Al{sub x}Ga{sub 1{minus}x}Sb window layers for InGaAsSb/GaSb thermophotovoltaic cells
- Materials Science and Engineering, University of Delaware, Newark, Delaware 19716-2000 (United States)
We report results of a comparative study of AlSb-based window layers for InGaAsSb/GaSb TPV cells made by liquid-phase epitaxy (LPE). Previous work has shown that an AlGaAsSb window layer significantly improves the performance of InGaAsSb/GaSb TPV cells. As expected, the window layer enhances short-wavelength spectral response and increases the open-circuit voltage by reducing the reverse-saturation current of the diode. We present results for a simpler alternative window layer based on the ternary AlGaSb alloy. We fabricated, characterized, and compared InGaAsAsSb TPV of three types: 1. with an AlGaAsSb window layer, 2. with an AlAsSb window layer, and 3. with no window layer. Both {ital p}-on-{ital n} ({ital p}-type InGaAsSb emitter; {ital n}-type InGaAsSb base) and {ital n}-on-{ital p} ({ital n}-type InGaAsSb emitter; {ital p}-type InGaAsSb base) homojunction cell configurations were investigated. The InGaAsSb layers have a {approximately}0.55-ev bandgap and are lattice-matched to a GaSb substrate. As anticipated, both AlGaSb and AlGaAsSb passivated TPV cells were superior to cells without a window layer. The AlGaAsSb/InGaAsSb window/emitter interface is closely lattice matched and would be expected to provide better surface passivation than AlGaSb/InGaAsSb window/emitter interface which has a 0.6{percent} lattice mismatch. On the contrary, our experimental results showed that, based on a comparison of spectral response, AlGaSb window layers were somewhat more effective than AlGaAsSb in passivating the front surface of InGaAsSb diodes. These results demonstrate the viability of a simpler ternary AlGaSb alloy as an alternative to the quaternary AlGaAsSb alloy as a window layer material. {copyright} {ital 1999 American Institute of Physics.}
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG02-97ER86057
- OSTI ID:
- 700929
- Report Number(s):
- CONF-981055--
- Journal Information:
- AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 460; ISSN 0094-243X; ISSN APCPCS
- Country of Publication:
- United States
- Language:
- English
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