Ultrathin GaAs solar cells using germanium substrates

The authors present their approach of etch thinning to produce ultrathin (less than 6 μm GaAs thickness) devices utilizing cheaper Ge substrates to attack the problems of high cost and mass. The use of a double heterostructure GaAs cell design and a total loss etch process to produce devices of only 6 μm GaAs thickness is discussed. The benefits of this process in comparison with alternative ultrathin GaAs cell techniques are outlined. The mass specific power of this class of device using a 100 μm coverglass can exceed 670 W/kg at the connector integrated cell level, compared with less than 330 W/kg for 100 μm silicon cells