Performance improvement of thin-film transistors with In2O3 channel engineering

ABSTRACT Thin-film transistors (TFTs) with bilayer channels were used to improve the field-effect mobility and bias stress stability of the TFTs. Homogeneous structures were fabricated by the combination of a carrier deficient layer made of In2O3 thin film annealed in oxygen atmosphere (InO:O) and an electron injection layer made of In2O3 thin film annealed in air (InO:A). Compared with the InO:A/InO:A TFT with only air annealing, the field-effect mobility of InO:O/ InO:A TFT with two-step annealing process was improved from 0.04 to 5.11 cm2/Vs, the on/off current ratio was ameliorated from 4.6 × 105 to 7.6 × 107 A, while the VTH is decreased from 12.5 to 4.7 V under the positive bias stressing (PBS). It is confirmed that the excessive oxygen vacancies are produced by annealing the thin film in the air. The electrical performance of the InO:O/InO:A TFTs with two-step annealing process is greatly improved due to the formation of a low defect state and high carrier concentration electron transport layer, through the combination of the carrier transport layer and the carrier injection layer. These optimized electrical properties indicate an important step toward achieving transparent, high performance, and low-temperature metal oxides TFTs.