Investigation to the Carrier Transport Properties in Heterojunction-Channel Amorphous Oxides Thin-Film Transistors Using Dual-Gate Bias
Huan Yang, Xiaoliang Zhou, Lei Lü, Shengdong Zhang
Abstract
The carrier transport properties in amorphous oxide semiconductor (AOS) heterojunction thin-film transistors (TFTs) are investigated by using dual gates to control the channel of bilayer AOSs. The mobility of such heterojunction channel exhibited distinct dependences on top-gate (TG) voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\text {TG}}$ </tex-math></inline-formula> ) and bottom-gate (BG) voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\text {BG}}$ </tex-math></inline-formula> ) The mobility was well maintained in TG mode, where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\text {TG}}$ </tex-math></inline-formula> was in line with the build-in electric field of the electron potential well (PW) formed at the heterojunction interface. In contrast, an increased <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\text {BG}}$ </tex-math></inline-formula> gradually reduced the high mobility to the level of a single layer channel, since a high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\text {BG}}$ </tex-math></inline-formula> in the opposite direction of PW could eliminate the PW. This experimentally clarifies that the high-mobility transport path of AOS heterojunction channel locates in the interface PW and its operation demands a proper gate field direction. This were directly consolidated by the disclosed unique capacitance-voltage characteristics.