Observation of very efficient cold exciton emission due to the first excited subband state in GaAs/AlxGa1-xAs quantum wells

摘要

Strong emission due to cold exciton formation associated with the first excited (n = 2) subband state in a GaAs quantum well is observed by spatially resolved cathodoluminescence spectroscopy, measured on the cleaved edge of the heterostructure. Origins of the enhanced (n = 2) emission are discussed based on the spatially selective carrier generation and capture and the parity-forbidden relaxation pathway of cold (n = 2) excitons into the ground exciton state.