Characterization of impurities in GaInNAs pn junctions from capacitance transient spectroscopy

Difficulties and their solutions found during the determination of parameters of impurities in thin GalnNAs solar cells, by means of spectroscopic capacitance measurements, are presented in this work. The parameters of impurities present in the GalnNAs pn junctions are determined by an iterative method, comparing experimental capacitance transients with calculated ones. The results disagree with the ones obtained by applying the classical expressions associated to the capacitance deep level transient spectroscopy (DLTS). The parameters of the centers are used to determine the hole diffusion lengths in the semiconductor. The agreement between the hole diffusion lengths obtained with our method and results found in literature means that DLTS must be used with care when determining recombination centers in thin pn junctions. An expression to be included in the DLTS technique, that incorporates these effects, is proposed.