Study of thermal strain relaxation in GaAs grown on Ge/Si substrates

A detailed analysis of the thermal strain relaxation in GaAs/Ge/Si structures by means of crack formation is presented. The study was performed through optical microscopy and photoluminescence measurements. The as grown epilayers were found to be in a metastable state with respect to crack formation. Repeated thermal cycling increased the crack density up to an asymptotic limit. The thermal strain is not fully relaxed even near to the asymptotic crack density.