400-V Amorphous IGZO Thin-Film Transistors With Drift Region Doped by Hydrogen
Guangan Yang, Hao Tian, Zuoxu Yu, Tingrui Huang, Yong Xu, Huabin Sun, Weifeng Sun, Wangran Wu
Abstract
The 400-V amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) with the drift region doped by hydrogen near the drain side are demonstrated in this work. The breakdown voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {BD}}$ </tex-math></inline-formula> ) increases with the length of the drift region ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{\text {drift}}$ </tex-math></inline-formula> ), and the maximum <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {BD}}$ </tex-math></inline-formula> of 406 V is achieved at the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{\text {drift}}$ </tex-math></inline-formula> of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5~\mu \text{m}$ </tex-math></inline-formula> for the a-IGZO TFT. The drift region endures the high-operating voltage to enhance the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {BD}}$ </tex-math></inline-formula> , determined by the emission microscope (EMMI) detection and simulation. The output current of the high-voltage (HV) device with the drift region increases with the increasing doping-hydrogen flow rate. The X-ray photoelectron spectroscopy (XPS) proves that the doped-hydrogen improves the carrier concentration in the a-IGZO film. Therefore, the hydrogen doping region takes a low proportion of the whole ON-resistance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ \mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> ). The proposed 400-V a-IGZO TFTs exhibit the excellent <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ \mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> versus <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {BD}}$ </tex-math></inline-formula> tradeoff relationship. The HV device with a drift region doped by hydrogen exhibits a negative shift of the threshold voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> ) under the high bias stress (at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{d} =100$ </tex-math></inline-formula> V and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{g} =5$ </tex-math></inline-formula> V) because of the channel hot-carrier effect.