Pressure-induced resonant Raman scattering in Ge/Si islands

Abstract

Self-assembled Ge islands grown by solid-source molecular-beam epitaxy were investigated by resonant Raman scattering under hydrostatic pressure at room temperature. We utilize the effect of pressure to tune the electronic transition through laser excitation energies in the Ge islands. The pressure coefficient of this resonating electronic transition thus obtained is ∼2.7±0.5 meV/kbar, which is significantly smaller than the pressure shift of the El transition in bulk Ge. This is attributed to the fact that the Ge islands are strongly constrained by the surrounding Si lattice, leading to a smaller deformation as compared to the bulk Ge, when subjected to the same pressure.