Control of band offsets qt high-index semi conductor interfaces by the Piezo-effect induced with thin strained insertion layrs

点击翻译按钮获取中文摘要

We have theoretically studied the electronic structure of an InAs monolayr on a (311) GaAs substrate by using the semi-empirical sp^3s^<**> tight-binding method. (InAs)_1/(GaAs)_n[311] superlattices with n=10-26 are used for calculations. The (311)-InAs monolayr induces an electron level (near the conduction-band edge) and a hole level (near the valence-band edge) in the GaAs band-gap. The electron-hole energy separation is smaller than the GaAs band-gap energy by 0.06eV (n=10) and 0.03eV (n=26), which accounts for the observed photoluminescence peak [M.I.Alonso et al. : Phys. Rev. B50,1628 (1994)]. The charge densities of the electorn state and the hole state are weakly lacalized near the (311)-InAs monolayr. Next, we have studied the strain energy distribution and electronic structure of InAs pyramidal quantum dots (QDs) with uncovered surfaces. Using the sp^3s^<**> tight-binding method, we calculate the densities of states for the inside states and the surface states. The density of the inside states shows a large energy gap ; 2.71-1.74eV for 161-1222-atom QDs. At the same time, we find the surface states in the gap.