Atomically Thin Molybdenum Disulfide Nanopores with High ...
Atomically Thin Molybdenum Disulfide Nanopores with High Sensitivity for DNA Translocation Ke Liu1, Jiandong Feng1, Andras Kis2 and Aleksandra Radenovic1* 1
Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, 1015 Lausanne, Switzerland 2 Laboratory of Nanoscale Electronics and Structure, Institute of Electrical Engineering, School of Engineering, EPFL, 1015 Lausanne, Switzerland
Table of contents: 1. 2. 3. 4.
Process flow Additional TEM observations pNEB translocation dependence on the pore size Pore conductance as a function of time
1. Process flow
01
KOH etching E‐beam lithography and RIE
02
PMMA as photoresist Opening dimension from 200nm to 500nm
Monolayer MoS2 fabrication
03
Mechanically exfoliated from bulk MoS2 crystals on SiO2 or chemical v apor deposition (CVD) growth meth od on sapphire substrate
MoS2 transfer from SiO2 or sapphir e 04
PMMA as transferring polymer
05
TEM drilling Pore JEOL 2200FS TEM
Substrate is composed of 60 nm of SiO2 and 20 nm of low stress SiNx grown on the both sides by Plas ma‐enhanced chemical vapor deposition (PECVD). Fabrication steps involved here are wet etching, e lectron beam lithography, dry etching and lift‐off.
2. Additional TEM observations
Fig. S1. (a) Low magnification TEM image showing the square‐shaped opening made by RIE. (b) Low magnification TEM image showing the misalignment of the MoS2 onto the square‐shaped opening (example of unsuccessful transfer).
Fig. S2. (a) High‐resolution TEM image revealing atomic structure of MoS2. A diffraction pattern (inset) displays a hexagonal symmetry. (b) Folded edges of a multilayers MoS2. The distance between two layers is 7 Å. This flake is three layers thick.
3. pNEB translocation dependence on the pore size
Fig. S3. (a) Concatenated events of pNEB translocation in 5 nm and 20 nm MoS2 nanopores. Recorded at 400 mV in 2 M KCl. (b) Scatter plot of events.
4. MoS2 nanopore conductance as a function of time
Fig. S4. Pore conductance as a function of the time. Conductance is derived from the baseline current and the applied bias 400 mV. For this device, conductance is around 295 nS ± 32 nS during the whole working period. Translocations can be detected for the whole period with ununiformed capture rate. Two example traces are shown for the 1st hr and for the 9th hr.
Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, 1015 Lausanne, Switzerland 2 Laboratory of Nanoscale Electronics and Structure, Institute of Electrical Engineering, School of Engineering, EPFL, 1015 Lausanne, Switzerland
Table of contents: 1. 2. 3. 4.
Process flow Additional TEM observations pNEB translocation dependence on the pore size Pore conductance as a function of time
1. Process flow
01
KOH etching E‐beam lithography and RIE
02
PMMA as photoresist Opening dimension from 200nm to 500nm
Monolayer MoS2 fabrication
03
Mechanically exfoliated from bulk MoS2 crystals on SiO2 or chemical v apor deposition (CVD) growth meth od on sapphire substrate
MoS2 transfer from SiO2 or sapphir e 04
PMMA as transferring polymer
05
TEM drilling Pore JEOL 2200FS TEM
Substrate is composed of 60 nm of SiO2 and 20 nm of low stress SiNx grown on the both sides by Plas ma‐enhanced chemical vapor deposition (PECVD). Fabrication steps involved here are wet etching, e lectron beam lithography, dry etching and lift‐off.
2. Additional TEM observations
Fig. S1. (a) Low magnification TEM image showing the square‐shaped opening made by RIE. (b) Low magnification TEM image showing the misalignment of the MoS2 onto the square‐shaped opening (example of unsuccessful transfer).
Fig. S2. (a) High‐resolution TEM image revealing atomic structure of MoS2. A diffraction pattern (inset) displays a hexagonal symmetry. (b) Folded edges of a multilayers MoS2. The distance between two layers is 7 Å. This flake is three layers thick.
3. pNEB translocation dependence on the pore size
Fig. S3. (a) Concatenated events of pNEB translocation in 5 nm and 20 nm MoS2 nanopores. Recorded at 400 mV in 2 M KCl. (b) Scatter plot of events.
4. MoS2 nanopore conductance as a function of time
Fig. S4. Pore conductance as a function of the time. Conductance is derived from the baseline current and the applied bias 400 mV. For this device, conductance is around 295 nS ± 32 nS during the whole working period. Translocations can be detected for the whole period with ununiformed capture rate. Two example traces are shown for the 1st hr and for the 9th hr.
