Defect Engineering in MBE-Grown CdTe Buffer Layers on GaAs (211)B Substrates

W. W. Pan, R. J. Gu, Z. K. Zhang, W. Lei, G. A. Umana-Membreno, D. J. Smith, J. Antoszewski, L. Faraone

Research output: Contribution to journalArticlepeer-review

Abstract

Demand for high-performance HgCdTe infrared detectors with larger array size and lower cost has fuelled the heteroepitaxial growth of HgCdTe on CdTe buffer layers on lattice-mismatched alternative substrates such as Si, Ge, GaAs and GaSb. However, the resulting high threading dislocation (TD) density in HgCdTe/CdTe limits their ultimate application. Herein, strained CdZnTe/CdTe superlattice layers have been used as dislocation filtering layers (DFL) to reduce the TDs in CdTe buffer layers grown on GaAs (211)B substrates (14.4% lattice-mismatch) by molecular beam epitaxy (MBE). Cross-sectional microstructure characterization indicates that the DFLs suppress the propagation of TDs. For optimal Zn content combined with thermal annealing, the DFLs effectively reduce the defect density of the upper-most CdTe layer from low-107 cm−2 to the critical level of below 106 cm−2. In comparison to conventional buffer CdTe layers, the in-plane lattice of the CdTe layers in/near the DFL region is compressively strained, leading to a spread in x-ray double-crystal rocking curve full-width at half-maximum values but better in-plane lattice-matching with HgCdTe. The combined advantages of lower dislocation density and better lattice-matching with HgCdTe indicate that the DFL approach is a promising path towards achieving heteroepitaxy of high-quality HgCdTe on large-area lattice-mismatched substrates for fabricating next-generation infrared detectors.

Original languageEnglish (US)
JournalJournal of Electronic Materials
DOIs
StateAccepted/In press - 2022

Keywords

  • alternative substrates
  • CdTe
  • dislocation filters
  • etch pit density
  • HgCdTe

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry

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