Large mobility modulation in ultrathin amorphous titanium oxide transistors


Recently, ultrathin metal-oxide thin film transistors (TFTs) have shown very high on-off ratio and ultra sharp subthreshold swing, making them promising candidates for applications beyond conventional large-area electronics. While the on-off operation in typical TFTs results primarily from the modulation of charge carrier density by gate voltage, the high on-off ratio in ultrathin oxide TFTs can be associated with a large carrier mobility modulation, whose origin remains unknown. We investigate 3.5 nm-thick titanium oxide based ultrathin TFTs exhibiting 6-decade on-off ratio, predominantly driven by gate induced mobility modulation. The power law behavior of the mobility features two regimes, with a very high exponent at low gate voltages, unprecedented for oxide TFTs. We find that this phenomenon is well explained by the presence of high-density tail states near the conduction band edge, which supports carrier transport via variable range hopping. The observed two-exponent regimes reflect the bi-exponential distribution of the density of band-tail states. This improved understanding would be significant in fabricating high-performance ultrathin oxide devices.

Metadata Access
Creator Tiwale, Nikhil; Subramanian, Ashwanth; Dai, Zhongwei; Sikder, Sayantani; Sadowski, Jerzy T.; Nam, Chang-Yong
Publisher Materials Cloud
Publication Year 2020
Rights info:eu-repo/semantics/openAccess; Creative Commons Attribution 4.0 International
OpenAccess true
Contact archive(at)
Language English
Resource Type Dataset
Discipline Materials Science and Engineering