Excitons and biexcitons in InGaN quantum dot like localization centers

S. Amloy, K. F. Karlsson, M. O. Eriksson, J. Palisaitis, P. O.A. Persson, Y. T. Chen, K. H. Chen, H. C. Hsu, C. L. Hsiao, L. C. Chen, P. O. Holtz

研究成果: Article同行評審

6 引文 斯高帕斯(Scopus)

摘要

Indium segregation in a narrow InGaN single quantum well creates quantum dot (QD) like exciton localization centers. Cross-section transmission electron microscopy reveals varying shapes and lateral sizes in the range ∼1-5 nm of the QD-like features, while scanning near field optical microscopy demonstrates a highly inhomogeneous spatial distribution of optically active individual localization centers. Microphotoluminescence spectroscopy confirms the spectrally inhomogeneous distribution of localization centers, in which the exciton and the biexciton related emissions from single centers of varying geometry could be identified by means of excitation power dependencies. Interestingly, the biexciton binding energy (Ebxx) was found to vary from center to center, between 3 to -22 meV, in correlation with the exciton emission energy. Negative binding energies are only justified by a three-dimensional quantum confinement, which confirms QD-like properties of the localization centers. The observed energy correlation is proposed to be understood as variations of the lateral extension of the confinement potential, which would yield smaller values of Ebxx for reduced lateral extension and higher exciton emission energy. The proposed relation between lateral extension and Ebxx is further supported by the exciton and the biexciton recombination lifetimes of a single QD, which suggest a lateral extension of merely ∼3 nm for a QD with strongly negative Ebxx=-15.5 meV.

原文English
文章編號495702
期刊Nanotechnology
25
發行號49
DOIs
出版狀態Published - 2014 12月 12

All Science Journal Classification (ASJC) codes

  • 生物工程
  • 一般化學
  • 一般材料科學
  • 材料力學
  • 機械工業
  • 電氣與電子工程

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