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 (f T ) of 391 GHz compared to the conventional devices. There are also found some meticulous parameters e.g. breakdown voltage (V br ) of 1513 V, drain saturation current of 3.41 kA/cm 2 with an equivalent noise resistance (R n ) of 1.21 dB and 20 Ω at 20 GHz, a low on-resistance (R ON ) of 0.00269 Ω-mm, at gate length (L G ) of 100 nm in a GaN HEMT by using quaternary InAlGaN barrier is achieved maximum drain current (I DS, max ) of 1940 mA/mm while another HEMT with Carbon doped GaN buffer as well as AlGaN back barrier gets V br around 2900 V. The RF metrics, like a f T of 200 GHz with moderate L G of 80 nm for AlGaN/GaN HEMT with Si substrate of plasma molecular beam epitaxy, a maximum oscillation frequency (f max ) 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.