Title :
GaAs/Ge tandem-cell space concentrator development
Author :
Wojtczuk, Steven J. ; Tobin, Stephen P. ; Keavney, Christopher J. ; Bajgar, Clara ; Sanfacon, Michael M. ; Geoffroy, Leo M. ; Dixon, Todd M. ; Vernon, Stanley M. ; Scofield, James D. ; Ruby, Douglas S.
Author_Institution :
Spire Corp., Bedford, MA, USA
fDate :
2/1/1990 12:00:00 AM
Abstract :
GaAs/Ge monolithic tandem two-junction concentrators are being developed by optimizing separate one-junction GaAs and Ge cells that simulate the GaAs top cell and Ge bottom cell of the tandem. Separation allows easier analysis of the tandem´s top and bottom cells than if these two junctions were in series. The best GaAs top cell has an independently measured AM1.5D efficiency of 28.7% at 200 suns and 25°C (24.5% AM0 at 170 suns), a record for a monolithic cell without a prismatic cover. The Ge bottom cells have a GaAs optical filter (but no GaAs junction) to replicate the spectrum that the Ge cell sees when incorporated into a tandem. The best Ge-under-GaAs bottom cell efficiency is 4.6% AM0 at 103 suns. Evidence that the 900-1800-nm response seen from the Ge bottom cell is due to a p-n junction in the Ge and not a GaAs/Ge heterojunction is presented
Keywords :
III-V semiconductors; elemental semiconductors; gallium arsenide; germanium; solar cells; solar energy concentrators; space vehicle power plants; 4.6 to 28.7 percent; 900 to 1800 nm; AlGaAs-GaAs-Ge; GaAs top cell; GaAs/Ge tandem-cell; Ge bottom cell; monolithic solar cells; optical filter; semiconductors; space concentrator; Gallium arsenide; Low earth orbit satellites; Optical filters; P-n junctions; Photonic band gap; Solar power generation; Space technology; Substrates; Sun; Test equipment;
Journal_Title :
Electron Devices, IEEE Transactions on
