Transformation kinetics of an intrinsic bistable defect in damaged silicon

Abstract

The positions of the electronic levels of an intrinsic bistable defect have been measured using deep level transient spectroscopy (DLTS) in n- and p-type damaged silicon bipolar transistor diodes after minority carrier injection and thermal annealing. The kinetic rates observed during conversion of this defect have been determined using both DLTS and transistor gain measurements on devices irradiated with electrons and neutrons. First order conversion kinetics are observed during both injection and thermal annealing of this defect in electron damaged transistors, but more complicated, stretched-out kinetics are seen in neutron irradiated devices. The latter behavior can be successfully modeled as a small spread in the energy barriers for atomic displacements of this defect probably due to strain or electrostatic variations expected in damage clusters. The measured injection bias dependence of the recombination-driven transition to the bistable state of this defect is unlike that seen for generation-recombination currents at deep trap levels, but it is consistent with Shockley—Read–Hall predictions for recombination at shallow states. This latter behavior is expected from the lone shallow peak seen in DLTS measurements of the stable state of this center. Some comparisons of the present results with existing models of this defect are made.