Effects of active layer thickness on the electrical characteristics of solution processed In-Ga-Zn-O TFTs

The solution-processed a-IGZO TFTs with different active layer thickness (t_active) were fabricated with bottom-gate top-contact architectures in this paper. The change of t_active is expected to affect the electrical properties of transistors. The multi-stacked active layer shows both the decreased turn on voltage and threshold voltage owing to the increased free carriers in the channel. The mobility, On/Off ration (I_on/I_off), and subthreshold swing (SS) degraded with the increase of the t_active, resulting from the increased surface roughness and the increased trap density capturing electrons. During stacking layers using solution process, the repeated deposition of layers causes the increased pores in the film, which also leads to the degradation of the mobility, I_on/I_off, and SS.