Design and simulation of terahertz GaN/Al/sub 0.15/Ga/sub 0.85/N quantum cascade laser

We propose the idea of developing THz quantum cascade lasers (QCLs) with GaN-based quantum well (QW) structures with significant advantages over the currently demonstrated THz lasers in the GaAs-based material system. While the ultrafast longitudinal optical (LO) phonon scattering in AlGaN/GaN QWs can be used for the rapid depopulation of the lower laser state, the large LO-phonon energy (/spl sim/90 meV) can effectively reduce the thermal population of the losing states at higher temperatures. Our analysis of one particular structure has shown that a relatively low threshold current density of 832 A/cm can provide a threshold optical gain of 50/cm at room temperature. We have also found that the characteristic temperature in this structure is as high as 136 K.