Designs of GaN-based terahertz quantum cascade lasers for higher temperature operations

The GaN-based terahertz quantum cascade laser (THz-QCL) structures reported so far do not have gains sufficient for lasing due to broadenings of subband levels caused by the very strong LO phonon-electron interaction. We propose a novel GaN-based two-well THz-QCL structure unaffected by the subband level broadenings and confirm that it has an adequate gain even at 300 K by using the non-equilibrium Green's function method.