Investigation of n-type GaN deposited on sapphire substrate with different small misorientations

The ntype GaN films have been grown on cplane sapphire with different small misorientation（0°—03°）by metalorganic chemical vapor deposition. It was observed by atomic force microscopy that the ntype GaN has the step flow growth mode, the flow steps of the ntype GaN surface are uniformly distribution on 02° and 03° misorientation sapphire substrate, it was observed clearly that random and poor distribution of the flow steps was caused by the step reconstruction on 0° misorientation sapphire substrate. The image quality parameter of electron backscatter diffraction indicated that the strains increase as the ntype GaN epilayer thickness increases on 0° misorientation sapphire substrate but do not vary obviously on 02° and 03° misorientation sapphire substrates. Electrical and optical properties demonstrated the ntype GaN grown on the 02° and 03° misorientation sapphire substrates have higher electron concentration and lower ratio of the intensity of yellow band to near band edge.