Self-aligned coplanar amorphous indium zinc oxide thin-film transistors with high performance

• Highly-stable high-performance self-aligned coplanar a-IZO TFTs.
• Self-aligned structure with contact doping and active-layer plasma treatment.
• μFE = 24.4 cm2 V−1 s−1, subthreshold slope = 180 mV/dec, and on/off ratio > 109.
• Intrinsic field-effect mobility of 15.05/13.28 cm2 V−1 s−1 (linear/saturation mode).
• ΔVTH (PBTIS/NBTIS) < ±0.7 V after 11,000 s.

Self-aligned coplanar amorphous indium zinc oxide thin-film transistors (a-IZO TFTs) were fabricated. The a-IZO TFTs had a field-effect mobility of μFE = 24.4 cm2 V−1 s−1, a subthreshold slope of 180 mV/dec, and an on/off ratio of 109. As the channel length decreased, the threshold voltage VTH shifted to more negative voltages, and μFE increased due to the diffused carriers from the contact regions. The intrinsic field-effect mobility was estimated to be 15.05 cm2 V−1 s−1 in the linear mode and 13.28 cm2 V−1 s−1 in saturation mode. Under positive/negative bias–temperature–illumination stress, the shift in VTH was less than ±0.7 V after 11,000 s.