Performance of normally off hydrogen-terminated diamond field-effect transistor with Al₂O₃/CeB₆ gate materials

In this work, we demonstrate a hydrogen-terminated diamond (H-diamond) field-effect transistor (FET) with Al2O3/CeB6 gate materials. The CeB6 and Al2O3 films have been deposited by electron beam evaporation technique, sequentially. For the 4/8/12/15 mu m gate length (L-G) devices, the whole devices demonstrate distinct p-type normally off characteristics, and all the threshold voltage are negative; all the absolute values of leakage current density are 10(-4) A/cm(2) at a V-GS of -11 V, exhibiting a relatively low leakage current density compared with CeB6 FETs, and this further demonstrates the feasibility of the introduction of Al2O3 to reduce the leakage current density; the maximum drain-source current density is -114.6, -96.0, -80.9, and -73.7 mA/mm, which may be benefited from the well-protected channel. For the 12 mu m L-G devices, the saturation carrier mobility is 593.6 cm(2)/V s, demonstrating a good channel transport characteristic. This work may provide a promising strategy for the application of normally off H-diamond FETs significantly.