PHOTOCHEMICAL GROWTH OF GAN AND ALN ON SAPPHIRE (0001) AND GAAS(100)

Stoichiometric gallium nitride and aluminum nitride films have been grown on various substrates at temperatures between 600 and 700-degrees-C by photochemical vapor deposition where the optical source is an excimer laser or a xenon lamp. For GaN, growth rates exceeding 2 mum h-1 have been realized with a feedstock gas stream comprising Ga(CH3)3, NH3 and argon and an ArF laser beam passing about 1 mm above the substrate (parallel geometry). Negligible growth of GaN is observed at 600-degrees-C in the absence of the UV radiation, whereas a 75 W xenon lamp accelerates the film growth rate at 650-degrees-C by 50%. X-ray diffraction shows the films to be fine-grained polycrystalline (wurtzite structure) and preferentially oriented (0001) for GaN grown on basal plane (0001) sapphire and (1010BAR) when the substrate is GaAs(100).