0.52 eV Quaternary InGaAsSb Thermophotovoltaic Diode Technology

Abstract

Abstract. Thermophotovoltaic (TPV) diodes fabricated from 0.52eV lattice-matched InGaAsSb alloys are grown by Metal Organic Vapor Phase Epitaxy (MOVPE) on GaSb substrates. 4cm 2 multi-chip diode modules with front-surface spectral filters were tested in a vacuum cavity and attained measured efficiency and power density of 19% and 0.58 W/cm 2 respectively at operating at temperatures of T radiator = 950 °C and T diode = 27 °C. Device modeling and minority carrier lifetime measurements of double heterostructure lifetime specimens indicate that diode conversion efficiency is limited predominantly by interface recombination and photon energy loss to the GaSb substrate and back ohmic contact. Recent improvements to the diode include lattice-matched p-type AlGaAsSb passivating layers with interface recombination velocities less than 100 cm/s and new processing techniques enabling thinned substrates and back surface reflectors. Modeling predictions of these improvements to the diode architecture indicate that conversion efficiencies from 27-30% and ~0.85 W/cm 2 could be attained under the above operating temperatures.

Effect of material parameters on the open-circuit voltage in a GaInAsSb thermophotovoltaic cell

“…The simulated internal spectral responses have been compared with the available experimental data [4], and a good agreement is obtained. The measured V OC for Ga x In 1Àx As 1Ày Sb y TPV cell, reported by Dashiell et al [5] and Wang [4], is comparable with our simulated results for the similar material bandgap and device structure. Table 2 keeping constant.…”

“…One of the best choices is the quaternary GaInAsSb alloys, because they have the advantage of the versatility in obtaining alloys with a large range of bandgaps from 0.296 eV (4.2 lm) to 0.726 eV (1.7 lm) with the lattice matched to commercially-available GaSb wafers [3], which covers the typical wavelength range of TPV cells with low temperature (800-1700°C) radiators. Most of the recent reported GaInAsSb cells are in the range of 0.5-0.55 eV [3,4], the optimal radiator temperature, when considering 95-97% reflection of all below-bandgap photons is 950°C [5]. 0.53 eV GaInAsSbbased TPV systems have shown more than 19% radiant heat conversion efficiency using refractive spectral control in a TPV system with radiator and cells temperature of 950°C and 27°C, respectively [6].…”

Quaternary InGaAsSb Thermophotovoltaic Diodes

“…Both systems utilized spectral control filters mounted on the front surface of the diode in order to recuperate below bandgap radiation [5], [6]. Quaternary InGaAsSb alloys were investigated because they can be grown lattice matched to GaSb substrates for bandgaps as low as 0.5 eV [7]- [11]; to date, however, the material underperforms compared to ternary InGaAs TPV diodes. This paper summarizes the theory used to predict the practical TPV thermal-to-electric energy conversion efficiency for heat transferred radiatively from a hot-side radiator to a cold-side diode module.…”

Thermophotovoltaic Spectral Control

“…Equation 8 is based on a correlation from Wanlass [6], scaled to be consistent with PC-1D analysis of the projected performance (based on engineering limits) of 0.52 eV InGaAsSb TPV diodes [7] and 0.60 eV InGaAs diodes. The following assumptions were used in the PC-1D analyses:…”