High-Current-Density Enhancement-Mode Ultrawide-Bandgap Algan Channel Metal-Insulator-Semiconductor Heterojunction Field-Effect Transistors With A Threshold Voltage Of 5 V

Enhancement-mode ultrawide-bandgap Al0.65Ga0.35N/Al0.4Ga0.6N metal-insulator-semiconductor heterojunction field-effect transistors are demonstrated using fluorine-plasma treatment for threshold voltage control and Al2O3 as gate dielectric. The device exhibits a threshold voltage of 5 V, a maximum drain current density of 105 mA mm(-1), and a transconductance of 19 mS mm(-1). In addition, the capability to achieve low off-state current density at 3-4 x 10(-9) mA mm(-1), an exceptionally low gate leakage current density of 1.4 x 10(-8) mA mm(-1) even at a high forward gate bias of V-GS = 12 V, and a current on/off ratio >10(10) is shown. Small signal measurement shows that the device has a unity current gain cutoff frequency f(T) of 3.8 GHz and power gain cutoff frequency f(max) of 4.5 GHz.