Deep center characterization by photo-induced transient spectroscopy

Abstract

We show that photo-induced current transients in semi-insulating GaAs are well fitted by a unique sum of exponentials including the anomalous case, in which one of the exponentials has a negative amplitude. This fitting procedure is proposed as a more reliable method to be used in obtaining the trap emission constant. We also present an analytic solution for the kinetic equations of carriers taking into account the background current and the carrier recapture processes, which have been neglected in the previous approaches. This solution contains a very simple and physically coherent explanation for the appearance of negative peaks in the spectra of photo-induced transient current spectroscopy.