Deviation of Time-Resolved Luminescence Dynamics in MWIR Semiconductor Materials from Carrier Recombination Theory Predictions

摘要

Time resolved luminescence spectroscopy was used to characterize luminescence decay curves for a bulk InAs sample and an InAsSb type-I quantum- well sample over the first 3ns following excitation. The luminescence decay curves were then converted to carrier densities and used to find recombination coefficients that provided the least-squared-error solution of the rate equation describing carrier recombination. Recombination coefficients describing Shockley Read-Hall (A(sub SRH)) radiative (B(sub rad)) and Anger (C(sub Aug)) recombination were determined at two different temperatures and four excitation powers, then analyzed for consistency and physical significance. For all of the resulting least squares fits a minimum of one recombination coefficient was negative. While this could be explained in terms of unconfined carriers in the quantum structure the lack of a trend in the parameters with excitation power indicates that this has not the sole contributing factor. No explanation for this behavior could be formulated for the bulk InAs sample. As an alternative approach luminescence decay curves were directly analyzed to evaluate the possibility that the anomalous behavior was an artifact of the initial luminescence-to- carrier density mapping. Again the least squares fit resulted in negative coefficients. Furthermore when the parameters were constrained to be positive the best fit was significantly worse than the unconstrained case. This indicated that negative parameters were not simply an artifact of noise in the data.