Effect of low-energy ion impact on the structure of hexagonal boron nitride films studied in surface-wave plasma

Abstract

A high-density surface-wave plasma source is used to deposit hexagonal boron nitride (hBN) films in a gas mixture of He, H2, N2, Ar, and BF3 under a high ion flux condition using low-energy ion irradiation. The ion energy is controlled between around zero and 100 eV by applying a negative or positive bias voltage to a substrate, while the ion flux is increased by locating a substrate upstream in the diffusive plasma. For ion energies above ∼37 eV, the structure of the films depends upon ion energy more than substrate temperature, typical of subplantation processes. As a result, the structural order and crystallinity of sp2-bonded phase in the films characterized by Fourier transform infrared spectroscopy and X-ray diffraction are increased with decreasing ion energy, while the mass density of the films characterized by X-ray reflectivity is retained relatively high with a slight dependence upon ion energy.