Temperature dependence of the Raman shift in GaAs conformal layers grown by hydride vapor phase epitaxy

Raman spectra between room temperature and 350 degreesC were measured in GaAs layers grown by hydride vapor phase epitaxy on Si substrates using the selective conformal growth method. The contributions of the thermal expansion, anharmonic phonon decay, and strain are considered in order to analyze the Raman data. The tensile strain in the conventional GaAs/Si seed and in the conformal GaAs layers was determined from the Raman spectra. It is shown that the thin SiO2 layer between the GaAs and the Si substrate is a compliant layer that plays an important role in the reduction of the dislocation density in the conformal layers. The tensile strain in conformal layers was higher than in the conventional GaAs/Si layers, in which strain is relieved by the high density of dislocations. (C) 2002 American Institute of Physics.