An AlGaAs-GaAs patterned Ge tunnel-junction cascade concentrator solar cell: Final subcontract report, 15 October 1986--31 October 1987

Technical Report · Thu Sep 01 04:00:00 EDT 1988

OSTI ID:6675206

Timmons, M L

This report describes research performed in several areas of AlGaAs/GaAs cascade technology. Annealing studies of p/sup +/-Ge layers grown on p/sup +/-GaAs substrates indicate that the Ge-GaAs interfaces are adequately stable to interdiffusional mixing if the interface thermal stress is limited to about 700/degree/C for 1 hour. Specific resistivities of intercell ohmic connections (IOC) remain below the goal of 2 /times/ 10/sup -4/ ohm-cm/sup 2/. The thermal stability of the IOC dictates a growth-temperature limit for the AlGaAs top cell significantly lower than conventional organometallic vapor-phase epitaxial practice. Growing high-quality AlGaAs junctions at 700/degree/C or lower caused some difficulty. Minority-carrier-lifetime degradation was studied, but the causes of lifetime reduction remain largely unidentified. Selective epitaxy of the Ge IOC was developed. Slow etching resulted in substantial under-cutting of photolithographic patterns and created problems with reproducibility. The use of MCPMg appears to be suitable for p-type doping in both GaAs and AlGaAs cell growth. Causes of the relatively poor performance of AlGaAs grown at low temperatures merit further research, since this system is important for solar cells. 13 refs., 16 figs., 4 tabs.

• Research Organization: Solar Energy Research Inst., Golden, CO (USA); Research Triangle Inst., Research Triangle Park, NC (USA)
• DOE Contract Number: AC02-83CH10093
• OSTI ID: 6675206
• Report Number(s): SERI/STR-211-3417; ON: DE89000828
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
ALUMINIUM COMPOUNDS
DATA
DEPOSITION
DIRECT ENERGY CONVERTERS
DOCUMENT TYPES
DOPED MATERIALS
ELEMENTS
EQUIPMENT
FILMS
GALLIUM ARSENIDE SOLAR CELLS
GERMANIUM
INFORMATION
MATERIALS
METALS
NUMERICAL DATA
PERFORMANCE
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PROGRESS REPORT
SOLAR CELLS
SOLAR EQUIPMENT
THIN FILMS