A defect characterization method is presented that promises to provide improved defect detection sensitivity. The new technique involves the use of current-source biasing of a pn diode. Under current-source bias the junction voltage is transient, whereas standard deep level transient spectroscopy typically involves voltage-source bias with either capacitance or current transients. Computer simulations predict voltage transients of 5 mV from samples that, under identical trap capture and emission conditions, yield capacitance and current transients of only 0.2 fF and 0.7 pA. The new approach can tolerate large leakage currents, and the voltage transient amplitude is independent of device area.