Assembly of a high-dielectric constant thin TiO_x layer directly on H-terminated semiconductor diamond

A high-dielectric constant (high-k) TiO_x thin layer was fabricated on hydrogen-terminated diamond (H-diamond) surface by low temperature oxidation of a thin titanium layer in ambient air. The metallic titanium layer was deposited by sputter deposition. The dielectric constant of the resultant TiO_x was calculated to be around 12. The capacitance density of the metal-oxide-semiconductor (MOS) based on the TiO_x/H-diamond was as high as 0.75 μF/cm² contributed from the high-k value and the very thin thickness of the TiO_x layer. The leakage current was lower than 10⁻¹³ A at reverse biases and 10⁻⁷A at the forward bias of −2 V. The MOS field-effect transistor based on the high-k TiO_x/H-diamond was demonstrated. The utilization of the high-k TiO_x with a very thin thickness brought forward the features of an ideally low subthreshold swing slope of 65 mV per decade and improved drain current at low gate voltages. The advantages of the utilization high-k dielectric for diamond metal-oxide semiconductor field effect transistors are anticipated.