Oxidized-Silicon-Terminated Diamond p-FETs With SiO2-Filling Shallow Trench Isolation Structures

Herein, excellent electrical performances were achieved for the oxidized-silicon-terminated (C-Si-O) diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) using chemical-vapor-deposition grown SiO2 as the filling insulator of shallow-trench-isolation (STI) structures and gate oxide. The C-Si-O interface was formed under the initial SiO2 layer ( 1^{\text {st}} SiO _{{2}}{)} as a mask during heavily boron-doping growth. The surface carbon-rich layer formed on the mask during selective diamond regrowth was removed using the oxygen plasma ashing treatment. The device having a 130-nm-thick SiO2 gate insulator exhibited subthreshold slopes (S S) of 220-710 mV/dec between 473 and 673 K. A normally-off operation was confirmed at 673 K. The SiO2filling insulator ( 2^{\text {nd}} SiO _{{2}}{)} containing positive fixed charges can block the hole transport channels, and the active regions of the device are out of one plane using the STI structures. Accordingly, OFF-state drain leakage current was successfully suppressed. Consequently, high on-off ratios of 10^{{6}} - 10^{{7}} that cannot be realized in hydrogen-terminated (C-H) diamond FETs were confirmed up to 673 K. To summarize, results of this study provide new strategies for advancing diamond devices from the laboratory to industrial applications.