Conformal growth of copper sulfide thin films on highly textured surface via microreactor-assisted solution deposition

Abstract

In this work, the preparation of copper sulfide (Cu_xS) thin films via microreactor-assisted solution deposition (MASD), consisting of separation of the homogeneous reaction and deposition from the molecular level heterogeneous surface reaction, is demonstrated. A particle-free flux in solution was obtained by adjusting the key process parameters, namely concentration of reactants, reaction temperature, and residence time, resulting in a high-quality film and a high deposition rate (40–100 times higher than that of films deposited by chemical bath deposition). Moreover, the growth of Cu_xS thin films was monitored using an in situ quartz crystal microbalance. We found that the growth rate significantly depends on the heterogeneous temperature and residence time, while limited influence of homogeneous temperature was observed. Furthermore, conformal and dense Cu_xS thin films were deposited on a highly textured Si surface that demonstrates enhanced photon absorption.