Characterisation of dislocations in znO by X -Ray imaging

Abstract

Transmission X-Ray topography (X-ray imaging) was used to characterize the density and type of the native dislocations in ZnO substrates. C-oriented ZnO bulk materials from different origins were compared, either high purity Chemical Vapor Transport (CVT) grown or commercial, hydrothermally grown wafers. Elongated dislocations lying within the substrate were found in hydrothermal substrates. In CVT crystals, the density of dislocations was found to be too high for X-ray determination of their Burgers vector. However, in hydrothermal crystals, the density of dislocations were found to be in the range < 10 4 / cm2 and extend mainly within the substrate. Whereas complete Burgers vector identification is not achieved, two kinds of dislocations have been evidenced : grown-in, swirled dislocations ("high" temperature) and linear, gliding dislocations, most probably developped during the cooling steps in (0 1-1 0) glide planes. © Published under licence by IOP Publishing Ltd 2011.