Mobility Enhancement in P-Type SnO Thin-Film Transistors via Ni Incorporation by Co-Sputtering

Abstract

Oxide semiconductors have been considered one of the most promising candidates for flexible electronics applications owing to their low process temperatures and good reliability. However, the low mobility of p-type oxide semiconductors limits the performance of flexible oxide-TFT-based CMOS technology. In this study, p-type SnO_<i>x</i>:Ni thin films were deposited by reactive rf magnetron co-sputtering, a technique compatible with the current industrial semiconductor manufacturing technology, from Sn and Ni targets. As the Ni-gun power increased, the distribution of Ni in the SnO_<i>x</i>:Ni thin film changed from a more uniform dispersion to nanoclusters, resulting in the crystalline phase transition of SnO_<i>x</i>:Ni from <inline-formula> <tex-math notation="LaTeX">$\alpha $ </tex-math></inline-formula>-SnO (110)-dominant polycrystalline to amorphous and then to <inline-formula> <tex-math notation="LaTeX">$\alpha $ </tex-math></inline-formula>-SnO (101)-dominant polycrystalline. A high-mobility inverted-staggered p-type SnO_<i>x</i>:Ni TFT was then fabricated on a glass substrate with a maximum process temperature of 225&#x00B0;C, which is compatible with flexible polymeric substrates. The TFT fabricated at an optimal Ni-gun power of 42 W exhibited an impressive field-effect mobility of 11 cm²V^&#x2212;1s^&#x2212;1 and on current of <inline-formula> <tex-math notation="LaTeX">$35.2 ~\mu \text{A}$ </tex-math></inline-formula> per channel width-to-length ratio; these values are comparable to those of a typical n-type oxide TFT. These results should contribute toward flexible oxide-TFT-based CMOS technology.