title: Tuning the threshold voltage of carbon nanotube transistors by n-type molecular doping for robust and flexible complementary circuits.
abstract: Tuning the threshold voltage of a transistor is crucial for realizing robust digital circuits. For silicon transistors, the threshold voltage can be accurately controlled by doping. However, it remains challenging to tune the threshold voltage of single-wall nanotube (SWNT) thin-film transistors. Here, we report a facile method to controllably n-dope SWNTs using 1H-benzoimidazole derivatives processed via either solution coating or vacuum deposition. The threshold voltages of our polythiophene-sorted SWNT thin-film transistors can be tuned accurately and continuously over a wide range. Photoelectron spectroscopy measurements confirmed that the SWNT Fermi level shifted to the conduction band edge with increasing doping concentration. Using this doping approach, we proceeded to fabricate SWNT complementary inverters by inkjet printing of the dopants. We observed an unprecedented noise margin of 28 V at V(DD) = 80 V (70% of 1/2V(DD)) and a gain of 85. Additionally, robust SWNT complementary metal-oxide-semiconductor inverter (noise margin 72% of 1/2VDD) and logic gates with rail-to-rail output voltage swing and subnanowatt power consumption were fabricated onto a highly flexible substrate.
authors.affiliation: Departments of Materials Science and Engineering, Chemical Engineering, Electrical Engineering, and Chemistry, Stanford University, Stanford, CA 94305.
authors.forename: Huiliang
authors.initials: H
authors.lastname: Wang
authors.forename: Peng
authors.initials: P
authors.lastname: Wei
authors.forename: Yaoxuan
authors.initials: Y
authors.lastname: Li
authors.forename: Jeff
authors.initials: J
authors.lastname: Han
authors.forename: Hye Ryoung
authors.initials: HR
authors.lastname: Lee
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Naab
authors.forename: Nan
authors.initials: N
authors.lastname: Liu
authors.forename: Chenggong
authors.initials: C
authors.lastname: Wang
authors.forename: Eric
authors.initials: E
authors.lastname: Adijanto
authors.forename: Benjamin C-K
authors.initials: BC
authors.lastname: Tee
authors.forename: Satoshi
authors.initials: S
authors.lastname: Morishita
authors.forename: Qiaochu
authors.initials: Q
authors.lastname: Li
authors.forename: Yongli
authors.initials: Y
authors.lastname: Gao
authors.forename: Yi
authors.initials: Y
authors.lastname: Cui
authors.forename: Zhenan
authors.initials: Z
authors.lastname: Bao
keywords: CMOS circuit; inkjet-printed; n-doping; nanomaterials