Experimental identification of the doping deactivation mechanism in semiconductors: Application to nitrogen in ZnS_0.06Se_0.94

We show that quantitative information on the electrical deactivation of doping can be obtained by combining the results of positron annihilation, secondary ion-mass spectrometry, and capacitance-voltage measurements. By applying this method to study the N doping of ZnS_0.06Se_0.94, we can conclude that the fraction of electrically inactive nitrogen may vary from 0% to 80%, depending strongly on the growth conditions. About 40% of the electrically active N exist in the isolated acceptor configuration NSe^- and another 40% is bound to compensating donors, most probably to (ZniNSe)¹⁺ and (V_SeN_Se)¹⁺ pairs. Typically 20% forms negative (V_SeN_Se)^1- complexes with the Se vacancy.