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Novel Tunnel-Contact-Controlled IGZO Thin-Film Transistors with High Tolerance to Geometrical Variability

Sporea, Radu A., Niang, Kham M., Flewitt, Andrew J. and Silva, S. Ravi P. Silva (2019) Novel Tunnel-Contact-Controlled IGZO Thin-Film Transistors with High Tolerance to Geometrical Variability Advanced Materials.

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For the first time, thin insulating layers are used to modulate a depletion region at the source of a thin-film transistor. Bottom contact, staggered electrode transistors fabricated using RFsputtered IGZO as the channel layer, with a 3 nm ALD Al2O3 layer between the semiconductor and Ni source-drain contacts show behaviours typical of source-gated transistors (SGTs): low saturation voltage (VD_SAT ~ 3V), change in VD_SAT with gate voltage of only 0.12 V/V and flat saturated output characteristics (small dependence of drain current on drain voltage). The transistors show high tolerance to geometry variations: saturated current changes only 0.15x for channel lengths between 2 - 50 μm, and only 2x for sourcegate overlaps between 9 - 45 μm. A higher than expected (5x) increase in drain current for a 30K change in temperature, similar to Schottky-contact SGTs, underlines a more complex device operation than previously theorised. Optimizations for increasing intrinsic gain and reducing temperature effects are discussed. These devices complete the portfolio of contactcontrolled transistors, comprising devices with: Schottky contacts, bulk barrier or heterojunctions, and now, tunnelling insulating layers. The findings should also apply to nanowire transistors, leading to new low-power, robust design approaches as large-scale fabrication techniques with sub-nanometre control mature.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Electronic Engineering
Authors :
Sporea, Radu
Niang, Kham M.
Flewitt, Andrew J.
Silva, S. Ravi P.
Date : 2019
Funders : Royal Academy of Engineering, Engineering and Physical Sciences Research Council (EPSRC)
Grant Title : Research Fellowship
Copyright Disclaimer : © 2019 John Wiley & Sons Ltd.
Uncontrolled Keywords : Tunnel barriers; Thin-film transistors; Source-gated transistors; IGZO; Amorphous oxide semiconductors
Related URLs :
Depositing User : Clive Harris
Date Deposited : 27 Jun 2019 11:26
Last Modified : 27 Jun 2019 11:26

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