X-ray study of III-Nitride epitaxial layers



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Group III-Nitride semiconductors are currently under extensive investigation as promising materials for optoelectronic, high-temperature, and high-power devices due to properties such as large direct band gap, high thermal stability, and strong inter-atomic bonds. The performance of III-Nitride epitaxial devices depend heavily on their structural quality. Thin epitaxial semiconducting films usually contain high density of structural defects and a high degree of mosaicity; the III-Nitrides in particular have these properties due to the lack of a natural substrate. In this thesis we study the mosaic nature of III-Nitride epitaxial layers and their characteristics like tilt angle, twist angle, interdependence factor (m). We also discuss methods to accurately determine the density of edge and screw dislocations in an epitaxial film.

In the latter part of the thesis we show the effect various growth parameters have on the structural and electrical properties of GaN: Mg, grown by MOCVD. The data for the study of GaN:Mg epitaxial layers was obtained using a high resolution X-ray diffractometer (XRD). Methods discussed earlier in the thesis were employed on the data to analyze critical structural information of the thin GaN films, with an ultimate aim of improving their electrical, structural, thermal and optical properties.