Space-charge effects in type-II strained layer superlattices

I.V. Bradley, J.P. Creasey, K. P. O'Donnell

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


The low-temperature photoluminescence (PL) spectra of a range of CdS-CdSe and CdS-ZnSe type-II superlattices was measured under both cw and quasi-cw excitation over the excitation range from mW cm-2 to MW cm-2. In all cases, a single PL band due to the recombination of separated electrons and holes in the type-II bandstructure was observed. As the excitation density increases from a low value, the PL peak shifts logarithmically towards the blue. Total shifts of up to 200 meV for a CdS-CdSe sample of 10 nm period are observed, with a corresponding shift-factor of 30 meV per decade of excitation density. The shift factor increases in a regular fashion with the superlattice period. A comparison with the literature shows that a logarithmic dependance of the blue shift with increasing excitation density appears to be a universal feature of type-II SL, even in the absence of strain.

Original languageEnglish
Pages (from-to)728-731
Number of pages4
JournalJournal of Crystal Growth
Publication statusPublished - 2 Feb 1998


  • superlattices
  • photoluminescence
  • strained layer superlattice


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