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(Color) (a) and (b) Transfer curves for the (a) unpassivated and (b) Y2O3-passivated TFTs before (blue lines) and after (red lines) performing CCS tests. (c) and (d) Hysteresis in transfer characteristics at VDS = 10 V for the (c) unpassivated and (d) Y2O3-passivated TFTs before the CCS tests. The sweep rate was ∼9 V/s. (e) Variations of ΔVth over time under CCS for the unpassivated (black circles), Y2O3-passivated (red circles), and Al2O3-passivated (blue circles) TFTs. The ΔVth of unpassivated TFTs was also measured under vacuum (black open circles).
(Color) Time dependence of transfer curves during NBS and NBLS testing for the (a) and (b) unpassivated and (c) and (d) Y2O3-passivated TFTs. (e) and (f) Variation of transfer curves as a function of photon energy for the (e) unpassivated and (f) Y2O3-passivated TFTs. The photon energy was varied from 1.8 to 3.4 eV (λ = 700 to 365 nm). (g) Variation of TFT parameters (Vth, S, and μ sat) as a function of photon energy.
(Color) (a) Illustration of the band diagram and defect states to explain the instability observed during NBLS testing. (b) Variation of ΔVth as a function of the number of photons absorbed in the channel or depletion layer during NBLS testing for unpassivated TFTs containing wet annealed channels. The inset shows the same data plotted against stress time. (c) ΔVth plotted against the penetration depth (l ph) of the illuminated photons into the a-IGZO channel for TFTs with a 250 nm-thick channel during NBLS testing as a function of stress time. l ph varied from 25 to 260 nm corresponding to photon energies from 6.0 to 3.6 eV, as shown in the inset. (d) The relationship between l ph and the charge density at the interface (ΔD it ) estimated from TFT simulations.
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