Structural and Optical Properties of Ge_(1-x)Sn_x Alloys Grown on GaAs (001) by R. F. Magnetron Sputtering

摘要

Ge_(1-x)Sn_x alloys were grown on GaAs (001) substrates in a conventional R. F. magnetron sputtering system with two independent plasmas not simultaneous focus to substrate. We determined the in-plane and in-growth lattice parameters for different Sn concentrations by high resolution X-ray diffraction (HRXRD). We observed that Ge_(1-x)Sn_x layers with low Sn concentrations have pseudomorphic characteristics. But this layers relax at Sn concentrations higher than the ones growth on Ge (001) substrates. Raman spectroscopy confirms the Sn concentrations of the Ge_(1-x)Sn_x layers. We also determined the band gap transitions and we found that the indirect-direct band gap crossover occurs as is predicted in Ge_(1-x)Sn_x alloys growth on Ge (001).