Effects of Channel Layer Thickness on Characteristics of Flexible Nickel-Doped Zinc Oxide Thin-Film Transistors

We have fabricated fully transparent high performance flexible nickel-doped zinc oxide thin-film transistors (NZO TFTs) on flexible plastic substrates using magnetron sputtering. The effects of active layer thickness on the performance of NZO TFTs was investigated.We found that the channel layer thickness has a notable influence on the characteristics of NZO TFTs. The electrical characteristics of NZO TFTs reached the optimization when the active channel layer thickness was 71 nm, with a low off-current lower than 1 pA, a high on/off drain current ratio of 2.1 × 10
⁹
, a high saturation mobility of 27.5 cm
²
· V
^-1
· s
^-1
, a steeper subthreshold swing of 67 mV/decade, and a low threshold voltage of 1.88 V. It is demonstrated that NZO is a promising active channel layer materials for future transparent flexible displays.