Impact of Extended Defects on Recombination in CdTe Heterostructures Grown by Molecular Beam Epitaxy

Katherine Zaunbrecher, Darius Kuciauskas, Patricia Dippo, Teresa Barnes, Craig Swartz, Madhavie Edirisooriya, Olanrewaju Ogedengbe, Sandeep Sohal, Bobby Hancock, Elizabeth LeBlanc, Pathiraja Jayathilaka, Thomas Myers

Research output: Contribution to journalArticlepeer-review

17 Scopus Citations

Abstract

Heterostructures with CdTe and CdTe1-xSex (x ∼ 0.01) absorbers between two wider-band-gap Cd1-xMgxTe barriers (x ∼ 0.25-0.3) were grown by molecular beam epitaxy to study carrier generation and recombination in bulk materials with passivated interfaces. Using a combination of confocal photoluminescence (PL), time-resolved PL, and low-temperature PL emission spectroscopy, two extended defect types were identified and the impact of these defects on charge-carrier recombination was analyzed. The dominant defects identified by confocal PL were dislocations in samples grown on (211)B CdTe substrates and crystallographic twinning-related defects in samples on (100)-oriented InSb substrates. Low-temperature PL shows that twin-related defects have a zero-phonon energy of 1.460 eV and a Huang-Rhys factor of 1.50, while dislocation-dominated samples have a 1.473-eV zero-phonon energy and a Huang-Rhys factor of 1.22. The charge carrier diffusion length near both types of defects is ∼6 μm, suggesting that recombination is limited by diffusion dynamics. For heterostructures with a low concentration of extended defects, the bulk lifetime was determined to be 2.2 μs with an interface recombination velocity of 160 cm/s and an estimated radiative lifetime of 91 μs.

Original languageAmerican English
Article numberArticle No. 091904
Pages (from-to)19446-19455
Number of pages10
JournalApplied Physics Letters
Volume109
Issue number9
DOIs
StatePublished - 29 Aug 2016

Bibliographical note

Publisher Copyright:
© 2016 Author(s).

NREL Publication Number

  • NREL/JA-5K00-67149

Keywords

  • diffusion
  • epitaxy
  • II-VI semiconductors
  • III-V semiconductors
  • photoluminescence

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