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U.S. Department of Energy
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Development of high-efficiency stacked multiple-bandgap solar cells. Interim technical report 1 August 78-1 October 79

Technical Report ·
OSTI ID:5779855

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.

Research Organization:
Rockwell International Corp., Anaheim, CA (USA). Electronics Research Div.
OSTI ID:
5779855
Report Number(s):
AD-A-096764/6
Country of Publication:
United States
Language:
English