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The passivation effects of sulfur treatment and Al2O3 passivation for AlGaInP/GaInP red micro-light-emitting-diodes (LEDs) were investigated in terms of the external quantum efficiency (EQE) and the current density showing the peak EQE (JEQE, peak). We systematically compared the electrical and optical characteristics of the micro-LEDs with and without passivation according to various sizes. Interestingly, our investigation indicated that simple electrical characteristics such as current density–voltage property are difficult to precisely reflect the minor change in electrical properties due to passivation when the device has the inherently low leakage current. Whereas the EQE was enhanced by 20% and JEQE, peak was largely shifted to a lower current density region at the LED with a size of 15 × 15 μm2. To examine the passivation effects, we carefully analyzed the EQE and JEQE, peak with the ABC recombination model, and established the methodology to investigate the influence of a sidewall in micro-LEDs. As a result, we extracted the surface recombination velocity regarding the surface passivation, showing a nearly 14% reduction with the passivation.

Manganese-doped quantum dots have been explored for a variety of applications, including as display phosphors, light absorbers for photocatalysis and photovoltaics, and in quantum information technologies. The majority of work on Mn-doped quantum dots employs either heavy metal-containing hosts (Cd or Pb) or UV-absorbing hosts (ZnS or ZnSe). Manganese doping in the heavy metal free, visible-light-absorbing, InP quantum dot material is relatively underexplored. In particular, only a handful of studies probe the excited state dynamics in these materials. To build a deeper picture of the photophysics in these materials, the current work employs InP/Mn x Zn 1-x S core/shell quantum dots with varying Mn concentrations. Temperature-dependent and time-resolved photoluminescence spectroscopy is used to explore the forward and reverse energy transfer between the InP excitonic state and the excited Mn state. We find that the InP to Mn energy transfer rate constant is proportional to Mn concentration. Furthermore, we show that an equilibrium exists between these two states that can be well understood with Boltzmann statistics and allows for thermally-activated delayed photoluminescence from the InP exciton (∼4 ms).

In this work, an optimization of the InGaP/GaAs dual-junction (DJ) solar cell performance is presented. Firstly, a design for the DJ solar cell based on the GaAs tunnel diode is provided. Secondly, the used device simulator is calibrated with recent experimental results of an InGaP/GaAs DJ solar cell. After that, the optimization of the DJ solar cell performance is carried out for two different materials of the top window layer, AlGaAs and AlGaInP. For AlGaAs, the optimization is carried out for the following: aluminum (Al) mole fraction, top window thickness, top base thickness, and bottom BSF doping and thickness. The electrical performance parameters of the optimized cell are extracted: JSC=18.23 mA/cm2, VOC=2.33 V, FF=86.42%, and the conversion efficiency (ηc) equals 36.71%. By using AlGaInP as a top cell window, the electrical performance parameters for the optimized cell are JSC=19.84 mA/cm2, VOC=2.32 V, FF=83.9%, and ηc=38.53%. So, AlGaInP is found to be the optimum material for the InGaP/GaAs DJ cell top window layer as it gives 4% higher conversion efficiency under 1 sun of the standard AM1.5G solar spectrum at 300 K in comparison with recent literature results. All optimization steps and simulation results are carried out using the SLVACO TCAD tool.

In recent years, the growing concern over the presence of toxic aquatic pollutants has prompted intensive research into effective and environmentally friendly remediation methods. Photocatalysis using semiconductor quantum dots (QDs) has developed as a promising technology for pollutant degradation. Among various QD materials, indium phosphide (InP) and its hybrid with zinc sulfide (ZnS) have gained considerable attention due to their unique optical and photocatalytic properties. Herein, InP and InP/ZnS QDs were employed for the removal of dyes (crystal violet, and congo red), polyaromatic hydrocarbons (pyrene, naphthalene, and phenanthrene), and pesticides (deltamethrin) in the presence of visible light. The degradation efficiencies of crystal violet (CV) and congo red (CR) were 74.54% and 88.12% with InP, and 84.53% and 91.78% with InP/ZnS, respectively, within 50 min of reaction. The InP/ZnS showed efficient performance for the removal of polyaromatic hydrocarbons (PAHs). For example, the removal percentage for naphthalene, phenanthrene, and pyrene was 99.8%, 99.6%, and 88.97% after the photocatalytic reaction. However, the removal percentage of InP/ZnS for pesticide deltamethrin was 90.2% after 90 min light irradiation. Additionally, advanced characterization techniques including UV–visible spectrophotometer (UV–Vis), photoluminescence (PL), X-ray diffractometer (XRD), energy-dispersive spectrometer (EDS) elemental mapping, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA) were used to analyze the crystal structure, morphology, and purity of the fabricated materials in detail. The particle size results obtained from TEM are in the range of 2.28–4.60 nm. Both materials (InP and InP/ZnS) exhibited a spherical morphology, displaying distinct lattice fringes. XRD results of InP depicted lattice planes (111), (220), and (311) in good agreement with cubic geometry. Furthermore, the addition of dopants was discovered to enhance the thermal stability of the fabricated material. In addition, QDs exhibited efficacy in the breakdown of PAHs. The analysis of their fragmentation suggests that the primary mechanism for PAHs degradation is the phthalic acid pathway.

Environment-friendly indium phosphide (InP)-based quantum dots (QDs) with efficient red-emitting properties are sufficiently needed to satisfy the requirement of burgeoning display and lighting technology. Currently, the syntheses of InP QDs using tris(trimethylsilyl)phosphine as the precursor are highly toxic and expensive. Herein, we successfully introduced gallium (Ga) ions into tris(dimethylamino)phosphine-based red InP cores through thermally-promoted cation exchange, and the obtained Ga-doped InP cores exhibited significantly increased photoluminescence quantum yields (PLQY) of up to 26%. The existence of Ga was directly confirmed by energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, and the functions of Ga were systematically studied. After subsequent coating of Ga-doped InP cores with ZnSeS and ZnS shells, the resulting Ga-InP/ZnSeS/ZnS QDs achieved a high PLQY of 62% with an emission maximum at 640 nm. In contrast, without Ga-doping, the PLQY only attained 36% using the same synthetic approach. This indicated an approximate 1.7-fold increase in PLQY. The enhancement of photoluminescence was related to the Ga 3+ , as it not only passivated surface defects of InP cores but also reduced core-shell interface stress. The Ga-InP/ZnSeS/ZnS QDs exhibited good stability towards heat treatment and ultraviolet (UV) irradiation. Moreover, the red light-emitting diode (LED) based on Ga-InP/ZnSeS/ZnS QDs performed well in a wide injected current range of 2 to 200 mA, with a maximum power efficiency of 0.68 lm/W. This work showcases Ga-doping through cation exchange as a promising strategy for enhancing the efficiency of InP-based red emitters.

In this paper, we present the development of coplanar waveguide to rectangular waveguide (CPW-WG) transition for broadband millimetre wave applications. The traditional approach for interfacing of components in pure electronics is not possible to implement in micorwave photonics at high frequency range due to some limitations like rigidity and increased loss. In order to overcome this problem, transition structures are usually designed within the waveguide model through split block mechanism. The models developed so far are complex with minimum space of interconnects and less stable due to vertical placement of waveguide. The waveguide structure proposed in this paper is placed along horizontal direction due to which stability of structure is increased and has more space for interconnects. The transition model is designed using indium phosphide (InP) to increase the efficiency and reduce the propagation loss at high frequency range. The simulated design can operate over a bandwidth of 14 GHz with a return loss of 10 dB.

Luminescent solar concentrators (LSC) absorb large-area solar radiation and guide down-converted emission to solar cells for electricity production. Quantum dots (QDs) have been widely engineered at device and quantum dot levels for LSCs. Here, we demonstrate cascaded energy transfer and exciton recycling at nanoassembly level for LSCs. The graded structure composed of different sized toxic-heavy-metal-free InP/ZnS core/shell QDs incorporated on copper doped InP QDs, facilitating exciton routing toward narrow band gap QDs at a high nonradiative energy transfer efficiency of 66%. At the final stage of non-radiative energy transfer, the photogenerated holes make ultrafast electronic transitions to copper-induced mid-gap states for radiative recombination in the near-infrared. The exciton recycling facilitates a photoluminescence quantum yield increase of 34% and 61% in comparison with semi-graded and ungraded energy profiles, respectively. Thanks to the suppressed reabsorption and enhanced photoluminescence quantum yield, the graded LSC achieved an optical quantum efficiency of 22.2%. Hence, engineering at nanoassembly level combined with nonradiative energy transfer and exciton funneling offer promise for efficient solar energy harvesting.

Semiconductor devices capable of generating a vortex beam with a specific orbital angular momentum (OAM) order are highly attractive for applications ranging from nanoparticle manipulation, imaging and microscopy to fiber and quantum communications. In this work, an electrically pumped integrated OAM emitter operating at telecom wavelengths is fabricated by monolithically integrating an optical vortex emitter with a distributed feedback laser on the same InGaAsP/InP epitaxial wafer. A single-step dry-etching process is adopted to complete the OAM emitter, equipped with specially designed top gratings. The vortex beam emitted by the integrated device is captured and its OAM mode purity characterized. The integrated OAM emitter eliminates the external laser required by silicon- or silicon-on-insulator-based OAM emitters, thus demonstrating great potential for applications in communication systems and the quantum domain. Orbital-angular-momentum (OAM) beams have great potential for multiplexing signals in optical communication, but creating a compact source is challenging. The authors integrate a chip-scale optical vortex emitter and DFB laser into a single monolithic device for direct electrically pumped production of OAM beams.

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.

A statistics method is proposed to research the quantitative correlation between device performance and structure parameters fluctuation of avalanche photodiode (APD), through theoretical simulation and setting varied structure parameters. The characteristics of InGaAsP/InP APD and InGaAs/InP APD with the same primary structure parameters are discussed, and the quantitative correlation between excess bias fluctuation and structure parameters fluctuation of the two species APDs is concluded. It is revealed that the excess bias of APD is strongly determined by the doping of charge layer, the width of charge layer and multiplication layer, and it is slightly determined by the doping and the width of absorption layer. Moreover, the two species APDs have close response uniformity and technical stability at the same condition of material manufacture and device process.