Electrical Properties of H-Diamond Field Effect Transistor With ZrO₂/HfO₂ Stacked-Gate Deposited by Electron Beam

Electrical properties of H-diamond field effect transistor with ZrO₂/HfO₂ stacked gate deposited by electron beam have been investigated in this letter. Due to the fixed positive charge in ZrO₂ contact layer, both devices exhibit normally-off operation. Compared with ZrO₂ monolayer gate sample, the ZrO₂/HfO₂ stacked-gate device showed an order of magnitude improvement in gate leakage current (~3.5 × 10⁻⁶ A/cm² at V_GS= −5 V), on/off ratio (10⁹), SS (138 mV/dec @ V_GS= −0.2 V) and a relatively higher I_Dmax of −50 mA/mm at V_GS= −6 V. Therefore, the ZrO₂/HfO₂ stacked-gate is a promising gate dielectric to improve the performance of H-diamond FETs.