Praseodymium-Doped In-Sn-Zn-O TFTs With Effective Improvement of Negative-Bias Illumination Stress Stability
Hengbo Zhang, Lingyan Liang, Xiaolong Wang, Zhendong Wu, Hongtao Cao
Abstract
In this work, amorphous praseodymium-doped In-Sn-Zn-O (ITZO-Pr) thin-film transistors (TFTs) were fabricated with improved negative-bias illumination stress (NBIS) stability under different radio frequency (RF) magnetron sputtering powers. The optimized ITZO-Pr TFTs presented field effect mobility ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\mu }_{\text{FE}}$ </tex-math></inline-formula> ) of 20.9 cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}\cdot {}\text{V}^{-1}\cdot {}\text{s}$ </tex-math></inline-formula> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> , steep subthreshold (SS) of 0.27 V/dec, and small threshold voltage shift ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\Delta } {V}_{\text{th}} = -2.12$ </tex-math></inline-formula> V) under NBIS (−20 V, 3600 s). All Pr-doped devices exhibited a reduction in light responsivity of more than one order of magnitude compared with ITZO TFTs. Moreover, after Pr doping, relaxation processes of photoelectrons changed and then the activation energy ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\text{a}}$ </tex-math></inline-formula> ) of light-induced electrons relaxation decreased, which enhanced the NBIS stability of ITZO TFTs effectively.