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Abstract In this paper, a 280–300 GHz hybrid‐integrated transmitter is proposed. The advantages of the SiGe and InP chips are fully made use by integrating these two chips. For low cost and high integration, the local oscillator chain and mixer are based on chips in SiGe technology, and the 300‐GHz power amplifier and on‐chip antenna are realised in InP technology for high output power and small die size. The low‐cost bonding wires are introduced for the interconnection between these two chips, and the lens are attached above the on‐chip antenna for further EIRP enhancement. Finally, the proposed transmitter is fabricated and measured, which shows comparable performances with 21.9 dBm EIRP (equivalent isotropic radiated power) and 10 Gbps data rate.

Abstract The authors present continuous wave (CW) high‐power broad area and ridge waveguide lasers with laser emission at 626 nm at room temperature. For this, the authors employ GaAs‐based diode lasers in the AlGaInP system for laser emission at 626 nm at room temperature. The laser structure is grown on three‐inch wafers by metal organic vapour phase epitaxy. Broad area and ridge waveguide lasers are fabricated. Pulsed broad area laser characterisation on bar level shows laser operation at 20 C heat sink temperature. The authors measured peak lasing wavelengths as short as 625 nm and total maximum output power of both facets up to 1.4 W at an injection current of 2 A. Both, broad area and ridge waveguide lasers show laser operation and CW excitation at room temperature. The ridge waveguide lasers emit output powers of over 90 mW at 626 nm at a maximum injection current of 200 mA with a nearly diffraction‐limited beam profile.

In this paper, a 280–300 GHz hybrid‐integrated transmitter is proposed. The advantages of the SiGe and InP chips are fully made use by integrating these two chips. For low cost and high integration, the local oscillator chain and mixer are based on chips in SiGe technology, and the 300‐GHz power amplifier and on‐chip antenna are realised in InP technology for high output power and small die size. The low‐cost bonding wires are introduced for the interconnection between these two chips, and the lens are attached above the on‐chip antenna for further EIRP enhancement. Finally, the proposed transmitter is fabricated and measured, which shows comparable performances with 21.9 dBm EIRP (equivalent isotropic radiated power) and 10 Gbps data rate. [ABSTRACT FROM AUTHOR]

Gallium nitride (GaN)‐based semiconductor laser diodes (LDs) have garnered significant attention due to their promising applications. However, high‐power LDs face serious degradation issues that limit their practical use. This study investigates the degradation factors of 437 nm and 6.3 W LDs by comparing light–current–voltage (L–I–V) characteristics, transmission electron microscopy (TEM), cathodoluminescence (CL), and secondary ion mass spectroscopy (SIMS) before and after 1000‐h aging. The diffusion of mirror coating from the resonant cavity surface is identified as a key factor contributing to high‐power LD degradation, which has not been reported in milliwatt‐level LDs. Meanwhile, the mechanisms behind the LD degradation are profiled and summarized together with the diffusion and other factors. On basis of the mechanism exploration, an anti‐aging technology for high‐power GaN‐based LDs is developed by using aluminum nitride for passivation layer and sapphire materials for mirror film. This anti‐aging technology has been verified, and a nearly ten‐time degradation suppression is achieved from 1000 h. This study elucidates the degradation mechanisms of high‐power GaN LDs and provides an effective technology to extend their lifespan, thereby prompting the practical applications of high‐power LDs. [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]

The authors present continuous wave (CW) high‐power broad area and ridge waveguide lasers with laser emission at 626 nm at room temperature. For this, the authors employ GaAs‐based diode lasers in the AlGaInP system for laser emission at 626 nm at room temperature. The laser structure is grown on three‐inch wafers by metal organic vapour phase epitaxy. Broad area and ridge waveguide lasers are fabricated. Pulsed broad area laser characterisation on bar level shows laser operation at 20 C heat sink temperature. The authors measured peak lasing wavelengths as short as 625 nm and total maximum output power of both facets up to 1.4 W at an injection current of 2 A. Both, broad area and ridge waveguide lasers show laser operation and CW excitation at room temperature. The ridge waveguide lasers emit output powers of over 90 mW at 626 nm at a maximum injection current of 200 mA with a nearly diffraction‐limited beam profile. [ABSTRACT FROM AUTHOR]

Abstract This review aims to provide a comprehensive overview of the development and current understanding of GaAs and InAs heterostructures, with a special emphasis on achieving high material quality and high-mobility two-dimensional electron gases (2DEGs). The review discusses the evolution of structural designs that have significantly contributed to the enhancement of electron mobility, highlighting the critical considerations of scattering mechanisms of the 2DEGs. In addition, this review examines the substantial contributions of Molecular Beam Epitaxy (MBE) to these developments, particularly through advancements in vacuum technology, source material purification, and precision control of growth conditions. The intent of this review is to serve as a useful reference for researchers and practitioners in the field, offering insights into the historical progression and technical details of these semiconductor systems.

Highlights In-depth review assesses III–V materials for efficient hydrogen generation and CO2 reduction in renewable energy technologies. Exploration of strategies for broad light absorption and increased efficiency in water splitting processes and CO2 reduction. Innovative electrode designs conclude the path for stable, large-scale implementation of clean energy systems.

This review aims to provide a comprehensive overview of the development and current understanding of GaAs and InAs heterostructures, with a special emphasis on achieving high material quality and high-mobility two-dimensional electron gases (2DEGs). The review discusses the evolution of structural designs that have significantly contributed to the enhancement of electron mobility, highlighting the critical considerations of scattering mechanisms of the 2DEGs. In addition, this review examines the substantial contributions of Molecular Beam Epitaxy (MBE) to these developments, particularly through advancements in vacuum technology, source material purification, and precision control of growth conditions. The intent of this review is to serve as a useful reference for researchers and practitioners in the field, offering insights into the historical progression and technical details of these semiconductor systems. [ABSTRACT FROM AUTHOR]

Gallium nitride (GaN)‐based semiconductor laser diodes (LDs) have garnered significant attention due to their promising applications. However, high‐power LDs face serious degradation issues that limit their practical use. This study investigates the degradation factors of 437 nm and 6.3 W LDs by comparing light–current–voltage (L–I–V) characteristics, transmission electron microscopy (TEM), cathodoluminescence (CL), and secondary ion mass spectroscopy (SIMS) before and after 1000‐h aging. The diffusion of mirror coating from the resonant cavity surface is identified as a key factor contributing to high‐power LD degradation, which has not been reported in milliwatt‐level LDs. Meanwhile, the mechanisms behind the LD degradation are profiled and summarized together with the diffusion and other factors. On basis of the mechanism exploration, an anti‐aging technology for high‐power GaN‐based LDs is developed by using aluminum nitride for passivation layer and sapphire materials for mirror film. This anti‐aging technology has been verified, and a nearly ten‐time degradation suppression is achieved from 1000 h. This study elucidates the degradation mechanisms of high‐power GaN LDs and provides an effective technology to extend their lifespan, thereby prompting the practical applications of high‐power LDs.

The development of tunable photonic devices is strategic for miniaturized optical instrumentation and sensing systems. Exploiting the birefringence variation of liquid crystals (LCs) instead of MEMS actuation in such devices could bring better spectral stability and lower power consumption. However, aligning LCs inside a III–V semiconductor device is tricky. We demonstrate that self-assembled gallium arsenide (GaAs) quantum dashes (QDHs) could serve as direct planar aligners for LC nematic molecules. The alignment quality and birefringence variation of a LC-microcell embedding QDHs are shown to be similar to those of a polymer nanograting-based reference, with the added advantage of better electrical performance.

InAs/AlSb quantum cascade detectors (QCDs) grown strain-balanced on GaSb substrates are presented. This material system offers intrinsic performance-improving properties, like a low effective electron mass of the well material of 0.026 m0, enhancing the optical transition strength, and a high conduction band offset of 2.28 eV, reducing the noise and allowing for high optical transition energies. InAs and AlSb strain balance each other on GaSb with an InAs:AlSb ratio of 0.96:1. To regain the freedom of a lattice-matched material system regarding the optimization of a QCD design, submonolayer InSb layers are introduced. With strain engineering, four different active regions between 3.65 and 5.5 µm were designed with InAs:AlSb thickness ratios of up to 2.8:1, and subsequently grown and characterized. This includes an optimized QCD design at 4.3 µm, with a room-temperature peak responsivity of 26.12 mA/W and a detectivity of 1.41 × 108 Jones. Additionally, all QCD designs exhibit higher-energy interband signals in the mid- to near-infrared, stemming from the InAs/AlSb type-II alignment and the narrow InAs band gap. [ABSTRACT FROM AUTHOR]

Abstract The authors report a novel structure to improve the high‐frequency performance of nitrogen‐polar GaN deep‐recess high electron mobility transistors (HEMTs) wherein a timed plasma etch was used to tailor the profile of the gate dielectric. A favourable trade‐off between gate fringing capacitance and transconductance was established, resulting in an improved current gain cutoff frequency times gate length (ft·LG) figure of merit compared to standard Schottky‐gate and metal‐insulator‐semiconductor (MIS) HEMTs. The etched gate dielectric MISHEMT demonstrated a maximum ft·LG of 15.0 GHz·µm for an LG of 100 nm.

Abstract Semiconductor wafer manufacturing relies on the precise control of various performance metrics to ensure the quality and reliability of integrated circuits. In particular, GaN has properties that are advantageous for high voltage and high frequency power devices; however, defects in the substrate growth and manufacturing are preventing vertical devices from performing optimally. This paper explores the application of machine learning techniques utilizing data obtained from optical profilometry as input variables to predict the probability of a wafer meeting performance metrics, specifically the breakdown voltage (Vbk). By incorporating machine learning techniques, it is possible to reliably predict performance metrics that cause devices to fail at low voltage. For diodes that fail at a higher (but still below theoretical) breakdown voltage, alternative inspection methods or a combination of several experimental techniques may be necessary.

Density-functional theory calculations on P-rich InP(001):H surfaces are presented. Depending on temperature, pressure and substrate doping, hydrogen desorption or adsorption will occur and influence the surface electronic properties. For p-doped samples, the charge transition levels of the P dangling bond defects resulting from H desorption will lead to Fermi level pinning in the lower half of the band gap. This explains recent experimental data. For n-doped substrates, H-deficient surfaces are the ground-state structure. This will lead to Fermi level pinning below the bulk conduction band minimum. Surface defects resulting from the adsorption of additional hydrogen can be expected as well, but affect the surface electronic properties less than H desorption.

The authors report a novel structure to improve the high‐frequency performance of nitrogen‐polar GaN deep‐recess high electron mobility transistors (HEMTs) wherein a timed plasma etch was used to tailor the profile of the gate dielectric. A favourable trade‐off between gate fringing capacitance and transconductance was established, resulting in an improved current gain cutoff frequency times gate length (ft·LG) figure of merit compared to standard Schottky‐gate and metal‐insulator‐semiconductor (MIS) HEMTs. The etched gate dielectric MISHEMT demonstrated a maximum ft·LG of 15.0 GHz·µm for an LG of 100 nm. [ABSTRACT FROM AUTHOR]

Semiconductor wafer manufacturing relies on the precise control of various performance metrics to ensure the quality and reliability of integrated circuits. In particular, GaN has properties that are advantageous for high voltage and high frequency power devices; however, defects in the substrate growth and manufacturing are preventing vertical devices from performing optimally. This paper explores the application of machine learning techniques utilizing data obtained from optical profilometry as input variables to predict the probability of a wafer meeting performance metrics, specifically the breakdown voltage (Vbk). By incorporating machine learning techniques, it is possible to reliably predict performance metrics that cause devices to fail at low voltage. For diodes that fail at a higher (but still below theoretical) breakdown voltage, alternative inspection methods or a combination of several experimental techniques may be necessary. [ABSTRACT FROM AUTHOR]

Au nanoparticles (NPs) were designed to be embedded into III-V semiconductors to form Au/GaAs Schottky heterostructures, which were used as top-modified cover layers for quantum dot semiconductor saturable absorption mirrors (QD-SESAMs). By harnessing the distinctive localized surface plasmon resonance (LSPR) effect exhibited by Au NPs, a remarkable enhancement in photogenerated carrier concentration is achieved at the heterojunction interface. Consequently, this leads to a significant improvement in the nonlinear optical characteristics of the device. The modulation depth (MD) and saturation fluence of the device are optimized from the initial 2.2% and 16.1 MW/cm2 to 2.8% and 8.3 MW/cm2, respectively. Based on the optimized device, a Q-switched laser has been developed with an impressive output power of 17.61 mW and a single pulse energy of 274.9 nJ. These results unequivocally showcase the exceptional advantages offered by utilizing Au NPs to optimize the nonlinear optical characteristics of III-V semiconductor devices, thereby highlighting its immense potential for practical applications in various fields. [ABSTRACT FROM AUTHOR]

Density-functional theory calculations on P-rich InP(001):H surfaces are presented. Depending on temperature, pressure and substrate doping, hydrogen desorption or adsorption will occur and influence the surface electronic properties. For p-doped samples, the charge transition levels of the P dangling bond defects resulting from H desorption will lead to Fermi level pinning in the lower half of the band gap. This explains recent experimental data. For n-doped substrates, H-deficient surfaces are the ground-state structure. This will lead to Fermi level pinning below the bulk conduction band minimum. Surface defects resulting from the adsorption of additional hydrogen can be expected as well, but affect the surface electronic properties less than H desorption. [ABSTRACT FROM AUTHOR]

In this work, 1 eV Ga0.7In0.3As inverted metamorphic (IMM) solar cells were analyzed to achieve a deeper understanding of the mechanism limiting their improvement. For this purpose, high-resolution X-ray diffraction (HRXRD), transmission electron microscopy (TEM), high-resolution cross-sectional cathodoluminescence (CL), and transient in situ surface reflectance were carried out. Additionally, the photovoltaic responses of the complete devices were measured using the external quantum efficiency (EQE) and numerically simulated through Silvaco TCAD ATLAS. The combination of structural characterization of the semiconductor layers and measurements of the solar cell photovoltaic behavior, together with device modeling, allows us to conclude that the lifetime of the bulk minority carriers is the limiting factor influencing the PV response since the recombination at the interfaces (GaInP window–GaInAs emitter and GaInAs base–GaInP back surface field (BSF)) does not impact the carrier recombination due to the favorable alignment between the conduction and the valance bands. The advanced characterization using cross-sectional cathodoluminescence, together with transient in situ surface reflectance, allowed the rejection of the formation of traps related to the GaInAs growth conditions as being responsible for the decrement in the minority-carrier lifetime. Conversely, the TEM and HRXRD revealed that the presence of misfit dislocations in the GaInAs layer linked to strain relaxation, which were probably formed due to an excessive tensile strain in the virtual substrate or an incorrect combination of alloy compositions in the topmost layers, was the dominant factor influencing the GaInAs layer's quality. These results allow an understanding of the contributions of each characterization technique in the analysis of multi-junction solar cells. [ABSTRACT FROM AUTHOR]

III-V compound semiconductors are widely used for electronic and optoelectronic applications. However, interfacing III-Vs with other materials has been fundamentally limited by the high growth temperatures and lattice-match requirements of traditional deposition processes. Recently, we developed the templated liquid-phase (TLP) crystal growth method for enabling direct growth of shape-controlled single-crystal III-Vs on amorphous substrates. Although in theory, the lowest temperature for TLP growth is that of the melting point of the group III metal (e.g., 156.6 °C for indium), previous experiments required a minimum growth temperature of 500 °C, thus being incompatible with many application-specific substrates. Here, we demonstrate low-temperature TLP (LT-TLP) growth of single-crystalline InP patterns at substrate temperatures down to 220 °C by first activating the precursor, thus enabling the direct growth of InP even on low thermal budget substrates such as plastics and indium-tin-oxide (ITO)-coated glass. Importantly, the material exhibits high electron mobilities and good optoelectronic properties as demonstrated by the fabrication of high-performance transistors and light-emitting devices. Furthermore, this work may enable integration of III-Vs with silicon complementary metal-oxide-semiconductor (CMOS) processing for monolithic 3D integrated circuits and/or back-end electronics.

Abstract Experimental data on analog performance of gate‐all‐around III‐V vertical Tunnel Field‐Effect Transistors (TFETs) and circuits are presented. The individual device shows a minimal subthreshold swing of 44 mV/dec and transconductance efficiency of 50 V−1 for current range of 9 nA/μm to 100 nA/μm and at a drain voltage of 100 mV. This TFET demonstrates translinearity between transconductance and drain current for over a decade of current, paving way for low power current‐mode analog IC design. To explore this design principle, a current conveyor circuit is implemented, which exhibits large‐signal voltage gain of 0.89 mV/mV, current gain of 1nA/nA and an operating frequency of 320 kHz. Furthermore, at higher drain bias of 500 mV, the device shows maximum transconductance of 72 μS/μm and maximum drain current of 26 μA/μm. The device, thereby, can be operated as a current mode device at lower bias voltage and as voltage mode device at higher bias voltage.

Au nanoparticles (NPs) were designed to be embedded into III-V semiconductors to form Au/GaAs Schottky heterostructures, which were used as top-modified cover layers for quantum dot semiconductor saturable absorption mirrors (QD-SESAMs). By harnessing the distinctive localized surface plasmon resonance (LSPR) effect exhibited by Au NPs, a remarkable enhancement in photogenerated carrier concentration is achieved at the heterojunction interface. Consequently, this leads to a significant improvement in the nonlinear optical characteristics of the device. The modulation depth (MD) and saturation fluence of the device are optimized from the initial 2.2% and 16.1 MW/cm2 to 2.8% and 8.3 MW/cm2, respectively. Based on the optimized device, a Q-switched laser has been developed with an impressive output power of 17.61 mW and a single pulse energy of 274.9 nJ. These results unequivocally showcase the exceptional advantages offered by utilizing Au NPs to optimize the nonlinear optical characteristics of III-V semiconductor devices, thereby highlighting its immense potential for practical applications in various fields.

In photovoltaic (PV) power generation, highly efficient III-V solar cells are promising for emerging mobile applications, such as vehicle-integrated PVs. Although hydride vapor phase epitaxy (HVPE) has received attention due to its lower fabrication costs, realization of high throughput performance while maintaining solar-cell characteristics using this growth method is essential. In this study, the effect of atmospheric-pressure triple-chamber HVPE growth conditions on GaAs solar-cell properties were carefully investigated in conjunction with defect analysis using deep-level transient spectroscopy (DLTS). Based on the analysis on GaAs reaction processes, the suppression of arsine thermal cracking in the HVPE hot-wall reactor was important to achieve fast GaAs growth using a low input V/III ratio. Moreover, the DLTS results revealed that the reduced input V/III ratio was effective in suppressing the generation of EL2 traps, which is a common GaAs midgap complex defect involving arsenic antisites. Although the EL2 trap density increased with the growth rate, the performance of GaAs solar cells that were grown under reduced arsine thermal cracking exhibited almost no considerable cell parameter deterioration at a growth rate of up to 297 μm/h. Consequently, a conversion efficiency of 24% with a high open-circuit voltage of 1.04 V was achieved for the cells that were grown at 200 μm/h. [ABSTRACT FROM AUTHOR]

Recently, mixed crystal semiconductors containing BAs:N have garnered significant attention for the next generation of photovoltaic applications owing to their optoelectronic and elastic properties with moderate energy band gap (Eg). According to Vegard's law, lattice constants undergo slight variations under various condensation conditions. When Born–Huang (BH) stability criteria were applied to determine elastic parameters, the calculated Eg value of BAs1−xNx decreased concerning the increase in As condensation. It was found that these elastic constant values easily fulfilled the BH stability criteria, mechanically stabilizing BAs1−xNx. Moreover, the elastic moduli, Poisson's ratio and other properties were calculated. Our results suggest that BAs1−xNx compounds are ideal candidates for utilization in the above devices. Additionally, the calculated optical properties of this alloy indicated that BAs1−xNx is suitable for practical photo-sensing and photovoltaic applications due to its vast spectral region ranging from ultra-violet to visible, higher absorption peaks, and overall Eg values. The study provides a route for experimental work on photovoltaic applications based on cubic semiconductors. [ABSTRACT FROM AUTHOR]

A study is conducted on the nucleation process of aluminum droplets on a GaAs(001) surface during droplet epitaxial growth, which reveals the influencing factors in the nucleation process, including the substrate temperature and the deposition rate, when other conditions are unchanged. In addition, the minimum atomic number for the initially incomplete state, the initially completed state and the completed state are calculated to be 1, 2 and 5, respectively. In the meantime, based on the extended thermodynamic model, the energy E r and ideal contact angle θ 0 in the process of droplet ripening and nucleation are 2.5 eV and 73.5°. [ABSTRACT FROM AUTHOR]

Abstract This paper investigated the back‐barrier (BB) effect for gallium nitride (GaN)‐based high‐electron‐mobility transistors with an Fe‐doped buffer and Fe‐buffer + Indium gallium nitride (InGaN)‐BB structure. The authors found that the Fe‐doped buffer + InGaN‐BB structure was effective in reducing the off‐state leakage current compared to the Fe‐doped buffer. Secondary‐ion‐mass spectrometry measurements revealed that the segregated Fe existed with peaks at ∼2 × 1017 cm−3 around the InGaN‐BB layer. The authors believe that the negative charges which are generated by Fe effectively increased the BB effect as they exist just underneath the 2‐dimensional‐electron‐gas channel and successfully achieved a high output power operation of 4.6 W/mm at 94 GHz.

Abstract Interfaces are key elements that define electronic properties of the final device. Inevitably, most of the active interfaces of III–V semiconductor devices are buried and it is therefore not straightforward to characterize them. The Tapered Cross Section Photoelectron Spectroscopy (TCS‐PES) approach is promising to address such a challenge. That the TCS‐PES can be used to study the relevant heterojunction in epitaxial III–V architectures prepared by metalorganic chemical vapor deposition is demonstrated here. A MULTIPREP polishing system that enables controlling the angle between the sample holder and the polishing plate has been employed to improve the reproducibility of the polishing procedure. With this procedure, that preparing the TCS of III–V semiconductor devices with tapering angles lower than 0.02° is possible is demonstrated. The PES provides then information about the buried interfaces of Ge|GaInP and GaAs|GaInP layer stacks. Both, chemical and electronic properties have been measured by PES. It evidences that the preparation of the TCSs under an uncontrolled atmosphere modifies the pristine properties of the critical buried heterointerfaces. Surface states and reaction layers are created on the TCS surface, which restrict unambiguous conclusions on buried interface energetics.

We investigate in detail the role of strain relaxation and capping overgrowth in the self-assembly of InAs quantum dots by droplet epitaxy. InAs quantum dots were realized on an In 0.6 Al 0.4 As metamorphic buffer layer grown on a GaAs(111)A misoriented substrate. The comparison between the quantum electronic calculations of the optical transitions and the emission properties of the quantum dots highlights the presence of a strong quenching of the emission from larger quantum dots. Detailed analysis of the surface morphology during the capping procedure show the presence of a critical size over which the quantum dots are plastically relaxed. [ABSTRACT FROM AUTHOR]

Abstract This work presents a gallium nitride (GaN) high electron mobility transistor (HEMT)–based cascaded multistage power amplifier (MPA) in class‐AB for L‐band radar applications. The purpose of this endeavour is to develop an MPA using GaN HEMT devices to achieve optimised parameters such as high gain, high power, better efficiency, and linearity in a compact size. In an MPA design with multiple stages, oscillations are common owing to unwanted high gain at the lower frequency range. To overcome this issue, we introduced interstage harmonic termination networks as a novel approach to suppress high gain at low frequencies, which are prone to oscillations. The proposed cascaded MPA provides the maximum radio‐frequency output power of 89 W and a power gain of 52 dB with an associated power‐added efficiency of 51%. Second and third harmonic levels are −32.5 and −37 dBc, respectively. Two‐tone measurements are performed with a frequency separation of 10 MHz, and an intermodulation level of less than −33 dBc is achieved.

Experimental data on analog performance of gate‐all‐around III‐V vertical Tunnel Field‐Effect Transistors (TFETs) and circuits are presented. The individual device shows a minimal subthreshold swing of 44 mV/dec and transconductance efficiency of 50 V−1 for current range of 9 nA/μm to 100 nA/μm and at a drain voltage of 100 mV. This TFET demonstrates translinearity between transconductance and drain current for over a decade of current, paving way for low power current‐mode analog IC design. To explore this design principle, a current conveyor circuit is implemented, which exhibits large‐signal voltage gain of 0.89 mV/mV, current gain of 1nA/nA and an operating frequency of 320 kHz. Furthermore, at higher drain bias of 500 mV, the device shows maximum transconductance of 72 μS/μm and maximum drain current of 26 μA/μm. The device, thereby, can be operated as a current mode device at lower bias voltage and as voltage mode device at higher bias voltage. [ABSTRACT FROM AUTHOR]

The authors propose criteria for recess etching to fabricate T‐gate used in InGaAs high electron mobility transistors (HEMTs). By patterning additional rectangular pads on the source and drain metals in the e‐beam lithography step, it is possible to measure the drain‐to‐source resistance (Rds) and current (Ids). The ratio (Γ) of before and after etching for each Rds and Ids can be used as criteria to determine the point in time to stop etching. By performing recess etching with Γ= 1.97 for Rds and Γ= 0.38 for Ids on an epiwafer having cap doping concentration of 2 × 1019 cm−3 and channel indium content of 0.7, the authors have fabricated InGaAs metamorphic high electron mobility transistor (mHEMT) device showing gm,max= 1603 mS/mm and ft= 290 GHz at Lg= 124 nm. The criteria presented can be applied to InGaAs HEMTs with various epitaxial structures. [ABSTRACT FROM AUTHOR]

Group III–V semiconductors are based on the elements of groups III and V of the periodic table. The possibility to grow thin-films made of binary, ternary, and quaternary III–V alloys with different fractions of their constituent elements allows for the precise engineering of their optical properties. In addition, since many III–V compounds are direct-bandgap semiconductors, they are suitable for the development of photonic devices and integrated circuits, especially when monolithic integration is required. Moreover, the strong optical nonlinearities of III–V materials enable a fertile field of research in photonic devices for all-optical signal processing, wavelength conversion, and frequency generation. Experimentally accessing the plethora of nonlinear optical phenomena in these materials considerably facilitates the exploration of light-matter interactions. Several demonstrations have explored the optical nonlinearities in waveguides, microring resonators, photonic crystal structures, quantum dots, and lasers. In this review, we survey numerous nonlinear optical studies performed in III–V semiconductor waveguide platforms. In particular, we discuss linear and nonlinear optical properties, material growth and fabrication processes, newer hybrid material platforms, and several nonlinear optical applications of III–V semiconductor integrated optical platforms.

Abstract This article applies a systematic approach based on the normalized determinant function (NDF) theory to analyse stability in multi‐loop circuits and to design the required stabilization network. Presenting several provisions, the return ratios are extracted by employing immittance or hybrid matrices (Z, Y, G or H) of active two ports. Using these matrices, instead of the S‐parameters, facilitates the selection of an appropriate stabilizer network. As a practical case, a non‐uniform distributed amplifier (NDA) is designed and inspected for potential instabilities. The presented procedure detects instability associated with one of the NDA circuit's loops, and an appropriate stabilization circuit is accordingly devised. In order to validate the procedure, the designed NDA is implemented in a 0.1‐μm GaAs pHEMT process. As predicted, the measurements show oscillations, once the on‐chip stabilization circuit is disabled.

III-V semiconductor lasers are ubiquitous in modern optoelectronic devices, with applications ranging from telecommunication to general lighting. Among the different kinds of laser cavity designs, whispering-gallery mode (WGM) micro-cavity lasers boast outstanding optical performance due to advantages such as ultra-high Q-factor, compact mode volume, and narrow emission linewidth. Over the past decades, research in III-V WGM micro-cavity lasers has progressed rapidly in various aspects, including the fabrication techniques, emission outcoupling methods, and practical applications. In this paper, a comprehensive review is performed on the advances in these aspects. Although III-V WGM lasers are conventionally fabricated with top-down approaches, recent reports have demonstrated the potential of highly-scalable bottom-up methods in fabricating low-loss WGM lasers. Despite the strong optical confinement in III-V WGM cavities, various techniques have been developed to either outcouple WGM emission into waveguides or direct it into free-space with small beam divergence. Finally, recent developments in different applications of III-V WGM micro-cavity lasers are discussed. Other than serving as integrated photonic components, III-V WGM lasers have also displayed exciting potential in other applications such as label-free sensing and the study of cavity quantum electrodynamics (cQED). [ABSTRACT FROM AUTHOR]

Abstract A reliable small‐signal modelling approach has been developed and applied on GaN‐on‐diamond high electron mobility transistor. The extrinsic elements' extraction procedure was improved to provide an accurate characterization for the quasistatic behaviour of the intrinsic transistor. The frequency independence of the intrinsic elements at active multibias condition has been considered as another objective in addition to measurements' fitting. Physical relevant values for the model elements have been obtained. The model accuracy was also validated by means of S‐parameters simulation, which showed a very good fitting of the measured data.

Abstract In this work, the boron nitride (BN) nanosheets were dispersed in natural esters to fabricate the dielectric nanofluid. Microstructures and chemical compositions of the nanosized BN are determined. The stability, viscosity, and thermal conductivity of the BN nanofluid, were obtained. And the dissipation factor, electrical conductivity, and relative permittivity of the BN nanofluid, were measured. The ion mobilities and migrating times of the nanofluid were measured under different volumetric fractions of BN nanosheets and temperatures. Results show that the electrical conductivity and dissipation factor of the nanofluid decreased by 54% and 48% with the addition of only 0.1% of BN nanosheets under 110°C. Both the half‐reduced carrier mobility of the nanofluid and the declined ion concentration by blocking of BN nanosheet contributed to the exponentially reduced electrical conductivity and enhanced dielectric performances of the BN nanofluid. The suppression coefficient k is proposed to quantitatively describe the hinder effect of ion migration in nanofluids by 2D BN nanosheet. Results provide a strategy to design and develop advanced nanofluids with low‐dielectric loss by aids of surface adsorption of ion and steric hindrance of 2D nanosheets.

The ongoing energy transition to curb carbon dioxide emissions and meet the increasing energy demands have enhanced the need for integration of renewable energy into the existing electricity system. Solar energy has been gaining an increasing market share over the past decade. Multi-junction solar cells (MJSCs) enable the efficient conversion of sunlight to energy without being bound by the 33% limit as in the commercialized single junction silicon solar cells. III-V semiconductors have been used effectively in space applications and concentrated photovoltaics (CPV) over the past few decades. This review discusses the working and components of MJSCs at cell level as well as module level for space applications and CPV. The fabrication procedure, material acquirement of MJSCs is analyzed before introducing the current challenges preventing MJSCs from achieving widespread commercialization and the research direction in the future where these challenges can be addressed.