Strained and strain-balanced quantum well devices for high-efficiency tandem solar cells

The state of GaAs/InGaAs quantum well solar cell research is reviewed. The effect of strain upon the GaAs/InGaAs cells is discussed and the limits to a strained GaAs/InGaAs cell established. The strain-balance approach is sug gested as a means of overcoming the limits inherent to the strained approac h and the principle is demonstrated in two differing device configurations. The strain-balance devices show enhanced efficiencies over their strained counterparts and in one case, comparable efficiency to a good GaAs control cell. The application of these cells to tandem structures is discussed, ind icating the potential for a substantial efficiency enhancement. (C) 2001 El sevier Science B.V. All rights reserved.