Source/Drain Series-Resistance Effects in Amorphous Gallium–Indium Zinc-Oxide Thin Film Transistors

In this letter, we investigated the effects of source/drain series resistance on amorphous gallium–indium-doped zinc-oxide (a-GIZO) thin film transistors (TFTs). A linear least square fit of a plot of the reciprocal of channel resistance versus gate voltage yields a threshold voltage of 3.5 V and a field-effect mobility of about 13.5 $\hbox{cm}^{2}/\hbox{V} \cdot \hbox{s}$. Furthermore, in a-GIZO TFTs, most of the current flows in the distance range of 0–0.5 $\mu\hbox{m}$ from the channel edge and shorter than that in a-Si:H TFTs. Moreover, unlike a-Si:H TFTs, a-GIZO TFTs did not show an intersection point, because they did not contain a highly doped ohmic $(\hbox{n}+)$ layer below the source/drain electrodes.