m-Plane GaN-Based Three-Well THz Quantum Cascade Laser

We present a novel m-plane GaN Terahertz Quantum Cascade Laser (THz QCL) with a 3quantum well (3QW) scheme, analyzed using the Non-equilibrium Green's Function (NEGF) approach. This design offers a practical alternative to the previous Two-Well (TW) GaN THz QCLs. The addition of an extra barrier reduces leakage into the continuum and excited states, significantly lowering operating currents and mitigating thermal damage. By accounting for excited-state leakage-often neglected in prior studies-a peak gain of ~76 cm^-1 at low temperatures, decreasing to ~24 cm^-1 at 300 K, was obtained, matching expected losses and enabling near-room-temperature operation. The laser operates at ~6 THz. This work advances GaN-based THz QCLs towards room-temperature performance and broader frequency operation.