Abstract
In photoluminescence (PL) spectra of a ZnS–ZnTe superlattice grown on GaAs substrate a multi-band structure with equal energy spacing of about 90 meV has been observed. This multi-band structure is shown to be explainable with a one-dimensional harmonic oscillator model where electrons and holes are confined separately in approximately parabolic potential wells formed by space charges at the p–n heterojunctions. The origin of the PL spectrum is attributed to electron–hole recombinations from electrons being in Boltzmann distribution among levels n=0, 1, 2,… in n-ZnS to the holes at n=0 level in p-ZnTe. However, an appreciably higher electron temperature than the lattice temperature is necessary for explaining the observed spectral shape, although the temperature during decay shows a tendency of cooling down. Thermal quenching of the luminescence as a whole is thought to be due to hole release from the level in ZnTe.
Published Version
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