1.5-V Operating fully-depleted amorphous oxide thin film transistors achieved by 63-mV/dec subthreshold slope

Thin film transistors (TFTs) with a small subthreshold slope (SS) are urgently required for low-voltage operating circuits on large-area and flexible substrates. Using InGaZnO deposited at room temperature (RT), we achieved 63 mV/dec, the smallest-ever SS reported for oxide semiconductor TFTs. To achieve the small SS as well as small I_off, a fully-depleted off-state was employed by thinning the channel layer to 6 nm. Scalability down to L = 2 mum was confirmed. For V_g = 0 to 1.5 V operation, I_off <10-17 A/mum and on/off ratio > 10⁸ were obtained.