Plastic Deformation in Epitaxial Ge Layers Grown on Single Crystal Semi-Insulating GaAs

The compatibility of Ge and , in terms of their temperature dependent mechanical properties, is described in this paper. Examination at room temperature of epitaxial Ge layers grown on wafers of single crystal, semi‐insulating , at substrate temperatures of 700°C by pyrolytic dissociation of , reveals evidence of plastic deformation immediately following the epitaxial deposition process. Plastic deformation is observed in epitaxial Ge layers grown at 350°C, by disproportionation of , only after a subsequent annealing cycle to at least 500°C. The low substrate temperature Ge films, however, show elastic bending of thin substrates after deposition and cooling to room temperature. Based on these observations, it is possible to estimate the differential thermal expansion coefficient between Ge and , and to use this result to estimate the critical shear stress for plastic deformation under low strain rate conditions . Interface dislocations are not observed.