Temperature dependence of direct transition energies in β- epitaxial films on Si(111) substrate

Temperature dependence of direct transition energies (Eg) was investigated in β- epitaxial films on Si(111) substrate. The lattice volume of the epitaxial films was reduced as the annealing temperature (Ta) increased. In photoreflectance measurements, the samples annealed at higher Ta showed a larger temperature dependence of Eg. These results revealed that the temperature dependence of Eg depended on the lattice deformation by the thermal annealing. The fact supports the band gap modifications by the lattice deformation.