Oxidized Si terminated diamond and its MOSFET operation with SiO_2 gate insulator

摘要

During selective epitaxial growth of diamond through SiO_2 masks, silicon terminations were formed on a diamond surface by replacing oxygen terminations under the masks. The high temperature of selective growth and its reductive atmosphere possibly allowed Si atoms in SiO_2 to interact with the diamond surface, resulting in silicon terminated diamond (C-Si diamond) composed of a monolayer or thin multilayers of carbon and silicon bonds on diamond. Diamond metal oxide semiconductor field effect transistors (MOSFETs), with a C-Si diamond channel and selectively grown undoped or heavily boron-doped (p~+) source/drain (S/D) layers, have been fabricated. Both the MOSFETs with undoped and p~+ S/D exhibited enhancement mode (normally off) FET characteristics. The drain current (Ids) of the undoped device reached - 17mA/mm with threshold voltage (V_T) -19 V; the p~+ device attained a high I_DS - 165mA/mm with a V_T of -6 Ⅴ being one of the best normally off diamond FETs. Transmission electron microscopy and energy dispersive x-ray spectroscopy confirmed the presence of C-Si diamond under the SiO_2 masking area. The field effect mobility and interface state density at the C-Si/SiO_2 (220 nm)/Al_2O_3 (100 nm) MOS capacitor are 102 cm~2 V~(-1)s~(-1) and 4.6 × 10~(12)cm~(-2)eV~(-1) ,respectively. The MOSFET operation of C-Si diamond provides an alternative approach for diamond.