Microreactor for High-Yield Chemical Bath Deposition of Semiconductor Nanowires: ZnO Nanowire Case Study

We report on the design of a batch microreactor for depositing oxide and chalcogenide nanowires and thin films onto a substrate from solution, and we demonstrate its utility using ZnO nanowire deposition as a case study. A contact-heated substrate forms one wall of a submillimeter reaction channel, and the short mass-transport length results in high-yield deposition on the substrate with minimal loss to precipitation or deposition on other unheated reactor walls. The microreactor’s low thermal mass enables rapid heating, which reduces the induction time and increases the deposition rate. The microreactor was used to grow dense arrays of well-aligned single-crystal ZnO nanowires with diameters of 80−100 nm and yields of 35%−50%. Deposition rates are faster, yields are an order of magnitude higher, and ZnO defect densities are equivalent to those using a conventional chemical bath deposition reactor with the same chemistry. The species that limit deposition rates are identified.