Molecular beam epitaxial re-growth of CdTe, CdTe/CdMgTe and CdTe/CdZnTe double heterostructures on CdTe/InSb(1 0 0) substrates with As cap

Shahram Seyedmohammadi, Michael J. DiNezza, Shi Liu, Paul King, Elizabeth G. LeBlanc, Xin Hao Zhao, Calli Campbell, Thomas H. Myers, Yong-Hang Zhang, Roger J. Malik

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Molecular beam epitaxial growth on CdTe substrates is challenging since the CdTe film crystalline and optical quality is limited by residual defects including threading dislocations and stacking faults. This remains an obstacle in spite of exhausting variables including pre-growth substrate preparation as well as epitaxial growth conditions including thermal oxide desorption, growth temperature, and II/VI flux ratios. We propose a new technique to re-grow structures with low defect densities and high optical and structural quality on InSb substrates. The "CdTe virtual wafer" is made by growing a thin CdTe film on an InSb(1 0 0) substrate which is then covered with a thin As cap layer to prevent oxidation of the CdTe surface. The As cap can be removed by thermal desorption at about 300 C leaving a clean CdTe surface for subsequent epitaxial growth. This method eliminates the need for chemical etching of CdTe substrates which has been found to lead to an atomically rough surface with residual Carbon and Oxygen contamination. XRD and SEM characterization show a smooth transition from the buffer CdTe to re-grown CdTe layer with identical crystalline quality as for virtual wafer. Steady-state PL and time-resolved PL from CdTe/CdMgTe double heterostructures show substantial improvement in luminescence intensity and carrier lifetime comparable to values for identical samples grown without exposure to atmosphere. We will also report on CdTe/CdZnTe double heterostructures grown on virtual wafers compared to identical structures on conventional CdTe(2 1 1)B substrates.

Original languageEnglish (US)
Pages (from-to)181-185
Number of pages5
JournalJournal of Crystal Growth
Volume425
DOIs
StatePublished - Jun 20 2015

Keywords

  • A1. Defects
  • A1. Desorption
  • A1. Substrates
  • A3. Molecular beam epitaxy
  • B2. Semiconducting II-VI materials
  • B3. Solar cells

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Inorganic Chemistry
  • Materials Chemistry

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    Seyedmohammadi, S., DiNezza, M. J., Liu, S., King, P., LeBlanc, E. G., Zhao, X. H., Campbell, C., Myers, T. H., Zhang, Y-H., & Malik, R. J. (2015). Molecular beam epitaxial re-growth of CdTe, CdTe/CdMgTe and CdTe/CdZnTe double heterostructures on CdTe/InSb(1 0 0) substrates with As cap. Journal of Crystal Growth, 425, 181-185. https://doi.org/10.1016/j.jcrysgro.2015.02.055