Low temperature carrier transport mechanism in high-mobility zinc oxynitride thin-film transistors

Abstract

The authors investigate the low-temperature carrier transport mechanism in high-mobility zinc oxynitride (ZnON) thin-film transistors (TFTs) over a wide range of operating temperatures below room temperature (90–293 K) by analyzing the temperature-dependent field-effect characteristics. In the subthreshold and transition regions, the variable range hopping and trap-limited band transport are considered as dominant carrier transport mechanisms in the ZnON TFT at temperatures below ∼207 K and above ∼243 K, respectively. In the above-threshold region, the field-effect mobility almost linearly depends on 1/T (T: absolute temperature) at all temperatures, which represents that the trap-limited band transport is the dominant carrier transport mechanism through the entire temperature range of 90 to 293 K in the fabricated ZnON TFT. Approximately 1 order of magnitude higher subgap density of states is extracted from the fabricated ZnON TFT compared with a conventional amorphous indium-gallium-zinc oxide TFT, which is primarily attributed to the large number of defective ZnXNY bonds inside the ZnON.