Stability characteristics of gallium-doped zinc-tin-oxide thin-film transistors fabricated using a sol-gel method

We investigated the incorporation of Ga into zinc-tin-oxide (ZTO) thin-film transistors (TFTs) and assessed the TFTs' electrical and stability properties. The Ga-doped ZTO (ZTO:Ga) thin films were deposited on thermally oxidized silicon substrates by using a sol-gel technique. The Ga contents were varied from 1 to 20 atomic percent (at.%) while the Zn:Sn ratio was maintained at 1:1. The dependence of the ZTO:Ga thin films' structural properties on the Ga content was analyzed using Xray diffraction (XRD) spectra, scanning probe microscopy (SPM), X-ray photoelectron spectroscopy (XPS), and UV-visible spectrophotometry. The field effect mobilities and the I (on) /I (off) ratios of the ZTO:Ga-TFTs were between 0.68 and 2.95 cm(2)Vs(-1)s(-1) and similar to 10(4) and similar to 10(6), respectively. At low Ga contents, the (< 10-at.%) TFTs displayed similar TFT parameters, but the 20-at.%-Ga TFT showed improved mobility and stability characteristics. Moreover, the 20-at.%-Ga thin film had a smoother surface and increased crystallinity than the low Ga-content samples did.