiotic potentiators, with a mechanism of action orthogonal to small‐molecule drugs. Furthermore, light‐activation enhances control over the spatiotemporal release and dose of the therapeutic superoxide radicals from QDs. However, the limited deep‐tissue penetration of visible light needed for QD activation, and concern over trace heavy metals, have prevented further translation. Herein, we report two indium phosphide (InP) QDs that operate in the near‐infrared and deep‐red light window, enabling deeper tissue penetration. These heavy‐metal‐free QDs eliminate MDR pathogenic bacteria, while remaining non‐toxic to host human cells. This work provides a pathway for advancing QD nanotherapeutics to combat MDR superbugs. [ABSTRACT FROM AUTHOR]

The authors propose a 2 × 2 asymmetric adiabatic coupler (AAC) indium phosphide (InP) photonic integrated circuit (PIC), suitable for tunable power applications such as all-optical data processing. The device was idealised as the key building block in Haar transform network used for image compression, allowing to perform the necessary separate addition and subtraction of incoming input signals at its output ports. The tunable behaviour of the coupler was demonstrated experimentally for addition/subtraction and splitting (with experimental coupling ratios of 77:23/14:86 and 50:50, respectively) through phase control. The use of the developed InP PIC enables a low footprint structure design together with the high-quality active components (lasers, photodetectors and phase modulators) of Fraunhofer Gesellschaft Heinrich Hertz Institute design toolkit. The proposed study provides a full experimental characterisation of the AAC, exploring its tuning properties and enabling further usage in a plethora of applications in high processing computing and data communications. [ABSTRACT FROM AUTHOR]

A monolithic microwave‐integrated circuit 2‐stage power amplifier (PA) realized in indium phosphide double heterojunction bipolar transistor technology is presented in this article. The 2‐ and 3‐stacked transistors are used in the driver and power stages, respectively. As a mean to increase the output power capabilities, 2‐ and 4‐way corporate power combiners are implemented in coplanar waveguide technology. The fabricated PA exhibits a small‐signal gain of 13.6 dB at 77 GHz and a 3‐dB bandwidth ranging from 74 to 86 GHz. At 78 GHz, the saturated output power is >19.6 dBm. [ABSTRACT FROM AUTHOR]

This Letter reports the design, fabrication and characterisation of a new differential linear driver, fabricated in the III-V Lab 0.7- ${\rm \mu }{\rm m}$μm emitter width indium phosphide (InP) double heterojunction bipolar transistor (DHBT) technology. Large-signal electrical characterisation shows 80-GBd symbol-rate four-level pulse amplitude (PAM-4) modulation conjugated with a driver output swing of 3-Vppdiff and a 0.74-W power consumption. Thus resulting in a 1.22-GBd driving efficiency, the highest in over 70-GBd drivers' state-of-the-art, at that date. Accordingly, S-parameter measurements of the standalone linear driver exhibit the highest gain-bandwidth product of 556 GHz, in that current state-of-the-art. [ABSTRACT FROM AUTHOR]

Gas cluster ion beam is performed on an ultrathin "polyphosphazene‐like" film grown on indium phosphide substrates to obtain crucial properties of this model system. Unlike "standard" sputtering technique using monoatomic ions, a gentle progressive digging of this subnanometric thick layer has been realized thanks to the unique depth profiling features of gas cluster ion beam. Furthermore, our results highlight the properties of the electrochemically formed film made of phosphorus‐nitrogen electron‐rich chemical bond creating a strong attenuation of the photoelectron underneath. Such approach opens exciting insights in the chemical and physical analysis of sensitive surfaces as ultrathin covering layers. [ABSTRACT FROM AUTHOR]

Abstract: P‐substrate AlGaInAs/InP lasers are enabled using an internal carbon‐doped layer to block Zn‐diffusion. These inverted lasers are developed for the aim of further monolithic vertical integration with passive or active material, which would allow full system on‐chip integration. The lasers emit at 1.5 μm making them ideal for telecommunication applications. Different p‐substrate laser designs were grown to quantify the effect the carbon doped layer had on blocking Zn p‐dopants diffusion, which permits the long growths necessary for vertical integration. Current, voltage, and capacitance measurements were used to examine the different laser designs, proving that Zn p‐dopant diffusion is responsible for p‐substrate laser failure. [ABSTRACT FROM AUTHOR]

Surface gratings are widely used in photonic integrated circuits (PICs). In this paper, the authors study the fabrication of surface gratings on indium phosphide (InP) based materials by inductively coupled plasma (ICP) dry etching. The etching parameters are optimized to achieve high aspect ratio while maintaining excellent surface morphology. A novel processing technique is presented for surface grating formation on top of a deeply etched ridge waveguide by taking advantages of the lag effect. Fine structures with non‐uniform height can be completed in a single‐step ICP dry etching, thus greatly simplifying the fabrication by eliminating the demanding overlay process. The method is believe to be valuable for the fabrication of a variety of PICs containing hyperfine structures. [ABSTRACT FROM AUTHOR]

Abstract: Despite the growing interest in quantum dots for applications ranging from bioimaging to display technologies, the reproducible and high‐quality synthesis of Cd‐free quantum dots (QDs) on a large scale remains challenging. Conventional large‐scale batch synthesis techniques are limited by slow precursor heating/cooling/mixing, poor reproducibility and low productivity. In recent years, the continuous flow synthesis of QDs using microfluidic approaches has shown promise to overcome the shortcomings of batch synthesis. However, the application of microfluidic reactors for synthesis of Cd‐free QDs exhibiting high photoluminescence quantum yield (PL QY) at high production rate remains a challenge. Here, we report a modular millifluidic reactor for the fully continuous multi‐step synthesis of InP/ZnSeS core‐shell QDs, that integrates the precise control over reaction conditions with the potential for gram‐scale production rates. We use a design of experiment approach to understand and optimize the process parameters for the synthesis, resulting in PL QY up to 67% with good reproducibility in terms of both QY and peak position (less than 5% standard deviation). Additionally, by changing the process parameters for different reaction stages (core and shell reactors), the wavelength of the InP/ZnSeS particles can be tuned to cover nearly the entire visible spectrum (480–650 nm). [ABSTRACT FROM AUTHOR]