Fabrication of IR transparent zinc sulphide plate by chemical vapour deposition (CVD)

Abstract

Recent developments in Chemical Vapour Deposition (CVD) processing with its inherent advantages provide a feasible route for producing high quality optically transparent ceramic materials. CVD process feasibility of the reaction between Zn and H₂S in obtaining optical quality ZnS deposits are evaluated with respect to the free energy requirements. Rayleigh number (R_a) of 10⁶corresponding to laminar flow indicated optimum flow velocities during CVD processing. Deposits show desirable thickness uniformity of 0.55% per cm and were found to have a phase pure ZnS XRD phase. EBSD patterns exhibited a highly oriented columnar ZnS grains and the specimens have shown the theoretical transmission values in the IR ranges.