Surface Oxygen Adsorption and Electric Property of Hydrogen-Terminated Single Crystal Diamonds by UV/ozone Treatment**Supported by the National Natural Science Foundation of China under Grant Nos. 51672102 and 51972135.

Abstract

Surface terminations of diamond play an important role in determining the electric properties of diamond-based electronic devices. We report an ultraviolet/ozone (UV/ozone) treatment process on hydrogen-terminated single crystal diamond (H-diamond) to modulate the carrier behavior related to varying oxygen adsorption on surfaces. By UV/ozone treatments, the induced oxygen radicals are chemically adsorbed on the H-terminated diamond and replace the original adsorbed H, which is analyzed by x-ray photoelectron spectroscopy. The concentration of oxygen adsorbed on surface increases from ∼3% to ∼8% with increasing the ozone treatment time from 20 s to 600 s. It is further confirmed by examining the wettability properties of the varying diamond surfaces, where the hydrophobic for H-termination transfers to hydrophilic for partly O-termination. Hall effect measurements show that the resistance (hole mobility) of the UV/ozone-treated H-diamond continuously increases (decrease) by two orders of magnitude with increasing UV/ozone treatment time from 20 s to 600 s. The results reveal that UV/ozone treatment becomes an efficient method to modulate the surface electrical properties of H-diamonds for further investigating the oxygenation effect on two-dimensional hole gas based diamond devices applied in some extreme environments.