Epitaxial Growth Of Highly Crystalline Monolayer Molybdenum Disulfide Film On Hexagonal Boron NitrideTechnology #16148n
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High Quality Wafer-scale Single Crystalline Monolayer
Molybdenum Disulfide Film
National University of Singapore Industry Liaison Office Technology Offer
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.
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:
large area (>2 inches diameter) continuous single crystalline monolayer MoS2
film are demonstrated.
film has no grain boundaries and low defect density.
fabricated on epitaxial dielectric substrates eg. Hexagonal Boron Nitride or
h-BN, hence device fabrication can be done directly.
procedure utilizes conventional equipment used in the industry.
Molybdenum Disulfide, semiconductor, crystalline, monolayer, epitaxial substrate
ILO Reference: 16148N
IP Status: Patent pending
Prof. Loh Kian Ping email@example.com
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