Fabrication and Characterization of High-Mobility Solution-Based Chalcogenide Thin-Film Transistors

摘要

We report device and material considerations for the fabrication of high-mobility thin-film transistors (TFTs) compatible with large-area and inexpensive processes. In particular, this paper reports photolithographically defined n-type TFTs (n-TFTs) based on cadmium sulfide (CdS) films deposited using solution-based techniques. The integration process consists of four mask levels with a maximum processing temperature of 100 $^{circ}hbox{C}$. The TFT performance was analyzed in terms of the CdS semiconductor thickness and as a function of postdeposition annealing in a reducing ambient. The $I_{rm on}/I_{rm off}$ ratios are $sim!! hbox{10}^{7}$ with field-effect mobilities of $ sim$5.3 and $sim!hbox{4.7} hbox{cm}^{2}/hbox{V}cdot hbox{s}$ for Al and Au source–drain contacts, respectively, using 70 nm of CdS. Transmission electron microscopy and electron energy loss spectroscopy were used to analyze the CdS–metal interfaces.