title: Fabrication of air-stable n-type carbon nanotube thin-film transistors on flexible substrates using bilayer dielectrics.
abstract: Single-walled carbon nanotube (SWNT) thin-film transistors hold great potential for flexible electronics. However, fabrication of air-stable n-type devices by methods compatible with standard photolithography on flexible substrates is challenging. Here, we demonstrated that by using a bilayer dielectric structure of MgO and atomic layer deposited (ALD) Al2O3 or HfO2, air-stable n-type devices can be obtained. The mechanism for conduction type conversion was elucidated and attributed to the hole depletion in SWNT, the decrease of the trap state density by MgO assimilating adsorbed water molecules in the vicinity of SWNT, and the energy band bending because of the positive fixed charges in the ALD layer. The key advantage of the method is the relatively low temperature (120 or 90 °C) required here for the ALD process because we need not employ this step to totally remove the absorbates on the SWNTs. This advantage facilitates the integration of both p-type and n-type transistors through a simple lift off process and compact CMOS inverters were demonstrated. We also demonstrated that the doping of SWNTs in the channel plays a more important role than the Schottky barriers at the metal contacts in carbon nanotube thin-film transistors, unlike the situation in individual SWNT-based transistors.
authors.affiliation: State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics & Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China. qunqli@mail.tsinghua.edu.cn and Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Guanhong
authors.initials: G
authors.lastname: Li
authors.affiliation: State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics & Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China. qunqli@mail.tsinghua.edu.cn and Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Qunqing
authors.initials: Q
authors.lastname: Li
authors.affiliation: State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics & Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China. qunqli@mail.tsinghua.edu.cn and Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Yuanhao
authors.initials: Y
authors.lastname: Jin
authors.affiliation: State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics & Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China. qunqli@mail.tsinghua.edu.cn and Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Yudan
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics & Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China. qunqli@mail.tsinghua.edu.cn and Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Xiaoyang
authors.initials: X
authors.lastname: Xiao
authors.affiliation: State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics & Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China. qunqli@mail.tsinghua.edu.cn and Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Kaili
authors.initials: K
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics & Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China. qunqli@mail.tsinghua.edu.cn and Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Jiaping
authors.initials: J
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics & Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China. qunqli@mail.tsinghua.edu.cn and Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Shoushan
authors.initials: S
authors.lastname: Fan