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Epitaxial Growth Of Highly Crystalline Monolayer Molybdenum Disulfide Film On Hexagonal Boron Nitride

Technology #16148n

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Prof. Loh Kian Ping
chmlohkp@nus.edu.sg
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Dr Tan Yan Ny
Manager (65)66012812
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Tech Offer 16148N Epitaxial Growth Crystalline Disulfide Film [PDF]

High Quality Wafer-scale Single Crystalline Monolayer

Molybdenum Disulfide Film

National University of Singapore    Industry Liaison Office    Technology Offer

Market Need

With the miniaturization of modern electronic and optoelectronic circuits, searching for new class of semiconducting materials with reduced dimension is highly desired. MoS2 is a representative semiconducting transition metal dichalcogenide (TMDC) which is attractive as it can be thinned down to the ultimate 2D limit ie. Three atom thick monolayers. However, challenges remain as current fabrication methods eg. chemical vapor deposition (CVD) yield poor quality films which are polycrystalline with a large number of defects and grain boundaries. Hence, there is an urgent need for a fabrication method that yields large area, single crystalline monolayer MoS2 film of high quality.

Solution

Prof. Loh Kian Ping’s group from the Department of Chemistry has developed a preparation strategy for growing wafer-scale, continuous single crystalline monolayer MoS2 film on epitaxial substrates. As the film is fabricated on epitaxial substrates, device fabrication can be done directly on the as-grown film ie. there is no need for transfer process. The as-grown film shows optical properties that are characteristic of monolayer MoS2. More importantly, due to its high crystallinity, the film shows superior electrical properties that are comparable to the best values reported so far for both exfoliated natural single crystalline MoS2 monolayers. This opens up opportunities for electronic and optoelectronic circuits applications with 2D semiconducting materials.

 

FIG. 1: Growth of monolayer MoS2 film on a 2-inch BN/Sapphire wafer. (a) Photograph of the as-grown wafer-scale MoS2 film. (b) Typical Raman spectrum taken at a random point. The peak spacing between E2g1 and A1g is ~ 21.0 cm-1 , indicating monolayer thickness of the film. (c) Raman mapping of the characteristic E2g1 peak at different regions of the wafer. Scale bar: 20 μm. The uniform peak intensity at different areas further confirmed the wafer-scale homogeneity of the as-grown film

 

FIG. 2: Electrical characterization. (a) Output characteristics of monolayer MoS2 FET at different top-gate bias voltages. The linear curves indicate ohmic contact was achieved. (b) Room-temperature transfer curve of the monolayer MoS2 FET shown in (a) with 0.1 V applied source-drain bias voltage in two-probe measurement configuration. The top gate dielectric is a layer of 50 nm ALD-grown HfO2 film. The 285-nm-thick SiO2 acts as back gate, which is grounded when top gate is swept. Inset: optical image of the Hall bar device. The channel length is 22 μm and width is 4.5 μm.

Application and Advantages

Potential application is as an ultra-thin semiconducting substrate for various electronic devices such as high speed field effect transistors, photodetectors, electronic and optoelectronic devices.

Our Value Proposition:

  • High quality, large area (>2 inches diameter) continuous single crystalline monolayer MoS2 film are demonstrated.
  • Fabricated MoS2 film has no grain boundaries and low defect density.
  • Films are fabricated on epitaxial dielectric substrates eg. Hexagonal Boron Nitride or h-BN, hence device fabrication can be done directly.
  • Fabrication procedure utilizes conventional equipment used in the industry.

Keywords

Molybdenum Disulfide, semiconductor, crystalline, monolayer, epitaxial substrate

ILO Reference: 16148N

IP Status: Patent pending

Principal Inventor

Prof. Loh Kian Ping chmlohkp@nus.edu.sg

Get in touch with the Technology Manager

Tan Yan Ny

Email:  tan.yan.ny@nus.edu.sg

Phone: +65-66012812