Effects of Carrier Concentration, Indium Content, and Crystallinity on the Electrical Properties of Indium-Tin-Zinc-Oxide Thin-Film Transistors

We report the effects of carrier concentration (N-CH), indium (In) content, and crystallinity (X-c) on the electrical properties of indium-tin-zinc-oxide (ITZO) thin-film transistors (TFTs). The ITZO TFT with the lowest N-CH, In content, and amorphous phase at the optimized oxygen flow rate has high field-effect mobility (mu(FE)) of 37.2 cm(2)/V.s, high ON/OFF current ratio (I-ON/I-OFF) of similar to 1 x 10(7), and low subthreshold swing (S.S) of 0.93. With increasing N-CH, In content, and X-c, mu(FE), I-ON/ IOFF, and S.S surprisingly degraded to 14.4 cm(2)/V . s, similar to 4 x 10(4), and 4.01, respectively. Our high ITZO TFTs with mu(FE) of 37.2 cm(2)/V.s, obtained thorough control of the N-CH, In content, and X-c, was suitable for application to next generation ultrahigh resolution displays as well as high frame rate displays.