Fabrication of ZnSX IR Windows by Physical Vapor Transport Technique.
Final technical rept.15 Nov 73-15 Nov 75,
HUGHES RESEARCH LABS MALIBU CALIF
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We conducted a developmental investigation directed toward the fabrication of ZnSe, ZnS and mixed crystal ZnS1-xSex windows by a physical vapor transport PVT technique. The PVT process utilizes the vapor-solid relationship of the II-VI compounds to transport material from a solid compact source at an elevated temperature approximately 1000 C for ZnSe to a uniformly heated substrate at a highly lower temperature 2 to 5 C lower than source via gaseous phase under conditions of dynamic vacuum which prevent pressure buildup inside the chamber, i.e., maintains the total pressure at a minimum P min. Primarily most of our effort went into development of a laboratory scale up to 3.25 in. diameter apparatus using ZnSe. In this size, we also studied some mixed crystal specimens of composition Zn0.9 using an intimate mechanical mixture of 83 at . ZnS, 17 at. ZnSe as the source material the final sample showed uniformity both axially and radially within the analytical limits of the electron microprobe or -1. This composition showed a marked decrease in the 10 microns absorption typically shown by pure ZnS indicating the possibility of using sulfide-rich mixed-crystal compositions for application as rain erosion-resistant common-aperture airborne windows in the multispectral range 0.5 to 14 microns.
- Physical Chemistry
- Infrared Detection and Detectors