Vapor phase epitaxy of PbS single-crystal films on water-soluble substrates and application to photodetectors

Lead sulfide (PbS), a typical functional semiconductor material, has attracted serious attention due to its great potential in optoelectronics applications. However, controllable growth of PbS single-crystal film still remains a great challenge. Here, we report heteroepitaxial growth of large-scale highly crystalline PbS films on alkali salt (NaCl and KCl) substrates via chemical vapor deposition (CVD). Structural characterizations demonstrate that the as-grown PbS films exhibit an atomically sharp interface with the underlying substrates. The epitaxial relationships between the epilayers and substrates were determined to be PbS (100)//NaCl (100) or KCl (100), PbS [010]//NaCl [010] or KCl [010]. Owing to the high solubility of alkali salt, the epitaxial PbS films can be rapidly released from the underlying substrates and transferred to other substrates of interest while maintaining good integrity and crystallinity, the process of which is particularly attractive in the fields of electronics and optoelectronics. Furthermore, photodetectors based on the transferred PbS films were fabricated, exhibiting a high photoresponsivity of 7.5 A/W, a detectivity of 1.44 × 10¹² Jones, and a rapid response time of approximately 0.25 s. This work sheds light on the batch production, green transfer, and optoelectronic application of PbS films.