Supporting information

Ultraviolet/ozone and oxygen plasma treatments for improving the contact of carbon

nanotube thin film transistors

Qi Huang1, Jiye Xia1, Jie Zhao1, Guodong Dong1, Fang Liu1, Hu Meng2, Xuelei Liang1,*

1Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics,

Peking University, Beijing 100871, China2BOE Technology Group Co., Ltd., Beijing 100176, China

1. Experimental details for UVO and oxygen plasma treatments

UVO treatment was performed in a commercial UVO cleaner (Jelight Model 42-220). The

average intensity of the grid lamp is 28-32 mW/cm2 @ 253.7 nm. The distance of sample to grid

lamp was kept at 2.2 cm during the treatment.

PR residue removing was also performed by using oxygen plasma treatment in an ICP etcher

(Trion Minilock III). The etching power was set to 100 W and the O2 flow rate was set to 50 sccm.

The chamber pressure was set to two different values, i.e., 200 mT (red curve in Fig. 4) and 150 mT

(blue line in Fig. 4).

2. Height change of the CNTs during the UVO treatment

Since the same area of the CNT film was monitored during the UVO treatment, so we can

compare the height change of the same location of one particular CNT.

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Fig. S1 (a) AFM image of as-deposited CNT film, which was also shown in Fig. 2a of the main

text. The arrow points to the location of a particular CNT which height change was compared

during the UVO treatments. (b) Line profile corresponding to (a). (c) Height change obtained during

the UVO treatment process.

3. UVO treatment of the contact area of a real CNT-TFT device

During the CNT-TFTs fabrication, alignment marks were first fabricated on the substrate, which

allow us to monitor the contact area of the CNT film during the fabrication process according to our

device design.

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Fig. S2 AFM images of the contact area of a CNT-TFT. (a) As-deposited, (b) after photo

lithography, (c) after 6 min of UVO treatment. Due to the high density of the CNT film, the

morphology change is not as clear as those in Fig. 2 of the main text. However, it is still can be seen

clearly that the PR residue was introduced during the fabrication process and cleaned by UVO

treatment.

4. Electrical measurement results of CNT-TFTs experienced various UVO treatments

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Fig. S4 Electrical measurement results of CNT-TFTs experienced various UVO treatments. (a-f)

Output curves, one typical device was shown for each treatment condition. (g-l) transfer curves, 8

devices of each treatment condition were shown.

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