Grazing incidence X-ray topographic studies of threading dislocations in hydrothermal grown ZnO single crystal substrates

ZnO single crystal substrates grown by the hydrothermal method have been characterized by grazing incidence X-ray topography using both monochromatic and white synchrotron X-ray beams. 1124 reflection was recorded from the (0001) wafers and the different contrast patterns produced by different threading defects were noted. To uniquely identify the Burgers vectors of these threading dislocation defects, we use ray tracing simulation to compare with observed defect contrast. Our studies showed that threading screw dislocations are not commonly observed. Most threading edge dislocations have the Burgers vector of 1/3 [2110] or 1/3 [1210]and a density of 2.88×10⁴/cm ².