2
Taiyu Jin
1*
, Jinyeong Kang
2*
, Eok Su Kim
3
, Sunhee Lee
3
†
, Changgu Lee
1,2,4
†
1 Sungkyunkwan Advanced Institute of Nanotechnology, Sungkyunkwan University,
2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi, Republic of Korea
2 School of Mechanical Engineering, Sungkyunkwan University, 2066, Seobu-ro.,
Jangan-gu, Suwon, Gyeonggi, Republic of Korea
3
Samsung Advanced Institute of Technology, San 14, Nongseo-dong, Giheung-gu,
Yongin, Gyeonggi, Republic of Korea
4
IBS Center for Integrated Nanostructure Physics (CINAP), Institute for Basic
Science (IBS), Sungkyunkwan University, Republic of Korea
* These authors contributed equally to this work.
† peterlee@skku.edu, sunhee77.lee@samsung.com

Although the yield of the supported MoS2 devices was high, MoS2 in many of the devices collapsed to the etched substrate after the suspension process in the critical point dryer (CPD). As a result, the yield of producing completely suspended MoS2 device was about 25%. When a device was not suspended, this failed case could be identified with an optical microscope (Fig. S1). The color seemed much lighter compared to the suspended one (Fig. 2a). Also through an atomic force microscope
(AFM) and a scanning electron microscope (SEM), we could clearly tell if the MoS
2 film was suspended. When the SiO
2
substrate was etched using BOE solution, the
SiO
2
under MoS
2
monolayer was also removed at the same time as in the case of suspended graphene.
S1 The MoS
2
monolayer will never collapse if the MoS
2 monolayer played a role of BOE mask as the metal leads did at the etching process. It seems that BOE permeates between SiO
2
and MoS
2
easily etching the oxide as in other area.
S2
Also according to the transport measurement results, MoS
2
is inert to
BOE at least for a few minutes of exposure.
We have performed a simulation to calculate the real capacitance value of a suspended device using FEMLAB. The vacuum and oxide gaps are 150nm commonly and the width and length of the MoS
2
membrane are 0.77 and 0.91um respectively.

The calculated capacitance value of the device is 4.805 nF/cm 2 , which is about 2% higher than the value from the theoretical model.
Our measurements of transport were repeatable in other devices also. Fig. S3 shows transport results of two additional devices. These curves show almost the same trend with the result in the main text. We compared mobility and on/off ratio in suspended devices with supported devices, both of them were increased 2-10 times.
Device a : mobility increase X2, on/off ratio X3
Device b: mobility increase X10, on/off ratio X10

Fig. S1 Collapsed MoS
2
film. (a) Optical image, (b) AFM image and (c) SEM image
Fig. S2 Simulation model geometry for capacitance of suspended device

Fig. S3 I ds
-V gs
curves of two devices measured from supported and suspended states respectively. (a) device a (b) device b
S1. K. I. Bolotin, K. J. Sikes, Z. Jiang, M. Klima, G. Fudenberg, J. Hone, P. Kim and H. L. Stormer, Solid State Commun , 2008, 146 , 351-355.
S2. E. Stolyarova, D. Stolyarov, K. Bolotin, S. Ryu, L. Liu, K. T. Rim, M. Klima,
M. Hybertsen, I. Pogorelsky, I. Pavlishin, K. Kusche, J. Hone, P. Kim, H. L.
Stormer, V. Yakimenko and G. Flynn, Nano Lett , 2009, 9 , 332-337.