Growth and properties of InGaAs/FeAl/InAlAs/InP heterostructures for buried reflector/interconnect applications in InGaAs thermophotovoltaic devices
- Ohio State Univ., Columbus, OH (United States). Dept. of Electrical Engineering
- Bettis Atomic Power Lab., West Mifflin, PA (United States)
Thermophotovoltaic cells consisting of InGaAs active layers are of extreme promise for high efficiency, low bandgap TPV conversion. In the monolithic interconnected module configuration, the presence of the InGaAs lateral conduction layer (LCL) necessary for the series connection between TPV cells results in undesirable free carrier absorption, causing a tradeoff between series resistance and optical absorption losses in the infrared. A potential alternative is to replace the LCL with an epitaxial metal layer that would provide a low-resistance interconnect while not suffering from free carrier absorption. The internal metal layer would also serve as an efficient, panchromatic back surface reflector, providing the additional advantage of increased effective optical thickness of the InGaAs cell. In this paper, the authors present the first results on the growth and development of buried epitaxial metal layers for TPV applications. High quality, single crystal, epitaxial Fe{sub x}Al{sub 1{minus}x} layers were grown on InAlAs/InP substrates, having compositions in the range x = 0.40--0.80. Epitaxial metal layers up to 1,000 {angstrom} in thickness were achieved, with excellent uniformity over large areas and atomically smooth surfaces. X-ray diffraction studies indicate that all FeAl layers are strained with respect to the substrate, for the entire composition range studied and for all thicknesses. The FeAl layers exhibit excellent resistance characteristics, with resistivities from 60 {micro}ohm-cm to 100 {micro}ohm-cm, indicating that interface scattering has a negligible effect on lateral conductivity. Reflectance measurements show that the FeAl thickness must be at least 1,000 {angstrom} to achieve > 90% reflection in the infrared.
- Research Organization:
- Bettis Atomic Power Lab., West Mifflin, PA (United States)
- Sponsoring Organization:
- USDOE Assistant Secretary for Nuclear Energy, Washington, DC (United States)
- DOE Contract Number:
- AC11-93PN38195
- OSTI ID:
- 296648
- Report Number(s):
- WAPD-T-3221; CONF-981055-; ON: DE99000486; TRN: AHC29903%%46
- Resource Relation:
- Conference: 4. National Renewable Energy Laboratory (NREL) conference on thermophotovoltaic generation of electricity, Denver, CO (United States), 11-14 Oct 1998; Other Information: PBD: [1998]
- Country of Publication:
- United States
- Language:
- English
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