A novel β-Ga₂O₃ HEMT with f_T of 166 GHz and X-band P_OUT of 2.91 W/mm

In this paper, a novel β-Ga₂O₃ high electron mobility transistor (BGO-HEMT) with record-high intrinsic unity current gain cut-off frequency (f_T) of 166 GHz and RF output power (P_OUT) of 2.91 W/mm is demonstrated through 2D device simulations using an appropriate negative differential mobility model. The highly scaled proposed device uses 10 nm AlN barrier layer on 50 nm β-Ga₂O₃ buffer with gate-length (L_G) of 50 nm and aspect-ratio (gate length to barrier thickness) of 5 ensures significant gain in high-frequency performance. The novel device design offers very low access and dynamic resistance due to highly doped n⁺ access regions, and a finite gap between ohmic contacts and barrier layer to mitigate source choking effect. The device's superior DC and RF performance is well supported by large two-dimensional electron gas (2DEG) density (n_s) of the order of 10¹³ cm⁻² due to large band discontinuity in AlN/β-Ga₂O₃ heterostructure and highly polarized AlN material. The device shows maximum drain current density (I_DMAX) of ~11.5 A/mm and peak transconductance (g_m) of 0.917 S/mm at V_DS = 15 V and V_GS = 0 and − 7 V respectively. Furthermore, the term 2π (f_T × L_G) for the device shows a value of 0.5 × 10⁷ cm/s, very close to v_sat of 1.5 × 10⁷ cm/s in β-Ga₂O₃. These promising results enhance the potential of β-Ga₂O₃ for future high power RF and microwave applications.