John Steeds

My past research has been based largely on transmission electron microscopy (TEM) and (convergent beam) electron diffraction. However, I have recently embarked on a completely new activity concerned with the study of point defects and their complexes in wide-band-gap semiconductors, such as silicon carbide, diamond, and cubic boron carbide. I aim to understand, exploit, and develop the extremely sensitive method of low-temperature (~7K) photoluminescence microscopy for non-destructive evaluation and identification of defects in these materials. Considerable international and national collaboration is involved. The defects may be grown-in or created by energy-selected irradiation of specimens in a specially adapted 300 kV TEM. The materials are of considerable interest for future applications in high-power, high-temperature, and high-frequency electronics and also for quantum information processing.

The picture above is a cathodoluminescence image of a cross-section through a single crystal diamond film grown by chemical vapour deposition and annealed at 1900C.