Valence-band offsets in strained SiGeSn/Si layers with different tin contents

Admittance spectroscopy is used to study hole states in Si_0.7–yGe_0.3Sn_y/Si quantum wells in the tin content range y = 0.04–0.1. It is found that the hole binding energy increases with tin content. The hole size-quantization energies in structures containing a pseudomorphic Si_0.7–yGe_0.3Sn_y layer in the Si matrix are determined using the 6-band kp method. The valence-band offset at the Si_0.7–yGe_0.3Sn_y heterointerface is determined by combining the numerical calculation results and experimental data. It is found that the dependence of the experimental values of the valence-band offsets between pseudomorphic Si_0.7–yGe_0.3Sn_y layers and Si on the tin content is described by the expression ΔE_V^exp = (0.21 ± 0.01) + (3.35 ± 7.8 × 10^–4)y eV.