Photoluminescence study of carrier collection and recombination in thin GaInAs/InP single quantum wells

Abstract

The photoluminescence (PL) from thin GaInAs/InP single quantum wells (SQWs) grown by atmospheric pressure organometallic vapor phase epitaxy is investigated. The 10-K PL intensity from the SQWs is as much as 25 times stronger than that from approximately 1.5-μm-thick epitaxial GaInAs layers. The underlying PL processes, namely photogeneration of carriers, carrier collection by the well, and recombination in the well, are studied. The photogeneration of carriers in the well is calculated to be negligible compared to that occurring in the InP barriers. In contrast, the quantum-well PL is approximately a factor of 4500 stronger than the barrier PL for all samples at temperatures ranging from 10–300 K. This necessitates rapid and efficient transfer of photogenerated carriers from the barriers into the well. The transfer is investigated by applying a rate equation model relating the barrier and quantum well PL intensities to the lifetimes governing the recombination dynamics in the barriers and in the well. The transfer is calculated to occur within a few picoseconds at 10 K with nearly 100% transfer efficiency. The temperature dependence of the barrier PL spectra shows that the carrier-collection efficiency of the well remains high up to room temperature. The integrated quantum-well PL intensity decreases by approximately two orders of magnitude as the temperature is raised from 10 to 300 K, which is attributed to a decrease of the radiative quantum efficiency of the well. Results of a PL-excitation study suggest that the PL is due to interface- or cluster-localized exciton recombination at 10 K at low excitation intensities. At high temperatures and excitation intensities, the PL spectra show evidence for delocalization and/or dissociation of the excitons.