Uniformity and Reliability of Enhancement-Mode Polycrystalline Indium Oxide Thin Film Transistors Formed by Solid-Phase Crystallization

A bottom-gate thin-film transistor (TFT) with hydrogen-doped polycrystalline indium oxide (poly-InOx:H) channel was fabricated to investigate the uniformity and reliability of the TFT. The carrier density ( ${N}_{\text {e}}\text {)}$ of the poly-InOx:H film markedly decreased after solid-phase crystallization in air at 300°C, and a nondegenerate poly-InOx:H film with ${N}_{\text {e}}$ of ${1}.{7}\times {10} ^{{17}}$ cm $^{-{3}}$ could be achieved. The TFT with a 30-nm-thick poly-InOx:H channel operated in enhancement mode (E-mode) after post-fabrication annealing at more than 300°C. The poly-InOx:H TFT exhibited good short-range uniformities with a field-effect mobility ( $\mu _{\text {FE}}\text {)}$ of $32.0~\pm ~0.39$ ( $3\sigma \text {)}$ cm2/Vs and a threshold voltage ( ${V}_{\text {t}}\text {)}$ of $0.58~\pm ~0.18$ ( $3\sigma \text {)}$ V. Furthermore, no threshold voltage shift was observed under negative gate bias and temperature stress at 60°C for 6,000 s.