MOCVD ZnS: Mn films: Crystal structure and defect microstructure as a function of the growth parameters

Kathleen A. Dunn*, Katharine Dovidenko, Anna W. Topol, Gajendra S. Shekhawat, Robert E. Geer, Alain E. Kaloyeros

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

Abstract

Thin film electroluminescent devices employing zinc sulfide doped with manganese are extensively used for applications in which the weight, brightness and mechanical robustness requirements preclude the use of other types of displays such as cathode ray tubes or liquid crystal displays. The physical, optical and electrical properties of phosphors such as ZnS:Mn can often depend strongly on microstructure, which in turn depends on the growth and processing of the film. For this study, ZnS:Mn layers were fabricated by metalorganic chemical vapor deposition (MOCVD) in the 250°-500°C range on an Al2TiO/In2SnO5/glass stack. Selected samples were then subjected to a post-deposition anneal in H2S/Ar at 700°C for up to 4 hours. The microstructure of the ZnS:Mn films was examined by Transmission Electron Microscopy (TEM). For all growth and annealing conditions, the films consisted of columnar grains whose column axis was parallel to the growth direction, and which widened laterally through the thickness of the films. For the as-deposited films, the crystal structure was found to be predominantly 2H structure, with the 8H polytype being identified in the low-temperature ZnS:Mn films. The 700°C post-deposition annealing was found to initiate a solid state transformation to the cubic (3C) ZnS crystal structure. All films contained high densities of stacking faults and microtwins, whose role in the 2H-3C transformation is discussed. Also discussed are initial Ultrasonic Force Microscopy (UFM) results which suggest a correlation between the defect microstructure and the elastic response of the material.

Original languageEnglish (US)
Pages (from-to)41-46
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Volume695
StatePublished - Jan 1 2002
EventThin Films: Stresses and Mechanical Properties IX - Boston, MA, United States
Duration: Nov 26 2001Nov 30 2001

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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