Characterizing the Layer Properties of AlGaAs/GaAs Heteroface Solar Cell Structures by Specular Spectral Reflectance

摘要

A cheap and non-destructive method for characterizing wafers priorto, during, and after processing is presented. This method is basedon optical reflectance measurements. Its application to AlGaAs/GaAsheteroface solar cell structures allows the determination of thethickness of both the cap and window layers, the aluminum composition(even if it is graded) of the window layer and both the thickness andcomposition of surface oxide (if any). The feasibility of theprocedure and method here presented is demonstrated by applying it totwo kinds of structures grown by MOCVD (metal organic chemical vapordeposition) and LPE (liquid phase epitaxy). The results obtained arevalidated experimen- tally by SIMS and Raman. Finally, the influenceof several calculation param- eters on the final result is analyzed.