A study of CVD growth kinetics and morphological evolution of rhenium from ReCl₅

Rhenium was fabricated on molybdenum by chemical vapor deposition (CVD) of ReCl₅ in a cold-wall atmospheric pressure reactor at temperature range of 1000 to 1300°C. To investigate the deposition mechanism, the process was carried out by direct sublimation of ReCl₅ powder instead of the commonly used in-situ chlorination of solid rhenium method to supply the precursor. The effects of deposition temperature, ReCl₅ partial pressure, and molybdenum substrates on deposition velocity, microstructure were investigated. The deposition was under kinetics control and fitted to a 1.5-power relation versus ReCl₅ partial pressure at 1150 to 1250°C. One reaction pathway has been proposed depending on ReCl₅ partial pressure. At deposition temperature below or equal to 1100°C, the reaction between molybdenum and ReCl₅ was calculated and discussed. Evolution of coating microstructure was summarized into a schematic with four typical deposited regions, which provides a simple and efficient way to deposit certain microstructures of rhenium coatings.