Electronic structure and optical characteristics of the hybrid GaN/por-Si heterostructures

GaN/Si(111) heterostructures grown by plasma-assisted molecular beam epitaxy on routine Si(111) substrates and compliant por-Si/Si(111) substrates without using AlN buffer layer was studied by using various structural and spectroscopy methods of analysis. XPS study revealed that the layer is grown on the compliant substrate of por-Si being closer to the stoichiometric composition. The shift of the A1(LO) mode in the Raman spectrum confirms the lattice-matched growth type on the compliant substrate in comparison with the routine c-Si substrate. The experimentally determined value of the optical bandgap width for the epitaxial GaN layer grown on por-Si substrate exceeds that of the layer grown on single-crystalline silicon c-Si by 0.1 eV (paper)