Comprehensive review of GaN HEMTs: Architectures, recent developments, reliability concerns, challenges, and multifaceted applications

The emerging need for high-frequency, high-power electronics and biosensors necessitates the demand for high electron mobility transistors (HEMTs) that outperform the mainstream silicon and other direct bandgap materials. Gallium Nitride (GaN)-based HEMTs can operate in both depletion-mode (D-mode) and enhancement-mode (E-mode), and have garnered significant attention for their superior performance in these applications. These wide band-gap semiconductors exhibit significant outcomes in DC as well as RF applications, such as a higher threshold voltage of 8.6 V, transconductance of 680 S/mm with OIP3 (output third-order intercept point) of 41.2 dB, cut-off frequency (fT) of 391 GHz compared to the conventional devices. There are also found some meticulous parameters e.g. breakdown voltage (Vbr) of 1513 V, drain saturation current of 3.41 kA/cm2 with an equivalent noise resistance (Rn) of 1.21 dB and 20 Ω at 20 GHz, a low on-resistance (RON) of 0.00269 Ω-mm, at gate length (LG) of 100 nm in a GaN HEMT by using quaternary InAlGaN barrier is achieved maximum drain current (IDS, max) of 1940 mA/mm while another HEMT with Carbon doped GaN buffer as well as AlGaN back barrier gets Vbr around 2900 V. The RF metrics, like a fT of 200 GHz with moderate LG of 80 nm for AlGaN/GaN HEMT with Si substrate of plasma molecular beam epitaxy, a maximum oscillation frequency (fmax) of 308 GHz, show great impact on High-frequency and microwave applications. Nevertheless, the E-mode outperforms the D-mode HEMTs for secured operations with low leakage loss; there are still some challenges, such as current collapse, short-channel effects, and pinch-off phenomena that persist, impacting device reliability. This review article examines recent advancements in GaN HEMT architectures, emerging materials, and their applications in power and radio-frequency devices, as well as explores future applications in biosensing, satellite, and optical communications.