Systematically-optimized charge transport properties in cumulatively solution-coated zinc tin oxide and applications for complementary inverter circuits combining organic p-type transistors

Zinc-tin-oxide (ZTO) is considered as a promising alternative thin-film semiconductors due to its merits of Earthabundant materials, non-toxicity, and solution-processable low-cost manufacturing. However, there is still insufficient effort to implement a ZTO-based practical applications such as integrated circuits due to the lack of desirable switching behavior for circuit operation. In this context, we systematically investigate a solution processed ZTO film through a comprehensive analysis including scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission line method (TLM), and X-ray photoelectron spectroscopy (XPS). We also fabricate the synthesized ZTO-based transistors, and characteristics of the transistors are evaluated depending on annealing temperature and number of coatings. Through the systematic investigation, this study obtains the suitable turn-on voltage of VTo = 0.15 V as well as uniform charge transport property of 2.14 cm(2)/V.s +/- 5.14%. Furthermore, we apply the ZTO transistor optimized for the circuit to the complementary inverter logic, and the measured inverter circuit provides an excellent voltage gain of 141.18 V/V and improved noise margin as high as 71.4% of half the supply voltage.