Multisubband photoluminescence in sawtooth doping superlattices

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Abstract
Photoluminescence spectra on doping superlattices consist of multiple, clearly resolved, interband transitions between quantum-confined states. Not only the ground-state transition is observed, but also higher-energy transitions due to an opposite energy dependence of the oscillator strength and thermal distribution of carriers. Variational solutions of the three lowest states are used to obtain consistent understanding of optical emission spectra in sawtooth doping superlattices. Under higher excitation intensities, the photoluminescence peak energies of the quantum-confined transitions shift to higher energies, and new transitions become observable. The changes of the photoluminescence spectra can be understood on the basis of screening, band filling, and increased carrier temperature at higher excitation intensity.