Electrical Characterization in Ultra-Wide Band Gap III-Nitride Heterostructure IMPATT/HEMATT Diodes: A Room-Temperature Sub-Millimeter Wave Power Source

Fabrication and subsequent on-chip direct current characterization are reported for a vertical-mesa avalanche transit time (ATT) diode. The active region of such diodes consists of a GaN/AlGaN heterostructure. The study has shown that the device has the potential to develop \(1\times {10}^{11}\mathrm{ W}/{\mathrm{m}}^{2}\) RF power at 0.1 THz. An indigenously developed strain-corrected mixed quantum tunneling drift-diffusion (Sc-MQTDD) device simulator has been used for the pre-fabrication design of an ultra-wide band gap (UWBG) III-V semiconductor-based device, and, through performance comparison, the validity of the model has been successfully established. The simulator incorporates relevant aspects of device physics, including strain-induced conduction band modification, subsequent piezoelectric polarization, variation of effective mass, and quantum mechanical tunneling for heterostructures to solve the Schrodinger equation, subject to appropriate modified boundary conditions. Furthermore, a set of studies were carried out to investigate the effects of the mesa orientation/growth plane on the power frequency behavior of III–V devices. Finally, a laterally oriented AlGaN/GaN/AlGaN heterostructure high electron mobility ATT (HEMATT) diode with a two-dimensional electron gas (2-DEG) active region is proposed. The device performance has been estimated using the in-house quantum simulator. To the best of the authors’ knowledge, this aspect of the study is reported for the first time in this paper. Electrical characteristics of the designed HEMATT oscillator yielded a very low parasitic resistance \(\sim 7.3\times {10}^{-10}\Omega {\mathrm{m}}^{-2}\) compared to its vertical-device counterpart. This is due to the significant mobility enhancement in the 2-DEG active region. Consequently, high output power ~\({{P}_{D}^{S}}_{\mathrm{HEMATT}}=1.5\times {10}^{11}\mathrm{ W}/{\mathrm{m}}^{2}\) has been obtained at a high operating frequency ~ 0.4THz.