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

We have fabricated bottom-gate amorphous (alpha-) indium-gallium-zinc-oxide (InGaZnO4) thin film transistors (TFTs) on both paper and glass substrates at low processing temperature (< 100 degrees 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 (mu(sat)) of 1.2 cm(2) 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 similar to 10(4). These values were only slightly inferior to those obtained from devices on glass substrates (mu(sat)similar to 2.1 cm(2) V-1 s(-1), V-TH similar to 0 V, S similar to 0.74 V decade(-1), and I-ON/I-OFF=10(5)-10(6)). 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.