DLTS of recombination centres in semiconductors

Deep-level transient spectroscopy (DLTS) offers a powerful tool for monitoring defects in semiconductors. Conventional DLTS techniques, however, are designed for the observation of traps, i.e., defect levels in the bandgap of the semiconductor which can capture only one type of current carrier. A new version of DLTS (recombination DLTS) which is proposed in this paper permits the observation of recombination centres which are efficient in the capture of both electrons and holes. Recombination DLTS uses a majority-carrier injection pulse in combination with a controlled injection of minority carriers by an optical beam. A defect level which has sizeable capture cross sections for both majority and minority carriers (i.e., a recombination centre) can thus be filled and emptied in a controlled manner, and the level occupation monitored by the amplitude of the majority-carrier peak in the DLTS spectrum.