DC and RF Characteristics in Al_2O_3/Si_3N_4 Insulated-Gate AlGaN/GaN Heterostructure Field-Effect Transistors

摘要

Al_2O_3/Si_3N_4 insulated-gate AlGaN/GaN heterostructure field-effect transistors (HFETs) have been fabricated, where excellent RF characteristics have been obtained in addition to the low gate leakage current as the result of employing the metal-insulator-semiconductor (MIS) structure. In an HFET with a gate length (L_g) of 0.1 μm, the cutoff frequency (f_T) and maximum oscillation frequency (f_(max)) were estimated to be 70 and 90 GHz, respectively. The drain current density (I_d) and transconductance (g_m) were 1.30 A/mm and 293 mS/mm, respectively. The gate leakage current (I_g) was as low as 4 x 10~(-5) A/mm even at a forward bias voltage of +3 V.