The potentialities of photo-induced transient spectroscopy in terms of the investigation of defect centres in wide-band-gap semiconductors were presented. An experimental system dedicated to measurements of the photocurrent transients at 20 to 800K was described and a new approach to extraction of trap parameters from the photocurrent relaxation waveforms recorded in a selected temperature range was presented. The approach was based on the two-dimensional analysis of the waveforms as a function of time and temperature using the correlation procedure. As a result, three-dimensional images showing the temperature changes of the emission rate for detected defect centres were produced and a neural network method was applied to determine the parameters of defect centres. The new approach was exemplified by studies of defect centres in high-resistivity GaN:Mg and semi-insulating 6H-SiC:V.

Photoinduced Transient Spectroscopy of Defect Centers in GaN and SiC. P.Kamiński, R.Kozłowski, M.Kozubal, J.Żelazko, M.Miczuga, M.Pawłowski: Semiconductors, 2007, 41[4], 414-20