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Abstract: We report high output power from AlInGaN multiple quantum well (MQW) ultraviolet light-emitting diodes. The high Al containing cladding layer, electron blocking layer and p-contact layer were chosen for transparency at 365nm to reduce the internal absorption, reduce electron overflow and enhance output power. The UV output power was as high as 1.52mW at 20mA at 368nm under room temperature CW operation. The maximum output power in CW operation is 11mW at 170mA. In this letter, we demonstrate a helpful and easy way to measure and calculate the junction temperature of AlInGaN UVLEDs. [Copyright &y& Elsevier]

In this article, the laser performance of the 1300-nm In0.4Ga0.6As0.986N0.014/GaAs1−xNx quantum-well (QW) lasers with various GaAs1−xNx strain compensated barriers (x=0%, 0.5%, 1%, and 2%) has been numerically investigated with a laser technology integrated simulation program. The simulation results suggest that with x=0% and 0.5% can have better optical gain properties and high characteristic temperature coefficient T0 values of 110 and 94 K at the temperature range of 300–370 K. As the nitrogen composition in GaAs1−xNx barrier increases more than 1% the laser performance degrades rapidly and the T0 value decreases to 87 K at temperature range of 300–340 K. This can be attributed to the decrease of conduction band carrier confinement potential between In0.4Ga0.6As0.986N0.014 QW and GaAs1−xNx barrier and the increase of electronic leakage current. Finally, the temperature dependent electronic leakage current in the InGaAsN/GaAs1−xNx quantum-well lasers are also investigated. [Copyright &y& Elsevier]

The characteristics of amorphous Sn-doped Ga 2 O 3 films deposited using radio frequency magnetron sputtering at room temperature under different sputter powers have been demonstrated. A balance mechanism of energy supply and ion bombardment controlled by sputter power has been found during the deposition. The increasing growth rate as power can be due to the increased yield sputtering species indicated by an in situ optical emission spectroscopy. As the power increases to 700 W, an obvious change from discrete nanoparticles to flat-continuous film can be observed because of sufficient energy supply for oxidation reaction, which leads to the maximum ratio of lattice oxygen and Sn4+ indicating the optimal film quality and conductive property. However, a non-negligible high energy ion bombardment presented at 900 W leads to the degraded film quality. The influence of sputtering power on Sn-doped Ga 2 O 3 solar-blind photodetectors is demonstrated. It can obtain a good performance with an ultra-low dark current density of 2.2 × 10−11 A/cm2, a substantial light-dark current ratio of 1.08 × 103 and fast rise/decay time of 1.59 s/0.54 s at 700 W. The revelation of the role of sputtering power on the properties of Sn-doped Ga 2 O 3 films may offer an interesting direction for low-cost and high-performance solar-blind photodetectors. • The characteristics of amorphous Sn-doped Ga 2 O 3 films deposited using RFMS at RT under different sputter powers from 100 to 900 W have been investigated. A balance mechanism of energy supply and ion bombardment controlled by sputter power has been proposed during the film's deposition. • As The power increases to 700 W, an obvious change from discrete nanoparticles to flat-continuous film can be observed, which may be attributed to sufficient migration energy and enhanced oxidation reaction. • A non-negligible high energy ionized particles bombardment effect is presented at 900 W leading to the degraded surface morphology and film quality. • The influence of sputtering power on Sn-doped Ga 2 O 3 solar-blind PDs is demonstrated. It can obtain a good performance with an ultra-low dark current density of 2.2 × 10−11 A/cm2, a substantial switch ratio of light-dark current of 1.08 × 103 and fast photoresponse rise/decay time of 1.59 s/0.54 s at 700 W. [ABSTRACT FROM AUTHOR]

• Using a Shortcut to Adiabatic (STA) approach to achieve specific high order modes coupling in the waveguide and generate SCG. • Compared to conventional angle tilting edge coupling (<7%) for high order mode, the coupling efficiency over 80 % for specific high order mode from fundamental mode in the broadband spectrum was recorded and demonstrated, confirming the functionality of mode coupling. The observed octave spanning SCG (at level of 30 dB span nearly 600 nm) from TE 10 mode was characterized. • The fabrication tolerance r for waveguide width variations of ± 13 nm is constant with only slight changes (less than 10 %). • This is first time, to our best knowledge, the efficient octave spanning SCG can be generated from specific high order within nonlinear waveguide. Broadband optical sources have been attracting widespread attention because of their remarkable potential for application to quantum technology. One of the major obstacles to realization of such applications is the weak anomalous group velocity dispersion (GVD) of these sources and low coupling efficiency of high order mode for generating supercontinuum generation (SCG). In this work, using a shortcut to adiabaticity (STA) approach, high order modes can be excited selectively with coupling efficiency of more than 80 % to enable octave spanning supercontinuum generation within a waveguide composed of tantalum pentoxide (Ta 2 O 5), which is a high nonlinear refractive index material. The SCG over the range from 650 nm to 1300 nm, which corresponds to one octave, was demonstrated and analyzed when the material was pumped using a femtosecond laser with a center wavelength of 1030 nm. [ABSTRACT FROM AUTHOR]

• Study examines field plate configurations' impact on GaN MIS-HEMT breakdown voltage. • The study stresses composite field plates(e.g. gate with source and drain) to maximize breakdown voltage. • The device performance is further enhanced by using a stacked field plate configuration. • Study explores high-k dielectric passivation effects with field plate configuration on device breakdown voltage. The effects of different field plate designs on the breakdown voltage of GaN Metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) were examined in this study. The study's primary goal was to determine the dependence of breakdown voltage with respective to composite field plate designs using TCAD simulation. For devices featuring only G-FP, with a fixed gate to drain distance of 15 μm and a fixed G-FP to drain distance of 15 μm, the maximum breakdown voltage was achieved 1 μm G-FP. Breakdown voltage trends were also determined for composite field plate configurations, such as adding a source field plate (S-FP) or a drain field plate (D-FP) with a fixed 1 μm G-FP length. A further enhancement in device breakdown performance was demonstrated by employing a novel D-FP structure. A single D-FP improves the breakdown voltage from 1.4 kV (conventional breakdown voltage with 1um G-FP) to 1.6 kV when combined with 1 μm G-FP, while the novel two-step D-FP achieves a breakdown voltage of about 1.7 kV when combined with 1 μm G-FP. We also investigated the influence of high-k dielectric passivation layers on the breakdown voltage. The breakdown voltage of the devices with optimized G-FP can be further improved by using high-k dielectric material as a passivation layer. The thorough investigations contribute to a better understanding of GaN MIS-HEMT breakdown characteristics and prospective pathways for improving their performance via unique field plate designs and superior dielectric materials. [ABSTRACT FROM AUTHOR]

• Implementing higher-order mode SCG in waveguides using edge coupling. • Achieving more than 200 nm (−30 dB level) of spectrum broadening using pulse energy of ten pJ. • Choosing a Ti:sapphire femtosecond laser to extend its spectrum into the visible range for more applications. Broadband optical sources emitting low pulse energy have attracted significant attention owing to their remarkable potential for quantum technology. One of the obstacles to achieving this objective is the weak anomalous dispersion. In this study, supercontinuum generation (SCG) from 645.3 nm to 851 nm pumped by a Ti:sapphire femtosecond laser at a center wavelength of 800 nm is demonstrated by using a high-order mode (transverse electric TE 20) and engineering the dispersion within the high nonlinear refractive index material, the tantalum pentoxide (Ta 2 O 5) waveguide. The total on-chip average pulse energy of around few pJ used to excite SCG shows clear future for applications. [ABSTRACT FROM AUTHOR]

In this work, the time-dependent dielectric breakdown (TDDB) analysis is performed to understand the gate oxide reliability in SiC MOSFETs with two different structures, i.e., planar and trench gate structures. We have discovered different gate leakage current behaviors between the SiC MOSFETs with planar gate (Sample A) and trench gate (Sample B) during the forward gate bias stress. Notably, the slight increase of the gate current during the stress and the negative activation energy (E a = −0.07 eV) observed in Sample A suggest that the hole generation caused by the impact ionization can be occurred during the forward gate TDDB tests. Furthermore, the SiC MOSFETs with trench gate structure (Sample B) exhibit the operation voltage of 55.7 V (exponential law) and 57.3 V (power law) for the 0.001 % failure of 30 years under 175 °C, indicating that SiC trench gate MOSFETs with enough thick gate dielectric (87.1 nm (bottom) and 77.9 nm (sidewall)) can have the promising forward gate TDDB stability. • The time-dependent dielectric breakdown (TDDB) analysis is performed to understand the gate oxide reliability in SiC MOSFETs • Different gate leakage current behaviors between the SiC MOSFETs with planar gate and trench gate • The negative activation energy observed in SiC planar MOSFETs suggests that the hole generation caused by the impact ionization • SiC trench gate MOSFETs with enough thick gate dielectric can have the promising forward gate TDDB stability. [ABSTRACT FROM AUTHOR]

Visible wavelength light-emitting diodes (LEDs) and laser diodes (LDs) enabled optical wireless communication (OWC) is an emerging technology for realizing high-confidentiality and high-speed point-to-point (PtP), vehicle-to-vehicle, and white-lighting data access links in indoor/outdoor free-space and underwater environments. Notably, OWC facilitates users to access more transmission bandwidth and capacity with physical-layer security and electromagnetic-immunity features by utilizing unlicensed visible optical carriers bands covering from 400 to 800 THz as compared to the commonly employed radio-frequency bands. Hence, a large amount of heavy data exchanging, routing, and streaming traffics can be realized in the current wireless networks. This also reinforces the realistic fusion of optical fiber wireline, radio-frequency wireless, and visible lighting communication networks in the new big-data era. In this paper, developing progress as well as the current trend of visible LED and LD based OWC networks for PtP, white-lighting and underwater applications are overviewed in detail. The performance parameters and figures-of-merits of previously reported OWC systems are summarized for comparison and discussion. Three main scenarios including visible LED based lighting OWC, visible LD enabled PtP communication, and LD based white-light fidelity ("Li-Fi") are individually discussed and summarized with their allowable data rate, transmission distance, and lighting color temperature and rendering index for comparison. At first, the transmission performances of LED based PtP and white-lighting OWC system with the use of novel data formats, such as pulse amplitude modulation and quadrature amplitude modulation-orthogonal frequency division multiplexing, are surveyed to understand the increasing trend on transmission capacity of LED based OWC system. Owing to the limited bandwidth and data rate of LED based OWC system, the LD has gradually been regarded as a competitive alternative candidate transmitter due to their significantly broadened bandwidth and enhanced data capacity. By taking the aforementioned advantages, studies on the blue/violet LD based white-lighting OWC have recently emerged to demonstrate the substitutability of this technology. The impacts of LD based OWC technology with its state-of-the-art implementation are comprehensively discussed together with prospects for future developments. Undoubtedly, the blue/violet LDs are also a promising transmitter for underwater PtP transmission owing to its extremely low power extinction in water, which has recently emerged as the most intriguing source for undersea exploration and sensing applications. [ABSTRACT FROM AUTHOR]

Toward finding low-cost electrocatalysts with high catalytic properties to replace noble metals as high efficient electrocatalysts in electrochemical hydrogen evolution reaction (HER) of total water splitting plays a vital role to approach the green and sustainable energy supply. Here, we demonstrate the direct growth of novel copper phosphide coated with amorphous carbon, namely heterostructured a-C/Cu 3 P peapod nanowires from chemically synthesized copper nanowires (Cu NWs) followed by a chemical vapor phosphorization reaction (CVPR) process at a low temperature of 400 °C. The heterostructured a-C/Cu 3 P peapod nanowires exhibit a superior electrocatalytic activity by a lower overpotential of 287 mV at a current density of 10 mA cm−2 with a low Tafel slope of 72 mV dec−1 and excellent stability over 1000 cycles. The superior electrocatalytic performance can be explained by the superior contact of the electrolyte with active sites on the heterostructured a-C/Cu 3 P due to the high surface area of peapod nanowire structure covered by defective edges of graphene with the encapsulated amorphous carbon layer, which can tremendously enhance electrical conductivity at the surface. The direct growth of novel copper phosphide coated with amorphous carbon, namely heterostructured a-C/Cu 3 P peapod nanowires from chemically synthesized copper nanowires (Cu NWs) followed by a chemical vapor phosphorization reaction (CVPR) process at a low temperature of 400 °C was demonstrated. Image 1 • The heterostructured a-C/Cu 3 P peapod NWs exhibit a superior electrocatalytic activity by a lower overpotential of 287 mV at a current density of 10 mA cm-2 with a low Tafel slope of 72 mV dec-1 and excellent stability over 1000 cycles • The superior electrocatalytic performance can be explained by the superior contact of the electrolyte with active sites on the heterostructured a-C/Cu 3 P due to the high surface area of peapod NWs covered by defective edges of graphene layers with the encapsulated amorphous carbon layer. • A theoretical study at the active sites of heterostructured a-C/Cu 3 P peapod NWs by density functional theory (DFT) was proposed. [ABSTRACT FROM AUTHOR]

GaN is a great material for making optoelectronic devices in the blue, blue-violet and green bands. Vertical-cavity surface-emitting lasers (VCSELs) have many advantages including small footprint, circular symmetry of output beam, two-dimensional scalability and/or addressability, surface-mount packaging, good price-performance ratio, and simple optics/alignment for output coupling. In this paper, we would like to (1) Review the design and fabrication of GaN-based VCSELs including some technology challenges, (2) Discuss the design and metalorganic chemical vapor deposition (MOCVD) growth of electrically pumped blue VCSELs and (3) Demonstrate world first green VCSEL using quantum dots (QDs) active region to overcome the 'green gap'. [ABSTRACT FROM AUTHOR]

Rigid protection layers for the lead-halide perovskite effectively enhance its stability. In this work, for the most vulnerable CsPbI 3 perovskite nanocrystals (PNCs), we introduced zero-dimensional perovskites Cs 4 PbI 6 for protection in addition to already robust SiO 2 all-inorganic encapsulation, via high-temperature solid-state synthesis. It is proven that the CsPbI 3 –Cs 4 PbI 6 nano-composite not only maintains the emission peak location of CsPbI 3 PeNCs at 700 nm with remarkable oxygen and water resistances, but also exhibits enhanced instant and long-term thermal stability compared with samples containing less amount of Cs 4 PbI 6. The passivation of defects on the interface of CsPbI 3 –Cs 4 PbI 6 contributes to the enhancement of photoluminescence quantum yield by 8%. These ultra stable CsPbI 3 –Cs 4 PbI 6 nano-composites show potentials in the application of luminous and display industries. • The CsPbI 3 –Cs 4 PbI 6 nano-composite is synthesized by high-temperature solid-state reaction method. • Samples have excellent thermal stability with the addition of ZnI 2. • Increased PLQY is corresponded to the passivation of defects on the interface. • Manifestation of carrier transitions between CsPbI 3 and Cs 4 PbI 6. [ABSTRACT FROM AUTHOR]

Photon management is essential in improving the performances of optoelectronic devices including light emitting diodes, solar cells and photo detectors. Beyond the advances in material growth and device structure design, photon management via nanoscaled phenomena have also been demonstrated as a promising way for further modifying/improving the device performance. The accomplishments achieved by photon management via nanoscaled phenomena include strain-induced polarization field management, crystal quality improvement, light extraction/harvesting enhancement, radiation pattern control, and spectrum management. In this review, we summarize recent development, challenges and underlying physics of photon management in GaN-based light emitting diodes and solar cells. [ABSTRACT FROM AUTHOR]

Tin doped indium oxide (ITO) film was prepared by high power impulse magnetron sputtering. The effects of power density on the compositional and structural evolution of the film were investigated. The higher power density was found to increase the Sn/In ratio due to the weakening of self-sputtering effect as the initial energy of sputtered species increases. The higher excitation/ionization rate of the oxygen species in the plasma at higher power density was found effective for passivating the oxygen vacancy defects and raising the Sn doping efficiency in ITO film. In addition, The higher power density also leads to the change of (2 2 2)-orientated grains to (4 0 0)-orientated grains, which is possibly due to the reduction of diffusion length and rising migration barrier of the deposited cations by increasing number of oxygen radicals. As the power density increases, the carrier concentration increases due to higher Sn content and Sn doping efficiency. The carrier mobility increases due to the crystal orientation change, passivation of oxygen vacancy defects and larger grain size. ITO film with resistivity of 4.1 × 10−3 Ω cm and transmittance of over 78% at 400–800 nm was obtained at a power density of 1.30 W/cm2. • ITO films are prepared by in-line high power impulse magnetron sputtering (HiPIMS) at room temperature. • An increase of Sn content and doping efficiency were observed as the average power increases at 0.52–1.56 W/cm2. • The crystal orientation of the film changes from (2 2 2) to (4 0 0) with increasing power density as observed by XRD. • The (4 0 0) orientated film has better electrical properties and rougher surface. • ITO film deposited at 1.30 W/cm2 has a low resistivity of 4.1 × 10−3 Ω cm and a high transmittance of > 78% at 400–800 nm. [ABSTRACT FROM AUTHOR]

Abstract: This work demonstrates hybrid InGaN/GaN multiple quantum well (MQW) solar cells with enhanced power conversion efficiency using colloidal CdS quantum dots (QDs) and back-side distributed Bragg reflectors (DBRs). CdS QDs can absorb ultraviolet (UV) photons, which are strongly absorbed by indium tin oxide (ITO), and they emit photons with a longer wavelength. This process improves the collection of photon-generated carriers and is known as the luminescence down-shifting (LDS). Accordingly, CdS QDs can compensate for the poor utilization of UV photons in an ITO layer, enhancing the external quantum efficiency (EQE) in the UV range. The DBRs on the back of the solar cells can reflect photons of longer wavelengths back into the absorber layer, increasing the EQE (380–440nm). The combination of CdS QDs and DBRs results in broadband EQE enhancement, and yields an overall power conversion efficiency that is 20.7% better than that of a reference device without CdS QDs and DBRs. [Copyright &y& Elsevier]

Abstract: This study investigates how to apply space-charge-limited (SCL) current to describe shunt leakage current in a CIGS solar cell. Possible factors inducing SCL current have been observed through conductive atomic force microscopy (C-AFM), which supports the SCL current theory, describing the shunt current of a CIGS solar cell. In simulations derived from experimental data, deviation of dark IV curves is due to flaws in the real device. These flaws are absent in simulation, but investigation verifies the characteristics of SCL current component's experimental IV curves within shunt leakage current. A device with a metal/CIGS/metal structure could simulate SCL current and confirm its characteristics. Such a simulated structure, representing flaws inserted into a CIGS solar cell, generates the same dark-current behavior revealed in experimental dark IV curves. This study investigates the response of dark current to varying sizes of the flaw within the CIGS solar cell. [Copyright &y& Elsevier]

Abstract: This study demonstrates the high performance of GaAs solar cells with dual-layer CdS quantum dots (QDs) carried by flexible polydimethylsiloxane (PDMS) film. Several parameters were enhanced, including the short circuit current, fill factor, and power conversion efficiency, which were measured under white light illumination similar to the solar spectrum. The flexible PDMS film was fabricated using the spin-coating technique, and was then used to embed dual-layer CdS QDs. Different concentrations of QDs were applied in this design to test the optimal combination. The proposed scheme enhances power conversion efficiency by 22%, compared to a GaAs solar cell without CdS QDs. The photon down-conversion capability in the ultraviolet (UV) range and additional anti-reflection capability in the longer visible-IR range were verified through the external quantum efficiency. [Copyright &y& Elsevier]

Abstract: Passivation plays a critical role in silicon photovoltaics, yet how a passivation layer affects the optical characteristics of nano-patterned surfaces has rarely been discussed. In this paper, we demonstrate conical-frustum nanostructures fabricated on silicon solar cells using polystyrene colloidal lithography with various silicon–nitride (SiN x ) passivation thicknesses. The omnidirectional and broadband antireflective characteristics were determined by utilizing angle-resolved reflectance spectroscopy. The conical-frustum arrays with a height of 550nm and a SiN x thickness of 80nm effectively suppressed the Fresnel reflection in the wavelength range from 400 to 1000nm, up to an incidence angle of 60°. As a result, the power conversion efficiency achieved was 13.39%, which showed a 9.13% enhancement compared to that of a conventional KOH-textured silicon cell. The external quantum efficiency measurements confirmed that the photocurrent was mostly contributed by the increased optical absorption in the near-infrared. The angular cell efficiencies were estimated and showed improvements over large angles of incidence. [Copyright &y& Elsevier]

Abstract: An InGaAs submonolayer (SML) quantum-dot photonic-crystal light-emitting diode (QD PhC-LED) with for fiber-optic applications is reported. The active region of the device contains three InGaAs SML QD layers. Each of the InGaAs SML QD layers is formed by alternate depositions of InAs (<1ML) and GaAs. A maximum CW output power of 0.34mW at 20mA has been obtained in the 980nm range. [Copyright &y& Elsevier]

Abstract: We report the synthesis of the In2O3 nanostructures grown at different growth temperatures by using the thermal evaporation method. The gold nanoparticles were used as the catalyst and were dispersed on the silicon wafer to facilitate the growth of In2O3 nanostructures. The nanostructures of the In2O3 were characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The photoluminescence study reveals that In2O3 nanostructures could emit different luminescence peaks in the range of 400–600nm with broad bands by adjusting different growth temperatures. The coverage of the wavelength tuning in the emission peaks of the In2O3 nanostructures could be beneficial for possible applications in white light illumination through manipulating the ratio of each wavelength component. [Copyright &y& Elsevier]

Abstract: We report the synthesis of the In2O3 nanoloquat grown at different oxygen flow rates by using the thermal evaporation method. The gold nanoparticles were used as the catalyst and were dispersed on the silicon wafer to facilitate the growth of In2O3 nanoloquats. The nanostructures of the In2O3 nanoloquats were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The photoluminescence (PL) study reveals that In2O3 nanoloquats could emit different luminescence peaks in the range of 500–600nm with broad bands by adjusting different oxygen flow rates. The coverage of the wavelength tuning in the emission peaks of the In2O3 nanoloquats could be beneficial for possible applications in white light illumination through manipulating the ratio of each wavelength component. [Copyright &y& Elsevier]

Abstract: Self-assembled inverted hexagonal pyramids with GaN:Mg and InGaN/GaN multi-quantum-well (MQW) structures were formed through photoelectrochemical wet etching. The formation mechanism of the inverted hexagonal pyramid consisted with a lateral etching process of the InGaN/GaN active layer, bottom-up etching process from N-face GaN direction, and anisotropic etching process. The photoluminescence (PL) intensity of GaN:Mg peak was enhanced in this inverted hexagonal pyramid caused by the quantum confinement effect of this nano-structure. These inverted hexagonal pyramids, consisting of the p-type GaN:Mg, nano-disk InGaN/GaN active layer, and n-type GaN:Si layer, are suitable for nano-scale optoelectronic devices. [Copyright &y& Elsevier]

Abstract: An InGaAs sub-monolayer (SML) quantum dot photonic crystal vertical-cavity surface-emitting laser (QD PhC-VCSEL) for fiber-optic applications is first time demonstrated. The active region of the device contains 3 InGaAs SML QD layers. Each of the InGaAs SML QD layer is formed by alternate deposition of InAs (<1ML) and GaAs. Single fundamental mode CW output power of 3.8mW at 28mA has been achieved in the 990nm range, with a threshold current of 0.9mA. Side-mode suppression ratio (SMSR) larger than 35dB has been demonstrated over entire current operation range. The beam profile study of the PhC-VCSEL indicates that the laser beam is well confined by the photonic crystal structure of the device. The divergence angle of the devices remains almost unchanged with increasing current. [Copyright &y& Elsevier]

Abstract: Transparent and conductive high-preferential c-axis-oriented Al-doped zinc oxide (ZnO:Al, AZO) thin films have been prepared by the sol–gel route. Film deposition was performed by spin-coating technique on Si(100) and glass substrate. Structural, electrical and optical properties were performed by XRD, SEM, four-point probe, photoluminescence (PL) and UV-VIS spectrum measurements. The effects of annealing temperature and dopant concentration on the structural and optical properties are well discussed. It was found that both annealing temperature and doping concentration alter the microstructures of AZO films. Also, PL spectra show two main peaks centered at about 380nm (UV) and 520nm (green). The variation of UV-to-green band emission was greatly influenced by annealing temperatures and doping concentration. Reduction in intensity ratio of UV-to-green might possibly originate from the formation of Al–O bonds and localized Al-impurity states. The minimum sheet resistance of 104 Ω/□ was obtained for the film doped with 1.6mol% Al, annealed at 750°C. Meanwhile, all AZO films deposited on glass are very transparent, between 80% and 95% transmittance, within the visible wavelength region. These results imply that the doping concentration did not have significant influence on transparent properties, but improve the electrical conductivity and diversify emission features. [Copyright &y& Elsevier]

Micro light-emitting diode (micro-LED) display, mainly based on inorganic GaN-based LED, is an emerging technique with high contrast, low power consumption, long lifetime and fast response time compared to liquid crystal display (LCD) and organic light-emitting diode (OLED) display. Therefore, many research institutes and companies have conducted in-depth research on micro-LED in the full-colour display, gradually realizing the commercialization of micro-LED. And the current research results of micro-LED indicate that it can be widely used in display, visible light communication (VLC), biomedicine and other fields. Although micro-LED has broad commercial prospects, it still faces great challenges, such as the effect of size reduction on performance, the realization of high-density integration on a single wafer for independent addressing of full-colour micro-LED display, the improvement of repair technique and yield et al. This paper reviews the key solutions to the technical difficulties of the full-colour micro-LED display. Specifically, this review analyzes and discusses a variety of advanced full-colour micro-LED display techniques with a focus on three aspects: growth technique, transfer printing technique and colour conversion technique. This review demonstrates the opportunities, progress and challenges of these techniques, aiming to guide the development of full-colour micro-LED display. [ABSTRACT FROM AUTHOR]

Metasurfaces are nanopatterned structures of sub-wavelength thickness. Their effective refractive index and spectral characteristic can be tailored by material composition, intrinsic and extrinsic resonances, structure size, and ambient conditions. Consequently, they allow for phase, amplitude, polarisation, and spatial control of an optical field beyond what natural materials can offer. Dielectric metasurfaces with lower loss have opened a wide range of new applications such as enhanced imaging, structural colour, holography, and planar sensors. In particular, beam steering and control measures such as nonlinear optics, ultrafast optics, and quantum optics are of increasing importance for quantum communication, computation, and information processing. In this review, the recent progress on dielectric metasurfaces is summarised, including advanced fabrication technologies and novel applications from advanced wavefront shaping to quantum platforms. In addition, a perspective for the future development of the field is presented. [ABSTRACT FROM AUTHOR]

Recent advances in the development of quantum dots (QDs) have offered new possibilities for the exploration of sensors, bio imaging, batteries, electrochemical water splitting and optoelectronic applications because of their intriguing optical, electrical, catalytic and electrochemical properties. Among QDs, atomically thin two-dimensional quantum dots (2D QDs) derived from graphene sheets, transition metal dichalcogenide (TMD) layers and phosphorene have been of considerable interest for the past few years. There have been several intensive studies of carbon QDs, but TMD QDs and heterostructures based on 2D QDs are rapidly advancing. Herein, the synthesis and properties of 2D QDs, particularly carbon and TMD QDs, are reviewed for the recent progress in their application toward electrochemical water splitting, photocatalytic wastewater treatment, supercapacitors, batteries and photodetectors. Moreover, the assembly of such 2D QDs to achieve industrial-scale production and boost their performance in widespread applications is emphasized. [ABSTRACT FROM AUTHOR]