Environmentally and Electrically Stable Sol-Gel-Deposited SnO 2 Thin-Film Transistors with Controlled Passivation Layer Diffusion Penetration Depth That Minimizes Mobility Degradation.

This study examines the effect of the annealing time of the Y 2 O 3 passivation layer on the electrical performances and bias stabilities of sol-gel-deposited SnO 2 thin-film transistors (TFTs). The environmental stabilities of SnO 2 TFTs were examined. After optimizing the Y 2 O 3 passivation layers in SnO 2 TFTs, the field-effect mobility was 7.59 cm 2 /V•s, the V TH was 9.16 V, the subthreshold swing (SS) was 0.88 V/decade, and the on/off-current ratio was approximately 1 × 10 8 . V TH shifts were only -0.18 and +0.06 V under negative and positive bias stresses, respectively. The SnO 2 channel layer thickness and oxygen-vacancy concentration in SnO 2 , which determine the carrier concentration, were successfully tuned by controlling the annealing time of the Y 2 O 3 passivation layers. An extremely thin Y 2 O 3 passivation layer effectively blocked external molecules, thus affecting the device performance. The electrical performance was maximized in SnO 2 TFTs using a 15 min-annealed Y 2 O 3 passivation layer. In this TFT, the field-effect mobility was maximally retained and the bias and environmental stabilities were sustained over 90 days of air exposure.