Nanocrystalline Hexagonal Boron Nitride Thin Films Deposited by Dynamic Glancing Angle Deposition for UV-Emitting Devices and Detectors

This study investigates thin films of hexagonal boron nitride (h-BN), a promising material for the development of UV optoelectronic and wide-band gap semiconductor applications. A comprehensive analysis of the structural and optical properties of h-BN films deposited by radio frequency sputtering, using both stationary and Dynamic Glancing Angle Deposition (DGLAD) techniques, demonstrates that the film nanostructure can be effectively tailored by controlling key deposition parameters such as substrate bias, deposition plasma composition, and substrate oscillation. The introduction of hydrogen into the deposition atmosphere promotes the formation of turbostratic polycrystalline films with tunable crystallite sizes and significantly impacts the bonding environment, leading to a controlled shift of the optical band gap from ∼3.7 to ∼4.2 eV. Substrate oscillation modulates the angle of precursor impinging on the substrate, influencing the nano- and microstructure of the films and their optical properties. The physical characteristics introduced by the specific method of preparation of h-BH, such as morphological and topographical features, were characterized via SEM and AFM. At the same time, photoluminescence (PL) measurements revealed defect-related emission states, highlighting the influence of structural disorder on radiative transitions. Importantly, the DGLAD approach emerges as a useful strategy to engineer the structural and optical features of the h-BN films. The reported findings provide valuable insights into the correlation between growth dynamics, crystallographic disorder, and optoelectronic properties, reinforcing the potential of h-BN for integration into UV photodetectors, light-emitting devices, and other possible wide-bandgap electronic applications such as sensors.