Comparative Study of III-Nitride Nano-HEMTs on Different Substrates for Emerging High-Power Nanoelectronics and Millimetre Wave Applications

We have investigated the performance characteristics of a III-nitride high electron mobility transistor (HEMT) on different substrates. It exhibits a negative threshold voltage (depletion mode) for a HEMT grown on silicon (Si), silicon carbide (SiC), and sapphire substrates, whereas it shows a positive threshold voltage (enhancement mode) when grown on beta-gallium oxide (β-Ga₂O₃). Compared to Si, SiC, and sapphire, β-Ga₂O₃ improves different parameters, such as off-state leakage characteristics, subthreshold voltage, breakdown voltage (V_BR), and radio frequency (RF) performance. In addition, it shows breakdown voltage characteristics of 4 V, 11 V, 94 V, and 108 V for a HEMT grown on Si, sapphire, SiC, and β-Ga₂O₃ , respectively. It also exhibits cut-off frequencies of 122 GHz, 342 GHz, 380 GHz, and 420 GHz for HEMT using Si, sapphire, SiC, and β-Ga₂O₃ substrates, respectively. Generally, HEMTs suffer from a trade-off between breakdown voltage and frequency characteristics. However, the proposed III-nitride HEMT developed on β-Ga₂O₃ demonstrated an improved breakdown voltage without affecting its high-frequency characteristics. This achievement is mainly because of a better lattice match between the buffer material and the substrate. This research aims to provide a comprehensive understanding of a III-nitride nano-HEMT developed on a β-Ga₂O₃ substrate in order to aid future research in this cutting-edge technology.