Deep-level transient conductance spectroscopy of high resistivity semiconductors



We describe a deep-level transient-conductance (DLTC) spectrometer for high resistivity semiconductors, which uses a radiofrequency (∼40 MHz) marginal oscillator as conductance detector. The DLTC spectra are generated by periodically filling the deep-level trapping centres by carriers stimulated by a pulsed GaAs laser. Then the trap-emptying conductance's signal process through an exponential Miller correlator as the sample temperature is slowly ramped. A simple capacitive coupling of the samples to the oscillator tank circuit eliminates problems such as unwanted defect annealing and other material changes often associated with the high-temperature techniques necessary for ohmic contact formation. Representative deep-level spectra for CdTe, CdZnTe, HgI and gamma-irradiated Si are given. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)