Effect of thickness on the microstructure, surface morphology and optical properties of N-incorporated β-Ga2O3 films

To investigate the effect of thickness on the microstructure, surface morphology and optical properties of N-incorporated β-Ga2O3 films, a series of N-incorporated β-Ga2O3 samples with different thicknesses were prepared by radio frequency (RF) magnetron sputtering method. X-ray diffraction measurements show that the crystallinity quality was improved by increasing the film thickness. Atomic force microscopy results show that the surface exhibits hillock and island morphology under different film thicknesses. The optical transmittance of all samples is more than 80% in the visible range. The UV absorption edge shifts to longer wavelength, and the small change in the optical band gap value is due to the improved crystallinity of the films.