ZnO/Zn1−xMgxO QCL: A high power room temperature THz source

We propose a ZnO/Zn_1-xMg_xO quantum cascade laser (QCL) operating at room temperature as a possible candidate for the generation of THz radiation. In this work, theoretical designs of ZnO/ZnMgO QCLs emitting at 50μm (ΔE=24.5meV) are presented and compared with GaN/AlGaN (at 58.43μm, ΔE=21.23meV), GaN/InGaN (at 52.59μm, ΔE=23.59meV), and GaAs/InGaAs (at 53.33μm, ΔE=23.26meV). The theoretical calculation is based on basic device physics, taking into account electron LO-phonon, spontaneous and piezoelectric polarizations, and related strain induced effects on the energy band profile. The calculated output power of ZnO/Zn_0.95Mg_0.05O is 24% higher than that of GaN/Al_0.05Ga_0.95N, 4% higher than that of GaN/In_0.05Ga_0.95N, and 11% higher than that of GaN/In₀.05Ga₀.95As. A wall plug efficiency of 26% is obtained in ZnO/Zn_0.95Mg_0.05O.