Improvement of the Al2O3/NO2/H-diamond MOS FET by using Au gate metal and its analysis

By using Au as the gate metal contact, performance of NO2-doped H-diamond field effect transistor (FET) has been improved. We fabricated and compared Al2O3 layer deposited, NO2-doped H-diamond FETs with Au, Al and Ti gate metals, respectively. Among them, FET with Au gate metal showed the highest drain current of -61.76 mA/mm, where drain current of FET with Al and Ti gate metals were respectively -42.89 and -39.97 mA/mm. Further, NO2-doped metal-oxide-semiconductor (MOS) structures are fabricated and capacitance-voltage measurements were performed to evaluate the effect of the metal work function and surface barrier height. This phenomenon has been explained in terms of surface barrier height of the Al2O3 layer and metal. Finally, band diagrams of MOS structures are simulated and determined. Band diagrams at various gate voltages are discussed.