Low-voltage indium gallium zinc oxide thin film transistors on paper substrates

We have fabricated bottom-gate amorphous (α-) indium-gallium-zinc- oxide (InGaZnO₄) thin film transistors (TFTs) on both paper and glass substrates at low processing temperature (100 °C). As a water and solvent barrier layer, cyclotene (BCB 3022-35 from Dow Chemical) was spin-coated on the entire paper substrate. TFTs on the paper substrates exhibited saturation mobility (μ_sat) of 1.2 cm² V^-1 s ^-1, threshold voltage (V_TH) of 1.9 V, subthreshold gate-voltage swing (S) of 0.65 V decade^-1, and drain current on-to-off ratio (I_ON / I_OFF) of ∼ 10⁴. These values were only slightly inferior to those obtained from devices on glass substrates (μ_sat ∼2.1 cm² V^-1 s ^-1, VTH ∼0 V, S∼0.74 V decade^-1, and I _ON / I_OFF = 10⁵ - 10⁶). The uneven surface of the paper sheet led to relatively poor contact resistance between source-drain electrodes and channel layer. The ability to achieve InGaZnO TFTs on cyclotene-coated paper substrates demonstrates the enormous potential for applications such as low-cost and large area electronics.