Electrical properties of cerium hexaboride gate hydrogen-terminated diamond field effect transistor with normally-off characteristics

Fabrication of hydrogen-terminated (H-terminated) diamond field effect transistor (FET) with low work function cerium hexaboride (CeB₆) gate material has been successfully performed. For the 8 μm gate length device, the threshold voltage (V_TH) is extracted to be −0.46 V, demonstrating a normally-off characteristics. The maximum drain source current density (I_Dmax) is −83.8 mA/mm, and the competitive I_Dmax may be ascribed to the undamaged two-dimensional hole gas channel. The interface state density (D_it) is evaluated to be 1.93 × 10¹² cm⁻²·eV⁻¹, and the relatively low value may be attributed to the uncontaminated interface in gate material. This work provides a promising strategy to realize normally-off H-terminated diamond FET for fail-safety and energy-efficient power electronic devices.