Chemical bath deposition of CdS channel layer for fabrication of low temperature-processed thin-film-transistors

∼66 nm thick CdS film with a hexagonal structure was uniformly generated via a low temperature-processed chemical bath deposition at 80 °C using a complexing agent of ethylenediaminetetraacetic acid and its crystal structure, surface morphology, optical transmittance, and Raman scattering property were measured. Grown CdS film was used as a channel layer for the fabrication of bottom-gate, top-contact thin-film-transistor (TFT). The TFT device with 60 °C-dried channel layer exhibited a poor electrical performance of on-to-off drain current ratio (Ion/Ioff) of 5.1 × 103 and saturated channel mobility (μsat) of 0.10 cm2/Vs. However, upon annealing at 350 °C, substantially improved electrical characteristics resulted, showing Ion/Ioff of 5.9 × 107 and μsat of 5.07 cm2/Vs. Furthermore, CdS channel layer was chemically deposited in an identical way on a transparent substrate of SiNx/ITO/glass as part of transparent TFT fabrication, resulting in Ion/Ioff of 5.8 × 107 and μsat of 2.50 cm2/Vs.