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This paper presents a theoretical analysis of an nBp infrared barrier detector's performance intended to operate at a room temperature (300 K) based on AIIIBV materials—In1-xGaxAsySb1−y quaternary compound—lattice-matched to the GaSb substrate with a p-n heterojunction ternary Al1−xGaxSb barrier. Numerical simulations were performed using a commercial Crosslight Software—package APSYS. The band structure of the nBp detector and the electric field distribution for the p-n heterojunction with and without a potential barrier were determined. The influence of the barrier-doping level on the detector parameters was analyzed. It was shown that Shockley-Read-Hall (SRH) recombination plays a decisive role in carrier transport for lifetimes shorter than 100 ns. The influence of the absorber/barrier thickness on the detector's dark current density and photocurrent was investigated. It was shown that valence band offset does not influence the device's performance. The quantum efficiency reaches its maximum value for an absorber's thickness of ~3 μm. The performed simulations confirmed the possibility of the detector's fabrication exhibiting high performance at room temperature based on quaternary compounds of AIIIBV materials for the short wavelength infrared range. [ABSTRACT FROM AUTHOR]

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High-voltage gradual p0–i–n0 junctions of AlxGa1 –xAs1 –ySby with x ~ 0.24 and y ~ 0.05 in the i‑region were studied using capacitance-voltage characteristics method and transient spectroscopy of deep levels. It has been established that the effective recombination trap in them is the DX-center of the Si donor impurity, with a thermal activation energy Et = 414 meV, a capture cross section σn = 1.04 × 10–14 cm2, and a concentration Nd = 2.4 × 1015 cm–3. In the heterostructures studied, there were no deep levels associated with dislocations. [ABSTRACT FROM AUTHOR]

Thermophotovoltaic conversion using heat to generate electricity in photovoltaic cells based on the detraction of thermal radiation suffers from many engineering challenges. The focus of this paper is to study the nanostructure of AlGaAsSb for thermophotovoltaic energy conversion using lattice-matched heterostructures of GaSb-based materials in order to overcome the current challenges. The XAFS spectroscopy technique was used to analyze electronic structures and optical properties of GaSb, (Al, In) GaSbAs. The XAFS spectroscopy analysis showed a powerful decay at peak intensity that reveals to be related to a loss in Sb amount and light As atoms replaced in Sb atoms by 25%. Moreover, it was found that Al/In doped samples have highly symmetric data features (same atomic species substitution). The narrow direct bandgap energy, Eg of Al0.125Ga0.875Sb0.75As0.25 material raised (0.4–0.6 eV) compared to conventional photovoltaic cell bandgap energy (which is generally less than 0.4 eV) with weak absorption coefficients. The thermoelectric properties of AlGaAsSb computed via Botlztrap code showed that the electrons made up the majority of the charge carriers in AlGaAsSb. This nanostructure material exhibited a higher and acceptable figure of merit and demonstrated a promising thermoelectric material for solar thermophotovoltaic applications. [ABSTRACT FROM AUTHOR]

We provide an overview of our progress on the development of linear mode avalanche photodiodes (LmAPDs) on InP substrates using antimony (Sb)-based multipliers for short-wavelength infrared (SWIR) spectral region. We identify the key figures of merit of LmAPDs to provide higher sensitivity and speed for applications like light detection and ranging (LiDAR) and remote sensing. We discuss the design of separate absorption, charge, and multiplication (SACM) APDs that are used for narrow gap absorption. We summarize our results on the impact ionization, multiplication gain, dark current, and excess noise of AlGaAsSb and AlInAsSb multipliers lattice-matched to InP substrates. Finally, we identify the key technical challenges associated with the development of SACM APDs on InP substrates. [ABSTRACT FROM AUTHOR]

Digital alloy and random alloy Al0.85Ga0.15As0.56 Sb0.44 avalanche photodiodes (APDs) exhibit low excess noise, comparable to Si APDs. Consequently, this material is a promising multiplication layer candidate for separate absorption, charge, and multiplication structure APDs with high gain-bandwidth product. Characterization of the impact ionization coefficients of electrons (α) and holes (β) plays an important role in the simulation of avalanche photodiodes. The multiplication gain curves of eight p+-i-n+ and n+-i-p+ APDs covering a wide range of avalanche widths have been used to determine the electric field dependence of the impact ionization coefficients of Al0.85Ga0.15As0.56Sb0.44. A large impact ionization coefficient ratio between that of electrons to holes was seen across a wide electric field range. Simulations of the avalanche multiplication in these structures using a random path length (RPL) model gave good agreement with experimental results over almost three orders of magnitude, and a mixed injection method was employed to verify the extracted impact ionization coefficients. Interestingly, no difference in the impact ionization coefficients was seen between digital alloy and random alloy Al0.85Ga0.15As0.56Sb0.44. This knowledge of impact ionization coefficients is beneficial for the future utilization of the AlxGa1-xAsySb1-y material system. [ABSTRACT FROM AUTHOR]

Avalanche photodiodes (APDs) made with the material AlGaAsSb (lattice-matched to InP) exhibit very low excess noise characteristics. We demonstrate a Separate Absorption and Multiplication APD (SAM-APD) incorporating a GaAs0.52Sb0.48 (GaAsSb) absorption region and an Al0.85Ga0.15As0.56Sb0.44 (AlGaAsSb) avalanche region. Our GaAsSb/AlGaAsSb SAM-APD exhibits a cut-off wavelength of 1.70 μm at room temperature and a responsivity of 0.39 A/W at 1.55 μm wavelength (with no antireflection coating). Temperature dependence of the breakdown voltage was obtained from avalanche gain data from multiple devices operated at 77 to 295 K. This produced a temperature coefficient of breakdown voltage of 4.31±0.33 mV/K, a factor of 10 and 5 smaller than values for comparable InP and InAlAs SAM-APDs. The very small temperature coefficient of this work is consistent with the extremely weak temperature dependence of avalanche breakdown previously observed in AlGaAsSb diodes. [ABSTRACT FROM AUTHOR]

Avalanche breakdown characteristics are essential for designing avalanche photodiodes. In this letter, we investigated the effects of adding Ga to Al1–xGaxAs0.56Sb0.44 quaternary alloys. Using p-i-n diodes with a 100-nm i—region and alloy composition ranging from $x=0$ to 0.15, we found that the bandgap energy of Al1–xGaxAs0.56Sb0.44 reduces from 1.64 to 1.56 eV. The corresponding avalanche breakdown voltage decreases from 13.02 to 12.05 V, giving a reduction of 64.7 mV for every percent addition of Ga. The surface leakage current was also found to be significantly lower in the diodes with $x=0.10$ and 0.15 suggesting that Ga can be added to reduce the surface leakage current while still preserving the lattice match to InP substrate. The data from this letter can be downloaded freely. [ABSTRACT FROM PUBLISHER]

The increasing number of subcells in multi-junction structures imposes the use of narrow bandgaps for a full harvesting of the solar spectrum. In this context, gallium antimonide (GaSb) and its lattice-matched alloys offer a great potential. To date, GaSb-based multi-junction solar cells exhibit experimental results below theoretical expectations, due to a limiting GaSb subcell. In this paper, a new design of GaSb cells comprising an Al 0.50 Ga 0.50 As 0.04 Sb 0.96 window layer is studied. With this design, an excellent conversion efficiency of 7.2% is achieved under 1 sun (AM1.5G) illumination. This performance is attributed to a significant improvement in short-circuit current. [ABSTRACT FROM AUTHOR]