Intersubband Device Modeling of Gallium Nitride High Electron Mobility Transistor for Terahertz Applications

High-electron-mobility transistors (HEMTs) utilizing gallium nitride (GaN)-based heterostructures are potential structures for the development of room temperature terahertz (THz) source and detectors. The corresponding material system also offers immense and exciting physical effects governing its behavior at THz frequencies. This behavioral simulation has been attempted for undoped aluminum gallium nitride/ aluminum nitride /GaN heterostructure for THz applications in the present work using technology computer-aided design platform. Self-consistent solutions of Schrodinger and Poisson equations are solved to calculate quantized energy states. The work also presents physics-based device modeling of GaN HEMT structure using the simulated properties of heterostructure like electron mobility, two-dimensional electron gas concentration, polarization charge concentration, conduction band energies, and so forth. Measurement-based approach has been adopted to increase the reliability of the simulation and modeling. Various semiconductor characterization techniques have been utilized for this purpose. It is studied and presented that intersubband transition phenomenon is possible mode especially at THz frequency and can significantly contribute to extend the GaN-HEMT operating frequency well beyond its present cutoff frequency to THz band.