Influence of SiH4 treatment time on the properties of GaN films grown on in-situ SiNx patterned sapphire substrate

Sapphire substrate was treated by SiH₄ under NH₃ atmosphere and nano-size islands SiN_x mask was formed on the surface. GaN films were grown on the SiN_x-patterned sapphire substrates to form GaN/SiN_x/Al₂O₃ structure. The influence of SiH₄ treatment time on crystalline quality and luminance properities of GaN films were studied. The lowest density of screw and edge type dislocations of 1.3×10⁸ cm^-2 and 5.0×10⁹cm^-2 was got by SiH₄ treatment time of 120s, together with the lowest FWHM of GaN PL spectra of 5.4nm. The result indicated that SiH₄ treatment time could affect the size and density of SiN_x islands. The SiN_x mask with modified SiH₄ treatment time increased 3D to 2D growth time of high temperature GaN, which was the major factor improving the crystalline quality of GaN films.