Plasmachemical and Wet Etching in the Postgrowth Technology of Solar Cells Based on the GaInP/GaInAs/Ge Heterostructure

Abstract

Abstract—Studies have been carried out and a technology has been developed for the formation of a separating mesa structure in fabrication of multi-junction solar cells based on the GaInP/GaInAs/Ge heterostructure. Methods for etching of the heterostructure layers have been studied: wet chemical etching in compositions based on HBr, K2Cr2O7, and H2O and the plasmachemical etching in a flow of the BCl3 working gas. A comparative analysis of the etching methods was made. Protective masks based on a photoresist layer and TiOx/SiO2 were developed. Multi-junction solar cells with low leakage current (less than 10–7 A at a voltage of 0.5–1 V) were fabricated.