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

Admittance spectroscopy is used to study hole states in Si$_{0.7-y}$Ge$_{0.3}$Sn$_{y}$/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$_{0.7-y}$Ge$_{0.3}$Sn$_{y}$ layer in the Si matrix are determined using the 6-band $\mathbf{kp}$ method. The valence-band offset at the Si$_{0.7-y}$Ge$_{0.3}$Sn$_{y}$ 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$_{0.7-y}$Ge$_{0.3}$Sn$_{y}$ layers and Si on the tin content is described by the expression $\Delta E_{V}^{\operatorname{exp}}$ = (0.21 $\pm$ 0.01)+(3.35 $\pm$ 7.8 $\cdot$ 10$^{-4})y$ eV.