0.6V Threshold Voltage Thin Film Transistors With Solution Processable Indium Oxide (In2O3) Channel and Anodized High- \kappa Al2O3 Dielectric

• Published in: IEEE electron device letters 2019-07, Vol.40 (7), p.1112-1115
• Main Authors: Bhalerao, Sagar R., Lupo, Donald, Zangiabadi, Amirali, Kymissis, Ioannis, Leppaniemi, Jaakko, Alastalo, Ari, Berger, Paul R.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; anodization; Dielectrics; Electron traps; Indium; indium oxide (In₂O₃); interface state density; Logic gates; low voltage; Metal oxide semiconductors; solution processing; TFT; Thin film transistors
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2019.2918492

Low-voltage operation and low processing temperature of metal oxide transistors remain a challenge. Commonly metal oxide transistors are fabricated at very high processing temperatures (above 500°C) and their operating voltage is quite high (30-50 V). Here, thin-film transistors (TFT) are reported based upon solution processable indium oxide (In 2 O 3 ) and room temperature processed anodized high- \kappa aluminum oxide (Al 2 O 3 ) for gate dielectrics. The In 2 O 3 TFTs operate well below the drain bias ( \text{V}_{\textsf {ds}} ) of 3.0 V, with on/off ratio 10^{{5}} , subthreshold swing (SS) 160 mV/dec, hysteresis 0.19 V, and low threshold voltage ( \text{V}_{\textsf {th}})~0.6 V. The electron mobility ( { \mu } ) is as high as 3.53 cm ^{{2}} /V.s in the saturation regime and normalized transconductance ( \text{g}_{\textsf {m}} ) is 75~\mu \text{S} /mm. In addition, the detailed capacitance-voltage (C-V) analysis to determine interface trap states density was also investigated. The interface trap density ( \text{D}_{\textsf {it}} ) in the oxide/semiconductor interface was quite low, i.e., {0.99}\times {10}^{{11}} - {2.98}\times {10}^{{11}} eV ^{-{1}}\cdot cm ^{-{2}} , signifying acceptable compatibility of In 2 O 3 with anodic Al 2 O 3 .