Effects of channel stoichiometry and processing temperature on the electrical characteristics of zinc tin oxide thin-film transistors

Thin-film transistor (TFT) structures with zinc tin oxide channel layer are fabricated and electrically characterized; zinc tin oxide composition (Zn:Sn ratio) and post-deposition anneal temperature are varied so as to explore their effects on electrical performance. Channel mobility and turn-on voltage are extracted from measured electrical characteristics, thus mapping TFT performance (for the process and structure used here) across the zinc tin oxide composition/processing temperature space. In general, mobility reaches a broad peak for intermediate compositions and anneal temperatures, while turn-on voltage decreases (becomes increasingly negative) with increasing anneal temperature and decreasing Zn:Sn ratio. These results comprise key information in assessing the potential of zinc tin oxide as a candidate TFT channel layer material.