Terahertz Absorption in Quantum Devices Based on MgxZn1−xO/ZnO Quantum Well Structures

Abstract

The energy level structures of MgxZn1−xO/ZnO/MgxZn1−xO quantum wells (QWs) with various geometrical structures and material compositions are obtained. Terahertz (THz) intersubband absorption can be realized and tunable with x in the range of 0.01~0.04 and well width in the range of 5~13 nm. Electron scattering such as piezoelectric acoustic phonon (PAP), polar optical phonon (POP), interface roughness (IFR), and random alloy (RAS) scattering are included in the calculations to analyze the linewidth broadening. Increasing the Mg composition or decreasing the well width can obtain high-frequency THz intersubband absorption, in which case IFR is found to be the physical mechanism that makes the linewidth broaden. On the other hand, the influence difference of PAP scattering for the lower Mg composition, which may be caused by the different electro-mechanical coupling coefficients (EMCC), is obviously larger than that for the higher Mg composition, meaning that the accurate value of EMCC is much more important for the THz intersubband absorption in MgxZn1−xO/ZnO/MgxZn1−xO QWs with a smaller x. The findings are helpful in the design of THz detector devices.