Research on HgCdTe Fabrication Using Directed Energy Techniques
Semiannual technical rept.
SPIRE CORP BEDFORD MA
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The goal of this research is to produce large-area, thin-film, single crystal HgCdTe material for infrared detectors. The successful approach is to 1 evaporate CdTe in an enclosed furnace on insulating crystalline substrates hot wall epitaxy, 2 melt a thin surficial layer by pulsed electron beam irradiation to improve morphology, and 3 convert to HgCdTe by evaporation and diffusion at constant temperature. The final result is a single crystal film of Hg1-xCdxTe, 30 microns thick and 0.5 inch square, with a compositional variation of x less than or - 0.0007. Films of up to 20 microns thick, 1 inch o.d., single crystal but twinned CdTe were produced by the first process. These faceted films were smoothed without change of surface stoichiometry or structure by the second process. Evaporation of HgTe at less 0.5 atm Hg overpressure onto the CdTe film produced the final result on mica or quartz substrates. Electron mobility at 77 K was as high as 1.5 x 100,000 sq cmV-s in the final samples.
- Solid State Physics