Indium Gallium Arsenide Antimonide Research Articles

Revisiting tantalum based nanostructures for efficient harvesting of solar radiation in STPV systems

The Shockley-Queisser limit places an upper bound on the efficiency of conventional semiconductor photovoltaic (PV) devices. A solar thermophotovoltaic (STPV) system (consisting of an ultra-broadband absorber, spectrally selective emitter, and low bandgap PV cell) can provide an efficient alternative to overcome this theoretical limit over efficiency. However, the stringent design requirements of absorber and emitter (like thermal stability and angular and polarization insensitivity) require a careful selection of appropriate material, meticulous engineering, and optimization of nanostructures to ensure high performance of the overall STPV system. In this work, we present a Tantalum (Ta) based nanostructured ultra-broadband absorber and thermal emitter for an SPTV system. Tantalum, being a refractory metal and having high thermal stability due to its high melting point, is an ideal candidate for the design of both absorber and the spectrally selective emitter. Both the presented absorber and emitter employ cross-shaped Ta nanostructures (as a top layer) due to their high spectral selectivity and polarization insensitivity. Our numerical investigations (well supported by a description of underlying mechanism) reveal that our carefully designed and optimized devices (both the absorber and emitter) outperform previously reported ones. The proposed absorber exhibits high absorptance for blackbody radiation at 5778 K and air mass (AM) 1.5, while the proposed emitter, due to its high spectral selectivity, outperforms previously reported demonstrations in terms of PV cell efficiency (41.8%) for Indium Gallium Arsenide Antimonide (InGaAsSb with 0.55 eV bandgap). Moreover, it is shown that by simple manipulation of length, we can steer the maxima of the emittance curve for different wavelengths as well, which is helpful in designing the emitter for other PV cells with different bandgaps. Furthermore, it is shown that dielectric coatings can be employed on designs to achieve thermal stability without compromising efficiency. • This work presents a Tantalum (Ta) based ultra-broadband absorber and thermal emitter for an SPTV system. • Tantalum has a high melting point, making it an ideal candidate for absorber design and the spectrally selective emitter. • The absorber and emitter achieve high spectral selectivity outperforming previously reported STPV systems. • The proposed absorber gives high absorptance while the proposed emitter achieves 41.8% efficiency for InGaAsSb (0.55 eV). • Dielectric coatings can be employed for thermal stability, and simple manipulation of length can tune the emittance curve.

Radioisotope Thermophotovoltaic Generator Design Methods and Performance Estimates for Space Missions

This work provides the design methodology of a radioisotope thermophotovoltaic system (RTPV) using spectral control for space missions. The focus is on the feasibility of a practical system by using two-dimensional micropatterned photonic crystal emitters, selecting the proper thermophotovoltaic cell and insulation material to exclude material incompatibilities, to optimize the system efficiency by impedance matching and to design a radiator with minimum mass. In the last section, a design example is presented based on the tested indium gallium arsenide antimonide (InGaAsSb) cells. It is shown computationally that, in using the experimentally tested InGaAsSb cells, the RTPV generator is expected to reach an efficiency of 8.6% and a specific power of with advanced radiators. Using the more efficient InGaAs cells, the system can expect to triple the figure of merits of the radioisotope thermoelectric generator, promising to reach and , respectively. With a high performance device, the results of this work can lead to a functional prototype for further research focusing on manufacturability and reliability.

Circularly Polarized Cross-Tapered Bowtie Antenna for IR Polarimetry

We propose a novel cross bowtie antenna using phase-shift lines to realize circular polarization (CP) in the infrared (IR) spectrum. The CP antenna consists of a vertical, a horizontal antenna, and two elliptical loops connecting adjacent tips of the antennas to create a 90° phase shift. The phase-shift lines are conceived to realize a single terminal of the antenna where a detecting material can be mounted and enable the detecting material to fully utilize the field enhancement from the antenna. In full-wave simulations, a nanometer-scale low-bandgap semiconductor, i.e., indium gallium arsenide antimonide (InGaAsSb) capable of detecting IR wave is loaded at the antenna terminal and the antenna structure is designed to achieve CP absorption at 180 THz. The antenna includes a transmission line-based impedance matching structure to compensate for the reactance of the InGaAsSb semiconductor load. To verify the CP detection of the antenna near 180 THz, we numerically show a higher field enhancement value and absorption rate in the antenna terminal in a specific CP case when the antenna is illuminated with incident waves with various polarization states. Also, we design 2 × 1 and 2 × 2 antenna arrays using the CP antennas connected with metallic traces and show that the CP absorption at 180 THz is maintained. Finally, an illustration of a focal plane array based on the proposed CP cross bowtie antennas coupled with the InGaAsSb for a full Stokes polarimeter is presented.

Indium gallium arsenide antimonide photodetector grown by liquid phase epitaxy: Electrical characterization and optical response

Current–voltage (I–V) and R0A curves and spectral response as a function of bias voltage and temperature of p–n indium gallium arsenide antimonide (In0.14Ga0.86As0.13Sb0.87)/n-GaSb photodiodes are presented. InGaAsSb quaternary alloys with a bandgap energy of about 653meV were grown using the liquid phase epitaxy technique on top of (100) GaSb substrates. Device structure was fabricated using a process that includes passivation with sodium sulfide, thermal annealing and metallizations. The diode architecture was a back-illuminated (B-I) structure with a ring-shaped metallic contact in the GaSb substrate face. Photodiode spectral response showed good performance in the entire temperature range between 20K and 300K.

Bowtie nanoantenna integrated with indium gallium arsenide antimonide for uncooled infrared detector with enhanced sensitivity

A novel high-impedance nanoantenna with an embedded matching network is implemented to realize a highly sensitive infrared detector. A bowtie antenna is operated at its antiparallel resonance and loaded with a small low-bandgap (E(g)=0.52 eV) indium gallium arsenide antimonide (InGaAsSb) p-n junction. The structure is optimized for maximum power transfer and significant field enhancement at its terminals for a desired frequency band where the maximum quantum efficiency of InGaAsSb is observed. The sensitivity improvement of the proposed detector is evaluated against the traditional bulk detector and it is shown that the detectivity is improved by the field enhancement factor, which is approximately 20 for the case considered here.

Design optimization of bowtie nanoantenna for high-efficiency thermophotovoltaics

A novel matching technique and the field enhancement at the terminals of a bowtie nanoantenna are utilized to develop compact, highly efficient, and flexible thermophotovoltaic (TPV) cells. The bowtie antenna is designed for maximum power transfer to a near infrared band (1 μm to 2.2 μm) of a TPV cell using Indium Gallium Arsenide Antimonide (InGaAsSb). A nano-meter size block of InGaAsSb with a low bandgap energy of 0.52 eV is mounted at the terminals of the antenna. Such a load presents a frequency dependent impedance with a high resistance and capacitance at the desired frequency (180 THz). For maximum power transfer, a high impedance bowtie antenna operating at the anti-resonance mode in conjunction with an inductive stub is realized. The plasmonic behavior of the metal that tends to reduce the antenna size is partially compensated by the extra length needed to achieve the anti-resonance condition. At the desired band, the proposed nanoantenna loaded with InGaAsSb block shows an electric field intensity at the antenna terminals, which is approximately 23.5 times higher than the incident electric field intensity. This feature allows for development of efficient TPV cell and sensitive IR detectors. The infinite array of the bowtie antennas backed by a metallic reflector located at a quarter-wave behind the array is shown to absorb ∼95% of the incident power, which is more than 50% higher than the bulk InGaAsSb TPV cell. A novel configuration of the bowtie nanoantenna array is also presented that allows for collection of DC currents through an almost arbitrary parallel or series configuration of TPV cells without adversely affecting the IR performance of the individual antennas. In this scheme, elements can be arranged to be polarization dependent or independent.