Combinatorial Liquid Flow Deposition of PbS Semiconductor Thin Films

Chemical bath deposition (CBD) and its variant liquid flow deposition (LFD) are important and straightforward solution-based methods, and yet they rely on time- and resource-consuming serial experiments. In this work, we introduce a combinatorial approach for LFD (CLFD). A custom-made, open-top continuous flow reactor maintained uniform and constant deposition conditions, facilitating combinatorial investigation of deposition time by drawing the substrate using a dip coater. We demonstrate the use of CLFD for the deposition of PbS thin films, resulting in a discrete library of five deposition times (15-55 min) on a single GaAs (100) substrate. X-ray diffraction and scanning electron microscopy confirmed the formation of high-quality PbS films with a well-defined orientation and film thickness up to 6 microns at longer deposition times. The deposition rate, material quality, and growth mechanism of the films were similar to those obtained using CBD and LFD. The CLFD approach facilitates rapid parameter optimization, as demonstrated for a range of pH values (13.8-14.3) and two temperatures (25 and 30 °C). Thus, CLFD can potentially serve as a universal method for cost-effective research and optimization of solution-deposited thin films.