Density Functional Theory Study of the Surface Coverage of H, OH, and O Functional Groups on Diamond (100) Surfaces

Diamond has unique geometric and electronic properties that make it superior to other semiconductors. It can be used for many device applications, such as RF field-effect transistors, power amplifiers, and gas sensors. Since the bulk diamond exhibit insulating properties, diamond surfaces with (100) phase are widely used for electronic applications. When diamond (100) surfaces are terminated with hydrogen- or oxygen-related species, the electrochemical properties are changed by using various degrees of surface coverage. In this research, various degrees of surface coverage of H, OH, and ether groups terminated on the top carbon layer of diamond (100) surfaces were computationally studied using Density Functional Theory (DFT). The adsorption energies were calculated to predict the most favorable type and coverage. The band structures and density of states were determined to explain the electronic properties of each terminating system as the amount of adsorbate types vary. Our results provides an insight into the feasible models of H- and O-terminating species adsorbed on diamond (100) surfaces observed in the experiment. Our theoretical findings will also provide critical pathway to enhance the surface properties of the diamond surfaces for RF device applications.