Deep center characterization by optically-controlled paramagnetic resonance in AgGaS2

A new method for deep center characterization, based on the analysis of their EPR signal intensity under a dual beam optical excitation, is presented. It allows the determination of some important physical parameters of a deep center, like its photoionization energy and its optical capture cross section. An application of this method is given by the study of two transition metal-induced defects in the chalcopyrite compound AgGaS2. The basic interest of this new technique rests in the fact that it yields a quantitative value of parameters useful in deep level theory and that it may help to bridge the gap between physically assessed centers and their chemical identification by regular EPR technique.