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Localization and band-gap pinning in semiconductor superlattices with layer-thickness fluctuations

K. A. Mader·A. Zunger
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Abstract

We consider (AlAs)_n/(GaAs)_n superlattices with random thickness fluctuations Delta-n around the nominal period n. Using three-dimensional pseudopotential plane-wave band theory, we show that (i) any amount Delta-n/n of thickness fluctuations leads to band-edge wavefunction localization, (ii) for small Delta-n/n the SL band gap is pinned at the gap level produced by a single layer with ``wrong'' thickness n + Delta-n, (iii) the bound states due to monolayer thickness fluctuations lead to significant band-gap reductions, (iv) <001> AlAs/GaAs SL's with monolayer thickness fluctuations have a direct band gap, while the ideal <001> SL's are indirect for n<4.

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K. A. Mader, A. Zunger. 1995-07-27. Localization and band-gap pinning in semiconductor superlattices with layer-thickness fluctuations. https://doi.org/10.1209/0295-5075%2F31%2F2%2F008

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