Radiation Defect Engineering in Hexagonal Boron Nitride Films

Hexagonal boron nitride (hBN) is a wide-band-gap semiconductor with several emerging applications. Ion bombardment can be used to fine-tune hBN properties for specific applications. However, the synthesis of wafer-scale hBN films with desired characteristics and thicknesses exceeding ~50 nm remains challenging. Here, we describe radiofrequency-plasma-assisted deposition of polycrystalline hBN films. Film growth is guided by simulations and in-situ plasma diagnostics. We show how the main properties of as-grown films can be controlled by the deposition source design and process variables. We then systematically study damage buildup in these hBN films irradiated with kiloelectronvolt energy ions with different masses (He, N, Ne, Ar, and Xe) and dose rates. Irradiation experiments are complemented by molecular dynamics simulations of the formation and evolution of point defects. Emphasis is on the role of BN polymorphism and transitions between cubic and hexagonal BN phases under ion bombardment. Our results reveal a critical role of intra-cascade defect processes in hBN damage buildup.<br/>This work was performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.