Low-Temperature Solution-Processed Amorphous Indium Tin Oxide Field-Effect Transistors

Amorphous indium tin oxide (ITO)-based thin-film transistors (TFTs) were fabricated on various dielectrics [SiO2 and self-assembled nanodielectrics (SANDs)] by spin-coating an ITO film precursor solution consisting of InCl3 and SnCl4 as the sources of In3+ and Sn4+, respectively, methoxyethanol (solvent), and ethanolamine (base). These films can be annealed at temperatures T-a <= 250 degrees C and afford devices with excellent electrical characteristics. The optimized [In3+]/[In3+ + Sn4+] molar ratio (0.7) and annealing temperature (T-a = 250 degrees C) afford TFTs exhibiting electron mobilities of similar to 2 and similar to 10-20 cm(2) V-1 s(-1) with SiO2 and SAND, respectively, as the gate dielectric. Remarkably, ITO TFTs processed at 220 degrees C still exhibit electron mobilities of > 0.2 cm(2) V-1 s(-1), which is encouraging for processing on plastic substrates.