SCHEDULED MAINTENANCE
Silane controlled three dimensional GaN growth and recovery stages on a cone-shape nanoscale patterned sapphire substrate by MOCVD
Abstract
Three dimensional (3D) growth induced by silane was performed on cone-shape nano-scale patterned sapphire substrates (NPSS) by metal organic chemical vapor deposition (MOCVD). The growth evolution for the silane controlled 3D growth process and the recovery stage were investigated by a series of growth interruptions. The GaN epilayers grown on the templates with different 3D growth conditions were characterized by X-ray diffraction (XRD), Raman scattering, and atomic force microscopy (AFM) measurements. The full width at half maximums (FWHMs) of the (002) and (102) reflections in the XRD rocking curves were 267 and 324 arcsec, respectively, for the sample on NPSS with 600 s of 3D growth. An extremely smooth surface was achieved with an average roughness of 0.10 nm over 3 × 3 μm2. All the above data were superior to those for the planar sample or the NPSS ones without the optimized 3D growth time. The silane addition caused effective 3D growth. The size, homogeneity, and faceted sidewalls of the islands by the 3D growth led to a high crystalline quality, much strain relaxation and a specular surface for the GaN epilayers.
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