阅读说明：本技术 悬浮二维材料光致发光的光电调控器及制备、调控方法 (Suspended two-dimensional material photoluminescence photoelectric regulator and preparation and regulation methods ) 是由 李宝军 严佳豪 杨国伟 于 2019-09-04 设计创作，主要内容包括：本发明公开了一种悬浮二维材料光致发光的光电调控器及制备、调控方法,利用化学气相沉积系统在SOI衬底上镀30nm氧化层,并利用聚焦离子束刻蚀技术在SOI衬底上刻蚀覆盖有氧化层的Si纳米条,再利用干法转移将单层或双层WS<Sub>2</Sub>扣在Si纳米条上方,然后在WS<Sub>2</Sub>上定点添加的源漏电极,在Si纳米条刻蚀区域镀金作为栅极,形成光电调控器。本发明制备方法简单快捷,稳定性高,所制备的光电调控器厚度非常薄,具有很高的响应速度,通过光电调制器可以观察到了对单层和双层WS<Sub>2</Sub>光致发光的反常调控,增强WS<Sub>2</Sub>的光致发光的同时,引入静电掺杂和应力机制。(The invention discloses a suspended two-dimensional material photoluminescence photoelectric regulator and a preparation and regulation method thereof, wherein a chemical vapor deposition system is utilized to plate a 30nm oxide layer on an SOI substrate, a focused ion beam etching technology is utilized to etch a Si nano strip covered with the oxide layer on the SOI substrate, and then a dry transfer method is utilized to transfer a single-layer or double-layer WS 2 Buckled over Si nanoribbons and then over WS 2 And (4) adding a source-drain electrode at a fixed point, and plating gold in the Si nano strip etching area to be used as a grid electrode to form the photoelectric regulator. The preparation method is simple and quick, the stability is high, the prepared photoelectric regulator is very thin in thickness and has very high response speed, and the single-layer WS and the double-layer WS can be observed through the photoelectric modulator 2 Anomalous regulation of photoluminescence, enhancement of WS 2 while photoluminescence, electrostatic doping and stress mechanism are introduced.)

1. The preparation method of the suspended two-dimensional material photoluminescence photoelectric regulator is characterized by comprising the following steps of:

Step S1: preparing an SOI substrate, and plating 30nm SiO on the SOI substrate by inductively coupled plasma chemical vapor deposition₂A film;

Step S2: processing the coated SOI substrate by using an FIB etching technology, etching two rectangular areas, wherein the distance between the two rectangular areas is 200-1000nm, the etching depth is 50-200nm, and Si nano-strips are formed between the two rectangular areas;

Step S3: to WS₂Mechanically peeling the single wafer, and removing WS₂transferring to PDMS substrate, and distinguishing single-layer WS and double-layer WS according to different layer contrast under microscope₂An area;

Step S4: under microscope, WS will be attached₂The PDMS substrate is reversely arranged on a mobile platform, transferred to an etched SOI substrate through a mobile platform, slowly pressed down and slowly lifted, and the WS is₂The wafer is attached to the etching area;

Step S5: WS at both ends of Si nanoribbon using maskless lithography₂Etching the upper sealed area, plating a gold film on the sealed area by electron beam evaporation to form a source/drain electrode, and etching the two sides of the Si nano strip by electron beam evaporation to expose the Si layer but not cover the WS₂The area of (a) is gold plated as a gate.

2. The method for manufacturing a suspended two-dimensional photoluminescent photoelectric modulator according to claim 1, wherein in step S1, the thickness of the upper-layer monocrystalline silicon nano-film on the SOI substrate is 200nm, and the thickness of the oxide layer is 375 nm.

3. The method for manufacturing a photoluminescence photoelectric modulator of a suspended two-dimensional material according to claim 1, wherein in step S2, the FIB etching employs an FIB-SEM dual-beam workstation, and the etching beam is 5 nA.

4. The method for manufacturing a suspended two-dimensional photoluminescent optoelectric modulator of claim 1, wherein the two rectangles have a length of 20 μm to 50 μm and a width of 5 μm to 15 μm in step S2.

5. The method for preparing a suspended two-dimensional photoluminescent optoelectric modulator of claim 1, wherein the step of mechanically peeling the WS block in step S3₂Placing the single chip on transparent adhesive tape, repeatedly sticking and peeling to obtain thin laminated sheet, and placing WS on the adhesive tape₂The laminate was transferred over a 1.5cm by 1.5cm PDMS substrate and repeatedly pressed with a cotton swab, and after standing for a while, the tape was slowly peeled off.

6. the method for preparing a suspended two-dimensional photoluminescent photoelectric controller according to claim 1, wherein in step S4, a moving platform is built beside a microscope, and a metal rod is used to attach WS₂The PDMS substrate of the sheet was inverted and placed on the moving platform.

7. The electro-optic modulator prepared by the method for preparing the electro-optic modulator for suspending photoluminescence of two-dimensional material according to any one of claims 1 to 6, wherein the electro-optic modulator comprises a Si nano-strip, and WS is carried above the Si nano-strip₂WS at both ends of Si Nano-strip₂Source and drain electrodes are arranged on the silicon nano-strip, and WS is not covered on two sides of the Si nano-strip₂The region of (2) is provided with a gate.

8. The method of claim 7, wherein the source and drain electrodes of the photo-modulator are applied with a voltage, and then a laser beam with a wavelength of 514nm is appliedFocusing on Si nano-strip, and making WS on Si nano-strip by means of objective lens₂The generated photoluminescence signals are collected, and the photoluminescence signals with different wavelengths are separated in space through a spectrometer and projected to a CCD detector to form a spectrum.

9. The method of claim 8, wherein the voltage is increased or decreased by 1V from 0V to ± 10V.

10. The method of claim 8, wherein the objective lens has a magnification of 50 times and a numerical aperture of 0.75.

Technical Field

The invention belongs to the technical field of suspended two-dimensional material photoluminescence, and relates to a suspended two-dimensional material photoluminescence photoelectric regulator and a preparation and regulation method thereof.

background

Single or double layer transition metal sulfides (TMDC) have unique physical properties and luminescence characteristics. Previously, plasmonic nanostructures and photonic crystal structures were designed to enhance the interaction of light with a substance, thereby enhancing exciton emission from TMDC layered materials. Recently, all-dielectric nanostructures that can generate Mie resonances have brought new mechanisms for applications in the field of nanophotonics. In the application of regulating and controlling the two-dimensional material luminescence, the optimal situation is to realize the amplification and real-time regulation and control of the photoluminescence signal at the same time. The study on two-dimensional material photoluminescence modulation has mainly focused on single-layer TMDC, whereas the phenomenon of electroluminescence modulation is difficult to observe for double-layer TMDC. At present, the regulation and control of two-dimensional material photoluminescence are mainly carried out by applying grid voltage, the change of the grid voltage can cause the electrostatic doping and carrier concentration change of different degrees of single-layer TMDC, so that exciton luminescence is changed, and the electrostatic doping is realized by using a nano grid, so that whether different physical effects exist or not is worthy of further research.

Disclosure of Invention

In order to achieve the purpose, the invention provides a suspended two-dimensional material photoluminescence photoelectric regulator and preparation and regulation methods thereof, the preparation method is simple and rapid, the stability is high, the prepared photoelectric regulator is very thin in thickness and has very high response speed, and the single-layer WS and double-layer WS can be observed through the photoelectric modulator₂Anomalous regulation of photoluminescence, enhancement of WS₂While photoluminescence, electrostatic doping and stress mechanism are introduced.

The invention adopts the technical scheme that the preparation method of the suspended two-dimensional material photoluminescence photoelectric regulator comprises the following steps:

Step S1: preparing an SOI substrate, and plating 30nm SiO on the SOI substrate by inductively coupled plasma chemical vapor deposition₂A film;

Step S2: processing the coated SOI substrate by using an FIB etching technology, etching two rectangular areas, wherein the distance between the two rectangular areas is 200-1000nm, the etching depth is 50-200nm, and Si nano-strips are formed between the two rectangular areas;

Step S3: to WS₂Mechanically peeling the single wafer, and removing WS₂Transferring to PDMS substrate, and distinguishing single-layer WS and double-layer WS according to different layer contrast under microscope₂An area;

step S4: in thatUnder microscope, WS will be adhered to₂The PDMS substrate is reversely arranged on a mobile platform, transferred to an etched SOI substrate through a mobile platform, slowly pressed down and slowly lifted, and the WS is₂the wafer is attached to the etching area;

Step S5: WS at both ends of Si nanoribbon using maskless lithography₂Etching the upper sealed area, plating a gold film on the sealed area by electron beam evaporation to form a source/drain electrode, and etching the two sides of the Si nano strip by electron beam evaporation to expose the Si layer but not cover the WS₂The area of (a) is gold plated as a gate.

Further, in step S1, the thickness of the upper-layer monocrystalline silicon nano-film on the SOI substrate is 200nm, and the thickness of the oxide layer is 375 nm.

Further, in step S2, the FIB etching employs an FIB-SEM dual-beam workstation, and the etching beam current is 5 nA.

Further, the two rectangles in step S2 have a length of 20 μm to 50 μm and a width of 5 μm to 15 μm.

Further, mechanical peeling, WS S3₂Placing the single chip on transparent adhesive tape, repeatedly sticking and peeling to obtain thin laminated sheet, and placing WS on the adhesive tape₂The laminate was transferred over a 1.5cm by 1.5cm PDMS substrate and repeatedly pressed with a cotton swab, and after standing for a while, the tape was slowly peeled off.

Further, in step S4, a moving platform is set up beside the microscope, and a metal rod is used to attach the WS₂The PDMS substrate of the sheet was inverted and placed on the moving platform.

The photoelectric controller prepared by the preparation method of the photoelectric controller of the suspension two-dimensional material photoluminescence comprises a Si nano-strip, and WS is carried above the Si nano-strip₂WS at both ends of Si Nano-strip₂Source and drain electrodes are arranged on the silicon nano-strip, and WS is not covered on two sides of the Si nano-strip₂The region of (2) is provided with a gate.

The method for regulating and controlling by adopting the photoelectric regulator applies voltage to a source electrode and a drain electrode of the photoelectric regulator, then focuses laser with the wavelength of 514nm on the Si nano strip, and then leads WS on the Si nano strip to pass through an objective lens₂The resulting photoluminescent messageThe photoluminescence signals with different wavelengths are collected, separated in space by a spectrograph and projected to a CCD detector to form a spectrum.

Further, the voltage is increased or decreased by 1V from 0V to + -10V.

Further, the magnification of the objective lens is 50 times, and the numerical aperture is 0.75.

Compared with the prior art, the invention has the following beneficial effects:

1. The invention firstly combines the Si nano-strip and the two-dimensional material WS₂In combination, a suspended two-dimensional material photoelectric regulation device controlled by a nano grid is constructed, a new thought is provided for the design of a dynamically regulated silicon-based photoelectric device, and a new method is provided for the combination with a two-dimensional material.

2. The invention adopts FIB etching technology to prepare Si nano-strip, and transfers the two-dimensional material WS by dry method₂The preparation method has the advantages of simple and quick whole preparation process and high stability by transferring the silicon nano-rods on the Si nano-rods, and does not need to use complex electron beam exposure and etching processes.

3. The invention adopts two-dimensional materials to ensure that the thickness of the photoelectric regulation device is very thin, has very high response speed and is beneficial to the nano photoelectric integration in the future.

4. According to the regulation and control method, the resonance generated by the Si nano-strip can enhance the single-layer WS when no voltage is applied₂The enhancement effect is in the double-layer WS₂The middle is more obvious; electrostatic doping and stress effects act simultaneously when a voltage is applied, and the existence of the two mechanisms leads to abnormal regulation of exciton luminescence; single layer WS₂The variation of photoluminescence along with the grid voltage is different from the variation based on the traditional grid regulation, and meanwhile, the grid voltage applied by the Si nano-strip can also be applied to the double-layer WS₂The photoluminescence signal of (a) is enhanced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a photovoltaic device using Si nano-strips as a grid to regulate the luminescence of a two-dimensional material.

Fig. 2a is a bright field optical micrograph of an etched Si nanoslit sample of the invention.

Fig. 2b is a dark field optical micrograph of an etched Si nanoribbon sample of the invention.

fig. 2c is a bright field optical microscope photograph of the Si nanoribbons of the present invention after transfer of the two-dimensional material.

FIG. 2d is a bright field optical microscope photograph after the source/drain electrodes are added at fixed points.

Fig. 2e is a small scale bright field optical microscope photograph of the complete device of the invention and a schematic view of the electrode arrangement.

Fig. 2f is an atomic force microscope image of the Si nanoribbons of the present invention and height data.

FIG. 2g is a Si-WS according to the present invention₂SEM image of the photo-modulator.

Fig. 3 is a schematic illustration of the interaction of a two-dimensional material as a dipole light source with Si nanostructures.

Fig. 4a is a schematic view of the tested area of the present invention, the numbers indicating the landing points of the laser spots.

FIG. 4b shows a single layer WS according to the present invention₂The intensity of photoluminescence varied in three cases.

FIG. 4c shows a double-layered WS according to the present invention₂The intensity of photoluminescence varied in three cases.

FIG. 5 is a schematic diagram of an electrically controlled photoluminescence mechanism of the invention.

FIG. 6a shows a Si nanostrip-monolayer WS of the present invention₂In the photo-modulator, photoluminescence is dynamically changed with positive and negative voltages.

FIG. 6b shows Si nanostrip-bilayer WS of the present invention₂in the photo-electric modulator, photoluminescence is dynamically changed with one of positive and negative voltages.

FIG. 6c shows Si nanoribbon-bilayer WS of the present invention₂In the photoelectric controller, photoluminescence is dynamically changed along with positive and negative voltages.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in FIG. 1, this example is in the preparation of Si-WS₂In the case of a photoelectric regulator, chemical vapor deposition is specifically utilized to deposit on the surface of the SOI substrate (consisting of Si nano-film 3 and SiO)₂Layer 4) of 30nm SiO₂An insulating layer 2. Thereafter, the single-and double-layer WS are transferred by dry transfer₂ 1 is buckled in the etching area. Suspended WS₂An electrostatic attraction force 5 is generated by the gate voltage. The top view shows the source-drain electrodes 6 added in place using maskless lithography and electron beam evaporation. Wherein the thickness of the SOI substrate and the Si nano film 3 is 200nm, and the SiO is₂Layer 4 has a thickness of 375 nm; the electrodes 6 are the source and drain, respectively, of the photo-regulator.

The following is the embodiment of using Si nano-strip to suspend two-dimensional material WS₂The preparation method of the photoelectric regulator for regulating and controlling photoluminescence comprises the following specific processes:

Step S1: preparing SOI substrate with upper layer monocrystalline silicon nano film thickness of 200nm and oxide layer thickness of 375nm, placing the SOI substrate into inductively coupled plasma chemical vapor deposition equipment, and plating with 30nm SiO₂And (3) a membrane.

In the above steps, when the thickness of the monocrystalline silicon nano-film on the upper layer of the SOI substrate is 200nm, an obvious resonance mode can be generated, and when the thickness of the oxide layer is 375nm, the resonance wavelength and WS of the nano-structure are facilitated₂Exciton peak positions overlap. Coating a layer of SiO with the thickness of 30nm on an SOI substrate₂The silicon layer may be combined with a subsequently added single-or double-layer WS₂Spaced apart, insulating to ensure application of gate voltage, while the 30nm thickness is sufficiently thin to ensure non-weakening of WS₂And interaction with the Si nano-strips.

Step S2: and etching the coated SOI substrate by using an FIB-SEM double-beam workstation with the etching beam current of 5nA, wherein two rectangular areas with the length of 20-50 mu m and the width of 5-15 mu m are etched on the coated SOI substrate, the distance between the two rectangular areas is 200-1000nm, the etching depth is 50-200nm, and Si nano-strips are formed between the two rectangular areas.

The length of the two rectangles in the above steps is preferably 20 μm-50 μm, and too long will take longer etching time, and too short will cause subsequent WS₂The transfer of (2) is difficult to align; preferably, the two rectangles have a width of 5 μm to 15 μm, too wide resulting in a subsequent transferred WS₂Failure to completely cover the etch area, too narrow may also cause subsequent WS₂The transfer of (2) is difficult to align. The width of the Si nano-strip is determined by the distance between the two rectangular areas, the distance is less than 1000nm, the Si nano-strip can be ensured to have a nano-scale size, and an obvious electromagnetic resonance mode can be generated, but the size of the Si nano-strip is not less than 200nm, and the electromagnetic mode is too weak due to the width below 200 nm. An etch depth of 50-200nm ensures that the Si layers on both sides are not completely etched away.

Step S3: let WS be₂Placing the single chip on transparent adhesive tape, repeatedly sticking and peeling to obtain thin laminated sheet, and placing WS on the adhesive tape₂Transferring the laminated sheet to the position above 1.5cm × 1.5cm PDMS substrate, repeatedly pressing with cotton swab, standing for a while, slowly peeling off the adhesive tape, placing the PDMS substrate under an optical microscope, and distinguishing single-layer WS and double-layer WS according to different layer number and different contrast₂And (4) a region.

Step S4: building a moving platform beside the microscope, and adopting a metal rod to attach WS₂The PDMS substrate of the piece is reversely arranged on the mobile platform to ensure WS₂The piece is placed over the structure to be placed, the PDMS substrate is moved down, contacts the SOI substrate and is slowly lifted up, and the WS is placed on the substrate₂The wafer is attached to the etched area.

Step S5: WS at both ends of Si nanoribbon using maskless lithography₂Upper etching the closed region, throughPlating a gold film on the etching closed area by electron beam evaporation to form a source drain electrode, and etching the two sides of the Si nano strip by the electron beam evaporation to expose the Si layer but not cover the WS₂The area of (a) is gold plated as a gate.

The photoelectric regulator obtained by the preparation method comprises a Si nano-strip, wherein WS is carried above the Si nano-strip₂WS at both ends of Si Nano-strip₂Source and drain electrodes are arranged on the silicon nano-strip, and WS is not covered on two sides of the Si nano-strip₂The region of (2) is provided with a gate.

The method for regulating and controlling the photoelectric regulator prepared by the method comprises the following steps: silver paste is coated on the source and drain electrodes and connected with thin copper wires, a power supply is connected with the thin copper wires through a lead, voltage is applied to the source and drain electrodes, and the voltage is increased or decreased by 1V from 0V to +/-10V each time. Then focusing laser with the wavelength of 514nm on the Si nano-strip, ensuring that laser beams fall on the same position in the measurement process and the size of a light spot is controlled within 1 mu m, and then enabling WS on the Si nano-strip to pass through an objective lens₂The generated photoluminescence signals are collected, the magnification of an objective lens is 50 times, the Numerical Aperture (NA) is 0.75, and the photoluminescence signals with different wavelengths are separated in space through a monochromator with 1800l/mm of grating lines in the spectrometer and projected to a CCD detector to form a spectrum.

Comparing WS according to the above-described control procedure₂Photoluminescence intensity at different positions, study of position pairs WS₂Enhancement of photoluminescence.