Project Summary Infrared (IR) detectors based on mercury-cadmium-telluride (MCT) continue to be of central importance for sensing applications. However, the reliable growth of high quality MCT on large-area, low-cost substrates represents a major stumbling block to further developments, and there is much ongoing interest and active research aimed at overcoming existing limitations. In this proposed program of work, advanced electron microscopy and analytical methods will be used, in close collaboration with growth studies being carried out elsewhere, to achieve substantial improvements in Hg-based materials for IR detector applications. Routine techniques for characterization will include diffraction contrast and high-resolution imaging, nanoprobe spectroscopy, and convergent-beam electron diffraction. In addition, aberration-corrected electron microscopy and spectrum imaging will be used to probe interfacial structure and chemistry at the atomic scale. The research program will target several inter-related topics, although the major focus will be to address the reduction of growth defects in MCT films grown by molecular beam epitaxy on alternative composite substrates based on silicon, gallium arsenide and/or germanium with Zn(Se)Te (or Cd(Se)Te) intermediary buffer layers. The importance of lattice mismatch, valence mismatch, and thermal expansion in causing threading dislocations and other growth defects will be assessed, and the possibly detrimental role of chemical contaminants at growth defects and interfaces will be determined. Attention will also be directed towards identifying the Burgers vector of predominant dislocations and strategies for reducing defect densities. The growth of HgCdSe, which is another promising IR detector material, will also be investigated, with particular emphasis again on defect reduction as well as establishing reliable etch-pit-density measurements. The eventual outcome of these closely collaborative studies should be improved materials quality and enhanced IR detector performance.
|Effective start/end date||8/1/13 → 11/30/16|
- DOD-ARMY-ARL: Army Research Office (ARO): $371,622.00