Fully transparent flexible dual-layer channel Ga-doped ZnO thin-film transistors on plastic substrates

Fully transparent dual-layer Ga-doped zinc oxide (GZO) thin-film transistors (TFTs) were fabricated on flexible plastic substrate by room temperature processes. The GZO thin films are deposited by radio-frequency sputtering according to the variation of the depositing time in order to optimise the performance of GZO TFTs. The results show that dual-layer GZO TFTs exhibit excellent electrical properties, mechanical flexibility and optical transparency. A saturation mobility μ_s of 350 cm²/V.s, a linear field effect mobility of 281 cm²/V.s, a threshold voltage V_TH of 3.2 V, a steep subthreshold swing of 268 mV/decade, a low off-state current value (I_OFF) of 1.5 × 10^-11 A and a high on/off ratio of about 10⁸ were extracted. The TFTs also have admirable transparency with an average visible transmittance of 87.2%. These results indicate that GZO material is suitable for the next generation flexible displays.