Fabrication of gallium nitride on sapphire via pulsed laser deposition under different pressure energy

High oriented (002) gallium nitride (GaN) thin film is manufactured on 2inch c-plane oriented sapphire by pulsed laser deposition (PLD). The target we used was polycrystalline GaN target. During the growth of GaN, nitrogen gas was purged and the pressure is controlled at 10 mtorr while the temperature and energy are optimized. The surface roughness is measured by atomic force microscopy (AFM) while the morphology is investigated by scanning electron microscopy (SEM). The crystallinity is measured by X-ray diffraction (XRD). When the temperature is elevated, both the film quality and surface roughness are greatly improved. On the other hand, the best growing condition for different energy lies on 350 mJ at 800°C. The surface roughness is as small as 0.93nm that has never reported before. The crystallinity of GaN thin film under this condition is also the best.