An enhancement-mode C-H diamond FET with low work function gate material gadolinia

Enhancement-mode hydrogen-terminated diamond (C-H diamond) field effect transistors (FETs) are strongly desirable for safety protection, energy saving, etc., and low work function gate material is an effective and convenient way to deplete the two-dimensional hole gas and realize the enhancement-mode. In this article, we demonstrate a C-H diamond FET with low work function gadolinia (Gd2O3) gate materials. For the 4 μm gate length (LG) Gd2O3 C-H diamond FET, the device demonstrates an obvious enhancement-mode with a threshold voltage of −1.3 V. Besides, the maximum source/drain current density and the leakage current density are −80.0 mA/mm and 1.6 × 10−6 A/cm2 at a gate voltage of −7 V, respectively. Moreover, the device demonstrates a saturation carrier mobility of 437.3 cm2/V · s. Accordingly, this enhancement-mode C-H diamond Gd2O3 FET demonstrates high performance with relatively high source/drain current density and low leakage current density, which will provide a strategy for the development of enhancement-mode C-H diamond FETs significantly.