A DFT study of the surface charge transfer doping of diamond by chromium trioxide

In this study, a density functional theory method is employed to investigate the surface charge transfer doping of diamond by chromium trioxide (CrO₃) with high electron affinity. Superior surface charge transfer of the hydrogenated diamond surface is demonstrated using CrO₃ as an electron acceptor. The charge density difference and Bader charge analysis reveal that the electrons are transferred from the diamond surface to CrO₃ molecule, leading to the formation of two-dimensional hole gas, and the holes left in the diamond surface increase the conductivity of the diamond surface. The analysis of electronic structure indicates that areal hole density as large as 9.85 × 10¹³cm⁻² for CrO₃-doped diamond surface can be achieved. Besides, the optical absorption near infrared region of the hydrogenated diamond surface is greatly enhanced upon CrO₃ doping, which implies that this CrO₃-doped diamond surface is a promising candidate for optoelectronic materials. The present study provides an in-depth theoretical understanding of the formation of two-dimensional hole gas on diamond surface induced by a new transition metal oxide, and predicts that the CrO₃-doped diamond surface may have important implications in electronic and optoelectronic devices.