New Approaches for High Efficiency Solar Cells: Final Report

This report summarizes the activities carried out in this subcontract. These activities cover growing GaAs, AlGaAs, and InGaP by atomic- layer epitaxy (ALE) at fairly low growth temperatures; using ALE to achieve high levels of doping both n-type and p-type required for tunnel junctions in the cascade solar cell structures; and studying the properties of AlGaAs/InGaP and AlGaAs/GaAs tunneljunctions in stacked solar cell structures. The effect of these tunnel junctions on the performance of stacked solar cells was studied at different temperatures and different solar fluences. Researchers also studied the effect of different types of back-surface fields, both p/n and n/p GaInP solar cell structures, and their potential for window-layer applications. Parts of these activities werecarried out in close cooperation with Dr. Mike Timmons of the Research Triangle Institute.