Investigation on the variation of channel resistance and contact resistance of SiZnSnO semiconductor depending on Si contents using transmission line method

•Si atoms in a-SZTO TFTs can act as good carrier suppressor on the electrical property by high binding energy with oxygen.•The sheet and contact resistances of SZTO TFTs were calculated by transmission line method.•The sheet and contact resistances are increase depending on the increase of Si ratio.•The increase of contact resistance could be explained by change of difference between ECM and EF.

Amorphous silicon-zinc-tin-oxide (a-SZTO) thin film transistors (TFTs) have been fabricated depending on the silicon ratio in channel layers. The a-SZTO TFT exhibited high electrical properties, such as high mobility of 23 cm2 V−1 s−1, subthreshold swing of 0.74 V/decade and ION/OFF of 2.8 × 108, despite of the addition of Si suppressor. The physical mechanism on the change of the sheet resistance and the contact resistance in a-SZTO TFT has been investigated and proposed closely related with the Si ratio. Both resistances were increased as increasing Si ratio, which clearly indicated that the role of Si is a carrier suppressor directly leading to the increase of channel and contact resistances. To explain the role of Si as a carrier suppressor, the conduction band offset mechanism has been also proposed depending on the change of carrier concentration in channel layer and at the interface between electrode and channel layer.