Enhancement of electrical characteristics of a-ZTO TFTs based on channel layers produced with alternating precursor concentration

Abstract

The enhancement in electrical characteristics of the thin film transistors (TFTs) based on the mixed-stacked amorphous zinc tin oxide (a-ZTO) with an alternating precursor concentration is reported. The channel layers were deposited via sol-gel on oxidised p-Si. The source/drain ohmic contacts were prepared on the ZTO layer, constructing the bottom-gate TFTs. In this investigation, the TFTs with the following three channel layers were fabricated, and their characteristics were compared; (i) four layers produced from 0.05 M precursor solution, (ii) four layers produced from 0.2 M precursor solution, and (iii) four layers with alternating 0.05 and 0.2 M precursor solutions. It was found that the mobility (5.3 cm2/V s) of the TFT fabricated with the channel layers with alternating precursor concentration was higher than those with single concentration. Although the mechanism for this mobility enhancement is still being further analysed, it was conjectured that alternating precursor concentration might have reduced the trap density in the transistor channel and/or ZTO/SiO2 interfaces.