Large mobility modulation in ultrathin amorphous titanium oxide transistors
| Autor: | Ashwanth Subramanian, Jerzy T. Sadowski, Nikhil Tiwale, Zhongwei Dai, Chang-Yong Nam, Sayantani Sikder |
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| Rok vydání: | 2020 |
| Předmět: |
Electron mobility
Materials science business.industry Transistor Oxide 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Variable-range hopping 0104 chemical sciences Titanium oxide law.invention Amorphous solid chemistry.chemical_compound chemistry Mechanics of Materials law Modulation Thin-film transistor Optoelectronics General Materials Science 0210 nano-technology business |
| Zdroj: | Communications Materials. 1 |
| ISSN: | 2662-4443 |
| Popis: | 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 TiOx-based ultrathin TFTs exhibiting on-off ratio of ~106, predominantly driven by ~6-decade 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. The origin of large mobility modulation in ultrathin oxide transistors, promising for their high on-off ratio, remains mostly unknown. Here, a 106 gate-induced mobility modulation in 3.5 nm-thick TiOx transistors is explained by a high density of tail states, mediating variable range hopping of carriers. |
| Databáze: | OpenAIRE |
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