A new approach to trap parameter extraction from temperature-induced changes in photocurrent transients following switching light on and off is proposed. The method is based on using a correlation procedure and an assumed weighting function to transform experimental data into two-dimensional spectra in coordinates of temperature and thermal emission rate of charge carriers. The folds at the surface formed due to the presence of traps are fitted with two-dimensional approximation functions. As a result the trap activation energy and capture cross-section are obtained. The new approach is exemplified by determination of parameters of the centre A (vacancy-oxygen complex) in neutron irradiated silicon. A good agreement between the trap parameters obtained from the photocurrent transients after switching light on and off has been found. (C) 2002 Elsevier Science Ltd. All rights reserved.