Temperature dependence of residual stress in epitaxial GaAs/Si(100) films determined from photoreflectance spectroscopy data

In the temperature range T = 10-300 K, photoreflectance spectroscopy was used to study the temperature dependence of residual stress in epitaxial n-GaAs films (1-5 mu m thick, electron concentration of 10(16)-10(17) cm(-3)) grown on Si(100) substrates. A qualitative analysis showed that the photoreflectance spectra measured in the energy region of the E-0 transition in GaAs had two components. They consisted of the electromodulation component caused by the valence subband \3/2; +/-1/2]-conduction band transition and the low-energy excitonic component. The magnitude of stress was determined from the value of the strain-induced energy shift of the fundamental transition from the subband \3/2; +/-1/2] with respect to the band gap of the unstressed material E-0(T)-E-0(\3/2; +/-1/2])(T). The increase in the energy shift E-0-E-0(\3/2; +/-1/2]) from 22 +/- 3 meV at 296 K to 29 +/- 3 meV at 10 K, which was found in the experiments, gives evidence of an increase in biaxial stress with decreasing temperature. (C) 2000 MAIK Nauka/Interperiodica.