Formation of F-Doped Offset Region for Spray Pyrolyzed Self-Aligned Coplanar Amorphous Zinc–Tin–Oxide Thin-Film Transistor by NF₃ Plasma Treatment

We report the high performance of self-aligned (SA), amorphous zinc-tin-oxide (a-ZTO) coplanar thin-film transistor (TFT) by spray pyrolysis. The a-ZTO thin film deposited by spray at 350 °C has a low surface roughness (0.39 nm) and no bubble. The resistivity of a-ZTO could be decreased to 2 x 10-3 Ωcm by NF3 plasma exposure and it was used for the offset regions of SA coplanar TFT. The coplanar a-ZTO TFT exhibits the field-effect mobility (μFE) of 5.13 cm2V-1s-1, turn-on voltage (VON) of 0 V, the subthreshold swing of 139 mV/decade, and high On/Off-current ratio over 107. The SA coplanar a-ZTO TFT exhibited high stability with a threshold voltage shift (ΔVTH) of 0 V under the gate bias stress of VGS = +20 V for 1 h.