High-mobility, low-resistive boron-doped diamond material realized by oxygen assistance

The effect of trace oxygen on the light-doping behavior of boron in diamond films during microwave plasma chemical vapor deposition was experimentally investigated. Boron-doped diamond films were grown continuously under different oxygen concentrations oxygen/carbon (O/C) = 0%–5%. When oxygen was added during the diamond doping process, improvements in crystal quality and surface morphology were observed, and residual nitrogen was significantly suppressed. However, further increasing the oxygen concentration could lead to surface defects. We evaluated and discussed the carrier mobility, carrier concentration and boron content of the samples. At room temperature, under the condition of O/C = 4%, the maximum hole mobility reached 1400 cm²⋅V⁻¹⋅s⁻¹, and a higher carrier concentration of 1.5 × 10¹⁵ cm⁻³ was obtained, which is an excellent result compared with all previous studies. In addition, the characteristic peaks that appeared in both low-temperature photoluminescence spectra and absorption spectra were analyzed, and it was found that the characteristic peak at 4.7 eV (270 nm) may correspond to a boron-nitrogen complex, supplementing the effect of boron-doped diamond on defect formation. These findings demonstrate the potential of controlling the boron concentration in diamond films using oxygen concentration in a plasma environment and open avenues for future applications in advanced optoelectronic devices.