Hydrogen-terminated diamond field-effect transistor with AlO _x dielectric layer formed by autoxidation

Fabrication of hydrogen-terminated diamond (H-diamond) field-effect transistor (FET) with AlO _x dielectric layer has been successfully carried out. The AlO _x layer was formed by auto-oxidizing 6 nm Al film in the air at room temperature, and a FET without AlO _x dielectric layer has also been fabricated for comparison. For both FETs, 100 nm Al layers were deposited as the gate electrodes, respectively. The leakage current density in FET with AlO _x dielectric layer was four magnitude orders lower than that without AlO _x dielectric layer at V _GS = −5 V, indicating that AlO _x dielectric layer could effectively reduce leakage current and prevent reverse I _D in I _D − V _DS caused by defects on diamond surface. Distinct pinch-off characteristic with p-type channel was observed in I _D − V _DS measurement. The threshold voltage was −0.4 V at V _DS = −15 V.