Enhanced Negative Bias Illumination Stability of ZnO Thin Film Transistors by Using a Two-Step Oxidation Method

In this study, we illustrate a novel way to improve the stability under negative bias illumination stress (NBIS) of ZnO thin-film transistors (TFTs) by adding O
₃
treatment after each cycle of growth at 100°C by atomic layer deposition. Compared with the TFTs without O
₃
treatment, the shift of threshold voltage (
$\Delta {V}_{th}$
) is reduced from −4.39 to −0.98 V under NBIS, while the mobility decreased from 31.2 to 18.4 cm
²
V
⁻¹
s
⁻¹
. (H
₂
O and O
₃
as oxidants)/ZnO (H
₂
O as oxidant) bilayer structure, a high filed-effectmobility of 32.1 cm
²
V
⁻¹
s
⁻¹
and an excellent stability (
$\Delta V_{\mathrm {th}} = -2.34$
V) have been obtained simultaneously. These improved performance and stabilities are attributed to the bilayer channel structures and the reduction of
$V_o$
in the ZnO channel layer treated by O
₃
.