Microstructure and dislocation of epitaxial InN films revealed by high resolution x-ray diffraction

Abstract

This article reports on the study of microstructure and dislocation of InN films using high resolution x-ray diffraction grown on sapphire (0001) both by metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE). The mosaic tilt, twist, and correlation lengths of InN films are determined by using symmetrical and asymmetrical reflections as well as reciprocal space mapping. Deducing from these results, MBE-grown InN film exhibits the edge-type dislocations of 4.0×109 cm−2, which is about ten times higher than the density of screw-type dislocations. In MOCVD-grown InN sample, the edge-type dislocations density is as high as 2.1×1010 cm−2, and the screw-type dislocations density is 1.3×109 cm−2. They indicate that edge type is the predominant dislocation type in the InN films. By comparing the reported transmission electron microscopy results, the accuracy of evaluation for the dislocation density using the mosaic model is proved.

Formation of interfacial misfit dislocation in GaSb/GaAs heteroepitaxy via anion exchange process

“…Thus, a qualitative comparison of the threading dislocation density belonging to different samples can be obtained by comparing the FWHM of the XRD rocking curves taken from these samples, provided they have an identical layer structure and provided the measurements were performed using identical XRD system configurations. Furthermore, it was understood that the FWHM of a symmetrical plane ω-scan rocking curve is sensitive to the presence of screw-type dislocations, while edge-type dislocations can be reflected in the FWHM of an asymmetrical plane ω-scan rocking curve [27]. Thus, in this report, ω scans were conducted on all samples at a symmetrical (004) plane and an asymmetrical (224) plane.…”

Growth of aluminium nitride with linear change of ammonia flow

“…XRD analysis of epitaxial AlN layers is usually performed using the mosaic model of crystals [13,14]. In this model it is assumed that the layer consists of crystallites (mosaic blocks), each of which coherently scatters X-rays.…”

Structural properties of GaN(0001) epitaxial layers revealed by high resolution X-ray diffraction

“…L = However, this method includes a large error [7]. Hence, the RSM of the GaN asymmetric lattice planes is used as an alternative [11,12].…”

“…The solid line in Figure 6 is utilized to extrapolate FWHMs of asymmetric planes versus inclination angles to 90 degrees and reach the twist angle [11,14], as in the model of Srikant et al In this case, the result of the twist angle is about 0.39 degrees, which is in good agreement with the result, 0.4, calculated from direct φ measurements [7]. Considering that the density of edge-type dislocations is where b e is the Burgers vector of edge-type dislocations, the result obtained is 2.516×10 10 cm −2 .…”