Low temperature characteristics in amorphous indium-gallium-zinc-oxide thin-film transistors down to 10 K

We report on the characteristics of amorphous indium-gallium-zinc-oxide thin-film transistors (TFTs) in the temperature range of 10–300 K. In the range of 80–300 K, the transfer characteristics are consistent with thermally activated band conduction. Below 80 K, the drain current vs. temperature behavior follows Mott's law, exp(−B/T−1/4), with constant B, indicating variable range hopping. The subthreshold swing of the TFT remains unchanged in the band conduction region, but it increases rapidly with decreasing temperature below 80 K. With decreasing temperature, the hopping activation energy decreases and hopping distance increases, and are 16.8 meV and ∼11.6 nm, respectively, at 60 K.