Structural and Electronic Properties of Atmospheric Functionalized Diamond (100) Surfaces with Variable Coverage

Abstract

Diamond is an optimal material for devices in extreme environments, given its exceptional structural, thermal, and electronic properties. However, its surface properties demonstrate high sensitivity to atmospheric contamination, necessitating rigorous analysis of the surface coverage. This study employed density functional theory (DFT) to investigate diamond (100) surfaces with various terminations, including hydrogen (H), hydroxyl (OH), oxygen in ketone (Oketone), and ether (Oether) configurations, at various coverage levels. At full coverage, the Oether termination, where the O atoms bridge two surface carbons, demonstrated the highest thermodynamic stability. In contrast, at partial coverage, the Oketone configuration, with C atoms doubly bonded to O, emerged as the preferred state. The H-terminated surface exhibited a comparatively lower stability across all coverage levels. Electronic structure analysis indicated that the OH-terminated surface had the largest bandgap at full coverage, followed by H, Oether, and Oketone. Furthermore, increasing the O-based terminations induced a p-to-n-type conductivity transition. The findings also demonstrate that a minimum coverage of 50\% is essential for establishing clear structural-electronic correlations. In conclusion, this investigation highlights the influence of adsorbate type and coverage on the diamond surface stability and electronic properties, offering critical theoretical insights for the design of stable, high-performance diamond-based devices.

Keywords: Diamond surfaces, Surface functionalization, Density Functional Theory (DFT), Adsorbates, Band gap, Conductivity