Development of High-Efficiency Stacked Multiple-Bandgap Solar Cells.
Abstract
The first 14-month program of a twenty-four month experimental investigation backed by analytical modeling has been conducted to develop technologies required for fabricating stacked multiple bandgap solar cell (SMBSC) assemblies having AMO 1-sun efficiencies of 25% or greater at 25 C. Investigations were undertaken with the following four SMBSC materials systems: (1) two-cell GaAs-Ge structure, made by metalorganic chemical vapor deposition (MO-CVD), conventional CVD, and molecular-beam epitaxy (MBE) methods; (2) two-cell GaAs-InGaAs structure, made by liquid-phase epitaxy (LPE) techniques; (3) three-cell GaAlAs-GaAs-GaAsSb structure, made by MO-CVD and MBE methods; and (4) three-cell GaAlAs-GaAs-InGaAsP structure, made by LPE and MBE methods. Each of these systems involves the GaAlAs-GaAs materials combination as the basic building block. Near the end of the program a change in emphasis was introduced to limit the investigations to GaAlAs-GaAs and GaAs-Ge two-cell structures and the three-cell GaAlAs-GaAs-Ge structure that might also result. Principal emphasis was then placed on the MO-CVD technique, supplemented by MBE, LPE, or other deposition and/or processing techniques where appropriate. The principal achievement was with the GaAlAs-GaAs system, in which a two-cell SMBSC that exhibited voltage addition (Voc approx = 2.1 V) under illumination was successfully fabricated. The two individual cells and the connecting tunnel junction were grown entirely by MO-CVD techniques in this structure. Similar structures made by a combination of MO-CVD and MBE techniques also appeared quite promising.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1980
- Accession Number
- ADA096764
Entities
People
- J. S. Harris
- P. D. Dapkus
- R. P. Ruth
- Russell D. Dupuis
- S. W. Zehr