Origin of localized states in zinc-blende ZnCdSe thin films and the influence on carrier relaxation of self-assembled ZnTe/ZnCdSe quantum dots

Ling Lee*, Yue Ru Dai, Chu Shou Yang, Wen Chung Fan, Wu-Ching Chou

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

This study discovered the origin of deep level emission in zinc-blende ZnCdSe thin films grown by molecular beam epitaxy, in which a localization behavior was noticed. Pronounced deep level emission observed in films grown under a VI/II ratio of 1.74 (Se-accumulated regime) could be suppressed by a lower VI/II ratio of 1.04 (intermediate regime) and 0.74 (metal-rich regime). Hence the localized states could be correlated to excess selenium accumulated at the growth surface. The localized states also influence the carrier relaxation process of self-assembled ZnTe quantum dots embedded in a ZnCdSe matrix. Once quantum dots surmount the wetting layer, localized electrons in the capping layer dominate the type-II transition and exhibit size-independent lifetimes.

Original languageEnglish
Pages (from-to)392-396
Number of pages5
JournalJournal of Alloys and Compounds
Volume632
DOIs
StatePublished - 25 May 2015

Keywords

  • Nanostructured materials
  • Optical properties
  • Semiconductors
  • Time-resolved optical spectroscopies
  • Vapor deposition

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