effect of magnetron sputtering parameters and stress state of w film precursors on wse 2 layer texture by rapid selenization

by:ZHENHUA     2020-03-17
Two selenium tungsten (WSe2)
The film was prepared by rapid selenium reaction (W)film.
In order to prevent the WSe2 film from falling off the substrate during the selenium process, the W film has designed a doubleLayer structure.
The first layer is deposited under high sputtering-
The gas pressure forms a loose structure and can be used as a buffer layer to release the stress caused by WSe2 growth.
The second layer is naturally deposited on the first layer in order to react with selenium steam in the next step.
Influence of W film deposition parameters (
Such as time of sputtering, sputtering-
Pressure and substrate bias voltage)
The texture and surface morphology of WSe2 film were studied.
Shorten the sputtering time and increase the sputtering-
Gas pressure or lowering the substrate bias voltage can help to synthesize WSe2 films with more platelets vertically embedded in the substrate.
The stress state of the W film affects the texture of the WSe2 film.
Based on the stress state of W film, a WSe2 film growth model with different textures is proposed.
The insertion direction of van der Waals gap is a key factor in the formation of the heterogeneity of WSe2 film.
Deposition of W film on quartz glass substrate (
25mm x 25mm x 1mm)
Low surface roughness (0. 3u2009nm)by direct-current (DC)
In Ar (99. 999%).
Clean the substrate using standard procedures, including 15 minutes per ultrasound wash in acetone and ethanol.
Save the substrate in ethanol and dry it with nitrogen until it is loaded into the sputtering system.
The deposit chamber is pumped down to background pressure 4. 1u2009×u200910u2009Pa.
The target purity of W is 99. 999%.
In order to achieve the uniformity of the transverse film, the substrate is installed on the rotating bracket.
Distance between targets (Φu2009=u200960u2009mm)
The substrate is 153mm.
Tungsten target is pre-
When the substrate is isolated from the plasma using the shutter, the sputtering is 5 min.
After deposition, use a glass cutter to cut the W film in half.
Half is used for detection and the other half is converted to WSe by exposing the W membrane to Se.
All W sheets are hot.
Treatment under the same selenium condition. High-
Purity Se powder (0. 7u2009g)
Put in the Diamond crucible (3u2009ml).
The experimental setup of the selenium process is shown.
Place the pioneer W film and the Diamond crucible in a sliding furnace.
Both sides of the Kumgang Crucible are sealed with quartz plugs.
The stove is pumped to the background pressure of 1.
0pa Pre-charge protection steam (N 99. 999%).
In order to remove the residual oxygen in the vacuum system, this process is repeated three times.
Finally, N is added to the furnace until the steam pressure reaches 0. 04u2009MPa.
After the furnace temperature reaches 600 °c, push to the other side of the flat slide and meet the sample.
The sample is kept at this temperature for 30 minutes.
Cool the furnace to 500 °c at 10 °c/min.
Finally, the furnace is turned off and the sample is naturally cooled. X-
Ray diffraction (XRD)
Used to characterize orientation and phase microstructure (Rigaku Ltd.
Japanese D/max 2550VB CuK radiation U u2009 40 u2009 kV = I u2009 250 u2009 mA). Field-
Emission scanning electron microscope (
NOVA nano SEM 230)
Used to study the morphology of W and WSe films.
Resolution transmission electron microscopy (
High-resolution transmission electron microscope, Japanese electron Zhuzhou 2010II)
The study was done by immersing the film in diluted HF (~1%).
Due to the weak adhesion to the substrate, the film is easily stripped from the substrate and transferred to the standard (
Amorphous carbon-covered)
Copper mesh for HRTEM analysis.
The residual stress of the film was measured by X-ray diffraction sin laser method (
Brooke D8 found).
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