Dr Jim Kelly FRAS

BSc(Hons) MSc PhD CertEd CPhys MInstP AIHort

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Polytypism and One-Dimensional Disorder in Silicon Carbide

Jim Kelly's main scientific research interest is in Synchrotron Diffraction Topography of polytype layers and defects in semiconductor silicon carbide. Polytype coalescence in Lely vapour grown silicon carbide (SiC) has now been studied extensively using the technique of X-Ray Diffraction (XRD). These experiments were performed on Station 7.6 of the Daresbury Synchrotron Radiation Source (SRS). The technique of Synchrotron Topography (SRS-XRDT) has been used to provide diffraction contrast from the edge rather than the more substantial faces of the SiC crystals, with a white beam of continuous wavelength X-rays. Using this novel methodology a unique database has been built up of the spatial distribution of one-dimensional disorder (1DD) and regions of high defect density < 5 mm between the adjoining common polytypes (6H, 4H and 15R) and Long Period Polytypes (LPP's). Next nearest neighbour relationships have prompted a model termed an American club sandwich to be proposed by Kelly, Barnes & Fisher. Click here to see an example of the "missing method ?" of assignment, to build up a depth profile of polytypes in SiC from morphological clues on an X-ray topograph.

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A Brief History of Silicon Carbide - Jim Kelly

A Brief History of X-Ray Diffraction Topography - Jim Kelly

Polytype Coalescence Sandwich Models - Research Results

© Jim Kelly 2006