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DEFECT SELECTIVE ETCHING OF THICK AlN LAYERS GROWN ON 6H-SIC SEEDS – A TRANSMISSION ELECTRON MICROSCOPY STUDY
Published online by Cambridge University Press: 01 February 2011
Abstract
In the present study, the type and densities of defects in AlN crystals grown on 6H-SiC seeds by the sublimation-recombination method were assessed. The positions of the defects in AlN were first identified by defect selective etching (DSE) in molten NaOH-KOH at 400 °C for 2 minutes. Etching produced pits of three different sizes: 1.77 ìm, 2.35 ìm , and 2.86 ìm. The etch pits were either aligned together forming a sub-grain boundary or randomly distributed. The smaller etch pits were either isolated or associated with larger etch pits. After preparing cross-sections of the pits by the focused ion beam (FIB) technique, transmission electron microscopy (TEM) was performed to determine which dislocation type (edge, mixed or screw) produced a specific etch pit sizes. Preliminary TEM bright field and dark field study using different zone axes and diffraction vectors indicates an edge dislocation with a Burgers vector 1/3 is associated with the smallest etch pit size.
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- Copyright © Materials Research Society 2008
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