Surface transfer doping of diamond using solution-processed molybdenum trioxide

Abstract

The surface of hydrogen-terminated diamond (H-terminated diamond) supports a p-type surface conductivity when interfaced with high electron-affinity surface acceptors through the surface transfer doping process. High electron-affinity transition metal oxides (TMOs), such as MoO3, have been regarded as superior candidates in surface transfer doping of diamond, holding great promise for enabling practical diamond electronic devices. In this work, a simple, solution-processed method is demonstrated to deposit a molybdenum trioxide (MoO3) layer on H-terminated diamond surface to achieve surface transfer doping of diamond. The surface of diamond following the deposition of solution-processed MoO3 (sp-MoO3) experienced significant reduction in sheet resistivity, corresponding to an increase in hole density, compared with the pristine air-doped diamond. This hole accumulation layer induced by sp-MoO3 is thermally stable up to 450 °C, and demonstrates metallic conductivity down to 250 mK with a strong spin-orbit interaction (SOI) in the induced two-dimensional (2D) surface conducting layer. Our study demonstrates that sp-MoO3 is comparable with thermally-evaporated MoO3 in doping performance but with great advantage as a simple, inexpensive and highly flexible fabrication method for developing diamond electronics.