DC and RF analysis of ScAlN/GaN/β-Ga2O3 and ScAlN/InGaN/GaN/β-Ga2O3 HEMTs on SiC substrate

Abstract

Scandium aluminum nitride (Sc_xAl_1-xN) is a promising material among group III nitrides, offering outstanding polarization properties resulting in very large carrier densities. We report the comparative analysis of Sc_0.18Al_0.72N/GaN/β-Ga₂O₃ and Sc_0.18Al_0.72N/InGaN/GaN/β-Ga₂O₃ HEMTs on Silicon carbide substrate. L_G = 55 nm, Sc_0.18Al_0.72N/GaN/β-Ga₂O₃ HEMT demonstrated maximum current density (I_DS) of 4.38 A/mm, very large carrier density (n_s) of 2.34 × 10¹³ cm⁻², large breakdown voltage (74 V) with low on-resistance (R_on ∼ 0.2 Ω mm), and cut-off frequency (f_T)/maximum oscillation frequency (f_max) of 220/242 GHz. Introduction of a very thin 5 nm In_0.1Ga_0.9N layer in the channel, further improves the 2DEG (two-dimensional electron density), drain current, breakdown voltage. Furthermore, Sc_0.18Al_0.72N/InGaN/GaN/β-Ga₂O₃ heterostructure shows stable transconductance (g_m) over wide gate bias. A gate voltage swing (GVS) of 7.72, I_DS of 6.08 A/mm, and V_BR of 105 V with R_on ∼ 0.138 recorded. These findings show the merits of scandium aluminium nitride barrier material, which enables the HEMTs for next generation radar and telecommunications.