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Title: An inverted AlGaAs/GaAs patterned-Ge tunnel junction cascade concentrator solar cell

This report describes work to develop inverted-grown Al[sub 0.34]Ga[sub 0.66]As/GaAs cascades. Several significant developments are reported on as follows: (1) The AM1.5 1-sun total-area efficiency of the top Al[sub 0.34]Ga[sub 0.66]As cell for the cascade was improved from 11.3% to 13.2% (NREL measurement [total-area]). (2) The cycled'' organometallic vapor phase epitaxy growth (OMVPE) was studied in detail utilizing a combination of characterization techniques including Hall-data, photoluminescence, and secondary ion mass spectroscopy. (3) A technique called eutectic-metal-bonding (EMB) was developed by strain-free mounting of thin GaAs-AlGaAs films (based on lattice-matched growth on Ge substrates and selective plasma etching of Ge substrates) onto Si carrier substrates. Minority-carrier lifetime in an EMB GaAs double-heterostructure was measured as high as 103 nsec, the highest lifetime report for a freestanding GaAs thin film. (4) A thin-film, inverted-grown GaAs cell with a 1-sun AM1.5 active-area efficiency of 20.3% was obtained. This cell was eutectic-metal-bonded onto Si. (5) A thin-film inverted-grown, Al[sub 0.34]Ga[sub 0.66]As/GaAs cascade with AM1.5 efficiency of 19.9% and 21% at 1-sun and 7-suns, respectively, was obtained. This represents an important milestone in the development of an AlGaAs/GaAs cascade by OMVPE utilizing a tunnel interconnect and demonstrates a proof-of-concept for the inverted-growth approach.
Authors:
 [1]
  1. (Research Triangle Inst., Research Triangle Park, NC (United States))
Publication Date:
OSTI Identifier:
6744462
Report Number(s):
NREL/TP-411-5289
ON: DE93000073
DOE Contract Number:
AC02-83CH10093
Resource Type:
Technical Report
Research Org:
National Renewable Energy Lab., Golden, CO (United States); Research Triangle Inst., Research Triangle Park, NC (United States)
Sponsoring Org:
DOE; USDOE, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; GALLIUM ARSENIDE SOLAR CELLS; FABRICATION; BONDING; CARRIER LIFETIME; CHARGE CARRIERS; EPITAXY; GALLIUM ARSENIDES; PHOTOVOLTAIC CONVERSION; PROGRESS REPORT; SEMICONDUCTOR JUNCTIONS; SILICON; SOLAR CONCENTRATORS; SUBSTRATES; THIN FILMS; ARSENIC COMPOUNDS; ARSENIDES; CONVERSION; DIRECT ENERGY CONVERSION; DIRECT ENERGY CONVERTERS; DOCUMENT TYPES; ELEMENTS; ENERGY CONVERSION; EQUIPMENT; FILMS; GALLIUM COMPOUNDS; JOINING; JUNCTIONS; LIFETIME; PHOTOELECTRIC CELLS; PHOTOVOLTAIC CELLS; PNICTIDES; SEMIMETALS; SOLAR CELLS; SOLAR EQUIPMENT 140501* -- Solar Energy Conversion-- Photovoltaic Conversion; 360601 -- Other Materials-- Preparation & Manufacture