High mobility p -type doping of hexagonal boron nitride films on diamond (100) substrates

The heteroepitaxy of hexagonal boron nitride (h-BN) on diamond exhibits significant potential for the advancement of diamond-based electronic devices. p-Type doping of h-BN is expected to provide sufficient carriers for forming a two-dimensional hole gas at the diamond interfaces. However, high-mobility doping of h-BN remains challenging. Here, we report the in situ growth of magnesium-doped h-BN films on single-crystal diamond (100) substrates using radio frequency magnetron sputtering, followed by an annealing treatment in the same vacuum chamber. The resultant h-BN films exhibit dense and atomically smooth surfaces with roughness below 1 nm, as well as uniform doping profiles within the films. Both x-ray photoelectron spectroscopy and secondary ion mass spectroscopy reveal the presence of Mg–N bonds, suggesting the successful incorporation of Mg atoms. The successive annealing treatment after growth further improved the activation efficiency of the dopants. Hall effect measurements revealed distinct p-type conductivity, with hole mobility increasing to 222 cm2/V s and resistivity decreasing by over three orders of magnitude. These results demonstrate an effective and feasible route for achieving high-mobility p-type h-BN films directly on diamond substrates, which are essential for developing high-performance diamond-based electronics.