A Facile Solution-Deposited Approach to Fabricate High-Mobility CdS Thin Film Transistors

Cadmium sulfide (CdS) has a wide direct band gap of 2.4 eV and a high single-crystal mobility over 200 cm 2 /V s, which makes it appealing for high-performance thin-film transistor (TFT) fabrication. The chemical bath deposition (CBD) is the most common method to deposit CdS thin film. However, CBD method is time-consuming and will generate large amounts of environmentally harmful wastes. In this work, we demonstrate a relatively safe, facile, versatile and low-cost molecular-based precursor solution approach to deposit CdS thin film as the channel layer in TFTs via spin-coating. To find out the best annealing conditions, the impacts of the annealing temperature and time on the electrical properties of CdS TFTs are studied. It is found that the CdS TFTs annealed at 450 °C for 30 min exhibit the maximum linear field-effect mobility (μ lin ) of 52.0 cm 2 /V s, the on/off current ratio of >10 6 and the minimum subthreshold swing ( SS ) of 0.35 V/dec, which illustrates that the molecular-based precursor solution approach is promising for high-performance CdS TFTs.