One-Step Synthesis of Lateral WS2/MoS2 Heterostructures via Microfabrication with Differing Layers of Transition Metal Oxides
2017 MRS Fall Meeting & Exhibit
Shichen Fu, Kyungnam Kang, Xiaotian Wang, Kyle Godin, Anthony Palumbo and Eui-Hyeok Yang*
Hynes Convention Center Boston, Massachusetts
Department of Mechanical Engineering, Stevens Institute of Technology, NJ 07030 Contact: Prof. EH Yang,
[email protected]
Background
Growth Parameters
Project Overview
• Lateral TMD heterostructures can be used for p-n diodes, photodiodes and complementary inverters with a high voltage gain.
• The fabrication of TMD lateral heterostructures with clean and sharp interfaces is crucial for electronic and optoelectronic device applications. • Post-lithography and layer transfer processes can induce contamination to the heterostructures. • The one-step contact-growth enables the growth of specific shapes of TMD lateral heterostructures, which is facilitated by selectively pre-patterning two types of transition metal oxides (TMO) films.
• Lateral TMD heterostructures cannot be made using conventional transfer methods. • There are two different CVD methods for creating lateral TMD heterostructures.
• Large area growth of WS2 and MoS2 monolayers Monolayer MoS2
Monolayer WS2
300 μm
300 μm
30 μm
30 μm
• Specific patterns of TMO films
Source Substrate Preparation
• Two-step growth
WS2
WS2
• One-step growth Photolithography
X powder M1 powder Substrate Open-air Carrier Gas X powder
One-Step Growth
Two-Step Growth
Carrier Gas
Lift-off
30 μm
E-beam Physical Vapor Deposition (PVD)
Photolithography
Lift-off
• One-step growth condition
Carrier Gas X powder
E-beam Physical Vapor Deposition (PVD)
One-step, contact-growth
Carrier Gas
M Coated Source Chip
X powder Substrate
M2 powder Substrate
Chalcogenide
Recipe for One‐Step Growth MoS2/WS2 Heterostructure
M Coated Source Chip Sandwich two chips Substrate
Transition Metal Oxide SiO2/Si Substrate
Si/SiO2
• Manipulate the growth recipe and shapes of TMO patterns to obtain the WS2/MoS2 lateral heterostructures
WO3
WO3
Lateral Heterostructures WS2
300 μm
MoS2
30 μm
E12g = 384
A1g = 405
Si/SiO2
MoS2 Raman
Raman Shift (cm-1)
300 μm
MoS2
MoS2 PL
Energy (eV)
1.97
A1g = 417
Intensity (A.U.)
WS2
Intensity (A.U.)
Sample 2
MoO3
128
1.84 Intensity (A.U.)
MoS2
MoS2
108
• Compare performances between p-n diodes made using lithography vs. one-step growth
Raman and PL Spectra
Lift-off
WO3/MoO3 arrays
93
• Characterize electrical and optical properties
30 μm
E12g = 356 WO3
85
• Optimize the pattern geometry for clean laterally stitched TMDs
MoO3
MoO3
Sample 1
15 μm
70
• Optimize the growth recipe Si
• Adjust the TMO patterns to enable the growth of location specific and lateral WS2/MoS2 heterostructures
10
On-Going Work
Differing Layers of TMO
Intensity (A.U.)
• Create alternating patterns of transition metal oxide films on the source substrate
30 μm
0
Results-To-Date
Research Task
Lift-off
Contact the source and growth substrates face-to-face
TMO deposited
900 800 700 600 500 400 300 200 100 0
• The one-step growth technique enables the fabrication of lateral heterostructures. • The process reduces process steps, thus potentially minimizing contamination between layers during the process.
30 μm Raman Shift (cm-1)
Technological Impacts
Energy (eV)
