Investigation of the contact resistance between amorphous silicon-zinc-tin-oxide thin film transistors and different electrodes using the transmission line method

Abstract

A thin film transistor (TFT) has been fabricated using the amorphous 0.5 wt% Si doped zinc-tin-oxide (a-0.5 SZTO) with different electrodes made of either aluminium (Al) or titanium/aluminium(Ti/Al). Contact resistance and total channel resistance of a-0.5SZTO TFTs have been investigated and compared using the transmission line method (TLM). We measured the total resistance of 1.0×102 Ω/cm using Ti/Al electrodes. This result is due to Ti, which is a material known for its adhesion layer. We found that the Ti/Al electrode showed better contact characteristics between the channel and electrodes compared with that made of Al only. The former showed a less contact and total resistance. We achieved high performance of the TFTs characteristic, such as Vth of 2.6 V, field effect mobility of 20.1 cm2V-1s-1, S.S of 0.9 Vdecade-1, and on/off current ratio of 9.7×106 A. It was demonstrated that the Ti/Al electrodes improved performance of TFTs due to enhanced contact resistance.