The Effect of Hydrogen, Hydroxyl, and Oxygen Surface Coverage on Structural and Electronic Properties of Diamond (100) Surfaces

Diamond has unique structural, thermal, and electronic properties that make it an interesting material for many device applications that operate in extreme conditions, such as radio-frequency field-effect transistors, power amplifiers, and communication satellites. To utilize the unique surface dependent electronic properties of the diamond surface, a comprehensive understanding of the surface adsorbate types and coverage is required. In this study, we performed Density Functional Theory (DFT) calculations of diamond (100) surfaces terminated with various percent coverages of H, OH, and O in ketone configuration (O_ketone), and O in ether configuration (O_ether). Between 25 to 75% coverages, O_ketone, where the O atom is doubled bonded with the surface C atom, was the most favorable. At 100% coverage, O_ether, where the O atom is bridged between the two surface C atoms, was the most favorable. Analysis of the electronic properties revealed that at 100% coverage, O_ketone had the smallest bandgap, followed by O_ether, H, and OH. Combinations of OH, O_ketone, and O_ether mixed with H produced a range of electronic properties that can provide flexibility in designing diamond-based devices. Overall, having various degrees of surface coverage of different functional groups terminated on the surface leads to the modification of electronic properties for engineering diamond surfaces.