Raman Scattering and Photoluminescence Characterization of Stress in GaAs on Si Substrate Grown with an Intermediate Layer of Ge or CaF sub 2

For the reliable performance of the GaAs opto-electronic devices on Si, a significant reduction in the amount of residual stress, which develops due to the lattice mismatch and thermal mismatch between GaAs and Si, is needed. The reduction in the wafer warpage and the internal stress in the films can be achieved by (a) growing at low temperature, (b) pre-stressing Si substrate, (c) back-coating Si substrate with materials of higher (than Si) thermal expansion coefficient, and (d) using buffer layers with good thermal and lattice match to GaAs.