CN104692827B - A kind of Ag nanometers of preparation method of ball array of Ag SiO2 - Google Patents
A kind of Ag nanometers of preparation method of ball array of Ag SiO2 Download PDFInfo
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Abstract
The embodiment of the present invention provides a kind of Ag SiO2The Ag nanometers of preparation method of ball array, methods described includes：In one layer of Ag films of monocrystal silicon sample silicon chip surface hot evaporation；Monocrystal silicon sample is put into chemical vapour deposition reaction chamber and is heated to preset temperature, Ag films solid-state dehumidification is formed silver nano-grain；Reactant gas silane is passed through under the preset temperature, the silicon nano thin-film for making one layer of silver nano-grain surface uniform deposition very thin obtains Ag Si core-shell nanospheres array structures；Monocrystal silicon sample is taken out again is placed on heating in oxygen atmosphere, Si nanoshells is oxidized to SiO2；The Ag films of preset thickness are deposited with sample surfaces reheating, to form Ag SiO2Ag core-shell nanospheres array structures, as the substrate of SERS SERS.The present invention can provide a kind of Ag SiO with surface-enhanced Raman effects2The Ag nanometers of technical scheme of the preparation method of ball array.
Description
Technical field
Prepared the present invention relates to nano material and Raman spectrum detection application field, more particularly to a kind of Ag-SiO2- Ag receives
The preparation method of rice ball array.
Background technology
Raman scattering spectrum because it is to molecule and the specificity at chemical bond oscillations peak, as the powerful molecule of One function
Detection technique.SERS (SERS) has sensitivity high because of it, and quick detection can obtain normal Raman spectrum
The structural information being difficult to obtain, is widely used in the fields such as study of surfaces, biological surface science, food security.SERS is imitated
The gap between metal Nano structure should be primarily present in, i.e. " focus " (hot spot), be imitated because metal surface plasma resonates
Should, " focus " electromagnetic field nearby is greatly strengthened.Recent studies have shown that " focus " has very big increasing to SERS signal
By force, treating detection material has sensitivity very high, it might even be possible to realize Single Molecule Detection.
The current document report on active substrate preparation method is a lot.Wherein, your gold the most frequently used is based on
The SERS substrates of category nano-particle (gold nano grain, silver nano-grain), because strengthening characteristic and single point with Raman very high
The ability of son detection, obtains very extensive research.But metal nanoparticle can inevitably occur in self assembling process
Reunite, the poor reproducibility of SERS signal limits large area preparation；In order to solve the above problems, several researchers have proposed exhausted
Edge shell (such as SiO2, Al2O3) cladding the enhanced Raman scattering of metal nanoparticle (SHINERS).On the one hand very thin insulation
Shell (2-5nm) hinders the reunion between metal nanoparticle, on the other hand nor affects on the magnetic distribution of metal core, therefore
Greatly improve the reappearance of Raman signal.But, the metal nanoparticle for preparing shell isolation is a very complicated process, together
When these nano-particles need to be distributed in the substrate of noble metal, limit widely using for the structure.Additionally, with semiconductor
The development of preparation technology, certain thickness metallic film is coated as SERS active-substrate on the surface of silicon nano array structure
Method there has also been extensive research.And silicon-based nano array structure (silicon nanowires, nano-pillar, nanometer star) can by react from
Son etching (RIE), the method such as electron beam lithography (EBL) and nanosphere etching is obtained.The silicon nano-array of metallic film coating
Although structure can obtain the SERS signal of homogeneous stabilization, preparation cost is high, time-consuming, and is difficult to prepare centimetres
SERS substrates, therefore be difficult used time practical application in.
At present, some researchers successfully synthesize Fe3O4@Ag-SiO2- Au core-shell structure copolymers micro-sphere structure and Au-SiO2- Au is multiple
The nanostructured of conjunction as SERS active substrate.In the structure, very thin silica (SiO2) film is used as outer layer metal
Isolation layer between inner layer metal.By regulating and controlling SiO2The thickness of film adjusts the intermetallic spacing of ectonexine, so that most
The raising SERS signal of limits.Existing method is on the surface of metal nanoparticle using " wet method " (wet-methods)
Synthesis SiO2Film, but it is prepared by the method that thickness is uniform, less than 5 nanometers of SiO of controllable synthesis2Still it is highly difficult.Meanwhile, close
Into core-shell structure copolymer nano-particle be difficult uniformly to be distributed in solid substrate, and and substrate combination it is insecure.
The content of the invention
The embodiment of the present invention provides a kind of Ag-SiO2- Ag nanometers of the preparation method of ball array, it is a kind of with surface to provide
Strengthen the Ag-SiO of Ramam effect2- Ag nanometers of the technical scheme of the preparation method of ball array.
In order to reach above-mentioned technical purpose, a kind of Ag-SiO is the embodiment of the invention provides2- Ag nanometers of the preparation of ball array
Method, methods described includes：
In one layer of Ag films of monocrystal silicon sample silicon chip surface hot evaporation；
Monocrystal silicon sample is put into chemical vapour deposition reaction chamber and is heated to preset temperature, make Ag films solid-state dehumidification with
Form silver nano-grain；
Reactant gas silane is passed through under the preset temperature, makes one layer of very thin silicon of silver nano-grain surface uniform deposition
Nano thin-film, obtains Ag-Si core-shell nanospheres array structures；
Monocrystal silicon sample is taken out again is placed on heating in oxygen atmosphere, Si nanoshells is oxidized to SiO2；
The Ag films of preset thickness are deposited with sample surfaces reheating, to form Ag-SiO2- Ag core-shell structure copolymer nanosphere array junctions
Structure, as the substrate of SERS SERS.
Above-mentioned technical proposal has the advantages that：It is new that the embodiment of the present invention proposes dry process on a silicon substrate
Ag-SiO2-Ag core-shell structure copolymer nanosphere array structures：Using chemical vapor deposition (CVD) technology in metal nanoparticle (Ag-
NPs) surface and gap location uniformly deposit one layer of very thin silicon nano thin-film, form the spherical core-shell structure copolymer nanostructureds of Ag-Si.Examine
The silicon nano thin-film for considering deposition is easily oxidized to silica, therefore can effectively improve permeability and the metal surface of light
Field strength distribution.Now, if again in the certain thickness silver nanoparticle film of silicon nanoshell surface thermal evaporation for being formed, it is possible to make
It is standby go out Ag-SiO2- Ag core-shell structure copolymer nanosphere array structure SERS substrates.In the structure, each nanosphere is one effective
" focus ", can significantly increase the sensitivity of Raman signal.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
The accompanying drawing to be used needed for having technology description is briefly described, it should be apparent that, drawings in the following description are only this
Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, can be with
Other accompanying drawings are obtained according to these accompanying drawings.
Fig. 1 is a kind of Ag-SiO of the embodiment of the present invention2- Ag nanometers of the preparation method flow chart of ball array；
Fig. 2 is application example Ag-SiO of the present invention2- Ag core-shell structure copolymers nanometer ball array prepares schematic diagram；
Fig. 3 is the TEM figures of the single Ag-Si core-shell nanospheres of application example of the present invention, and the thickness of Si shells is about 3nm；
Fig. 4 is application example Ag-SiO of the present invention2The SEM figures of core-shell nanospheres array structure, multiplication factor is 50,000 times；
Fig. 5 is application example Ag-SiO of the present invention2Core-shell nanospheres array structure inclines 75 degree of SEM figures, multiplication factor
It is 100,000 times；
Fig. 6 is the single Ag-SiO of application example of the present invention2The TEM figures of core-shell nanospheres, SiO2The thickness of shell is about 3nm；
Fig. 7 is application example Ag-SiO of the present invention2The SEM figures of-Ag core-shell nanospheres array structures, multiplication factor is 100,000
Times；
Fig. 8 is application example Ag-SiO of the present invention2- Ag core-shell nanospheres array structure inclines 75 degree of SEM figures, times magnification
Number is 100,000 times；
Fig. 9 is application example Ag-SiO of the present invention2The TEM figures of-Ag core-shell nanospheres array structures, surface forms one layer of standard
Continuous Ag films；
Figure 10 is application example Ag films of the present invention and Ag-SiO2Cyclic voltammetric (CV) curve of core-shell nano ball array；
Figure 11 is the single Ag-SiO of application example FDTD softwares simulation of the present invention2- Ag core-shell nanospheres are made in plane wave
Field strength distribution under；
Figure 12 is application example test substance (toluene-ω-thiol) absorption of the present invention in Ag-SiO2- Ag core-shell nanospheres are not
Raman signal during with position；
Figure 13 is that application example test substance (rhodamine 6G) of the present invention is adsorbed in optimal SERS substrates and do not had respectively
Raman signal comparison diagram during the planar substrates of standby enhancement effect；
Figure 14 is application example rhodamine 6G (10 of the present invention-6During M) as probe molecule absorption in SERS active-substrate,
The distribution map of the Raman signal of the diverse location (100 points) obtained under 633nm wavelength；
Figure 15 is the rhodamine 6G (10 of application example various concentrations of the present invention-9M-10-13M) exist as probe molecule absorption
When in SERS substrates, the Raman curve map for obtaining.
Specific embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Site preparation is described, it is clear that described embodiment is only a part of embodiment of the invention, rather than whole embodiments.It is based on
Embodiment in the present invention, it is every other that those of ordinary skill in the art are obtained under the premise of creative work is not made
Embodiment, belongs to the scope of protection of the invention.
Large area, highly dense is directly formed in smooth substrate using solid-state dehumidification (solid state dewetting)
The metal nanoparticle of degree can be effectively improved the binding ability between metallic and substrate.Between size, the particle of nano-particle
Gap depend on metallic film thickness and annealing temperature and annealing time, this simple method be inexpensive, big face
Product prepares SERS active substrates there is provided possible.Based on this we have proposed the new Ag-SiO of dry process on a silicon substrate2-
Ag core-shell structure copolymer nanosphere array structures.Using chemical vapor deposition (CVD) technology metal nanoparticle (Ag-NPs) surface and
One layer of very thin silicon nano thin-film is uniformly deposited at gap, the spherical nanometer nuclear shell nano-structures of Ag-Si are formed.Silicon in view of deposition is received
Rice film is easily oxidized to silica, therefore can effectively improve the permeability of light and the field strength distribution of metal surface.This
When, if again in the certain thickness silver nanoparticle film of silicon nanoshell surface thermal evaporation for being formed, it is possible to prepare Ag-SiO2-
Ag core-shell structure copolymer nanosphere array structure SERS substrates.In the structure, each nanosphere is one effective " focus ", can be notable
Strengthen the sensitivity of Raman signal.
To fill up blank prepared by existing one-dimensional silicon nanostructure, the invention reside in offer one kind combination chemical vapor deposition
(CVD) technique and thermal evaporation coating technique, prepare a kind of Ag-SiO with surface-enhanced Raman effects2- Ag core-shell structure copolymer nanospheres
Array structure.The method prepare SERS substrates have sensitivity very high, preparation process is simple, Raman signal favorable reproducibility,
Can large area preparation.
As shown in figure 1, being a kind of Ag-SiO of the embodiment of the present invention2- Ag nanometers of the preparation method flow chart of ball array, it is described
Method includes：
101st, in one layer of Ag films of monocrystal silicon sample silicon chip surface hot evaporation；
102nd, monocrystal silicon sample is put into chemical vapour deposition reaction chamber and is heated to preset temperature, pass through Ag films solid
State dehumidification forms silver nano-grain；
103rd, reactant gas silane is passed through under the preset temperature, makes one layer of silver nano-grain surface uniform deposition very thin
Silicon nano thin-film, obtain Ag-Si core-shell nanospheres array structures；
104th, monocrystal silicon sample is taken out again and is placed on heating in oxygen atmosphere, Si nanoshells is oxidized to SiO2；
105th, the Ag films of preset thickness are deposited with sample surfaces reheating, to form Ag-SiO2- Ag core-shell structure copolymers nanometer spherical array
Array structure, as the substrate of SERS SERS.
Ag-SiO2-Ag nanospheres array structure can be as the substrate of SERS (SERS), when a small amount of to be checked
Material absorption is surveyed in substrate surface, can great enhancing material Raman scattering signal.
Preferably, before the step 101, using supersonic cleaning machine by monocrystal silicon sample successively with deionized water, acetone,
Deionized water is cleaned by ultrasonic, and ultrasonic power is 180W, and frequency is 40KHz, and ultrasonic time is respectively 10 minutes.Preferably,
The monocrystal silicon sample is single-sided polishing, and the intrinsic silicon of the p-type, n-type silicon or undoped p of doping, methods described also includes：Will
It is 4 that monocrystal silicon sample silicon chip after ultrasonic cleaning places into volume ratio:Ten minutes are soaked in 1 concentrated sulfuric acid and hydrogen peroxide to remove
Oxide on surface, is cleaned with deionized water；Finally silicon chip is put into 5% hydrofluoric acid and soaked five minutes, make silicon chip surface shape
Into Si -- H bond.
The step 101 includes：Monocrystal silicon sample silicon chip surface is placed in hot evaporation in high vacuum thermal evaporation coating system
One layer of Ag films.
Hot evaporation deposited metal film is preferably used in the step 101.Compared with other plated film modes, using thermal evaporation
Mode plated film have plated film uniform, controllable-rate, the advantages of prepare simple, cost is relatively low.In general, hot evaporation speed is got over
Slow and sample stage rotary speed is more reasonable, and the compactness of metallic film is better, and roughness is lower.
Pressure is evacuated to 3 × 10 in thermal evaporation chamber in the step 101-4Pa, the speed of thermal evaporation is preferablySample
Platform velocity of rotation is preferably 20r/min, and the thickness of metallic film is preferably 15nm.
The limit heating-up temperature of CVD reaction cavities is 1050 DEG C in the step 102, and smooth silicon chip table is deposited at room temperature
The metallic film in face is in stable state.When sample is heated to uniform temperature anneals, the metallic film in half stable state is in base
Plate surface is broken, and the little particle of nanoscale is formed, here it is the process of solid-state dehumidification (dewetting).The chi of nano particle
Very little, density is relevant with annealing temperature and annealing time.Generally, when the timing of thickness of metal film one, annealing temperature is increased
With extension annealing time, the size of the metallic particles of formation is bigger, and spacing is wider between particle, and grain density is lower.
The annealing temperature preferably used in the step 102 is 540 DEG C, is incubated 10 minutes at this temperature, is now obtained
The average diameter of Nano silver grain is 73nm.
Reaction chamber internal pressure is strong in the step 102 is scheduled on 10Torr, and the flow of hydrogen is preferably 40SCCM.Heated
Hydrogen is passed through in journey, the oxide on Ag films surface can be effectively reduced.
Maintain this temperature-resistant in the step 103, reacting gas (5%SiH is passed through in reaction chamber4) and adjust hydrogen
Flow, maintain chamber in invariablenes pressure of liquid.Now silane pyrolysis at this temperature, silicon atom is uniformly deposited on the table of Nano silver grain
Face forms the spherical core-shell structure copolymer nanostructureds of Ag-Si.The thickness reaction time of silicon nanoshell is directly proportional.
The flow of reacting gas (silane) is preferably 20SCCM in the step 103, and the flow of hydrogen is preferably 20SCCM,
In 10Torr, growth time is preferably 3 minutes invariablenes pressure of liquid.
In the step 104, monocrystal silicon sample is taken out and is placed in heating thermal station, be heated in clean air
100 DEG C and be incubated 5 hours, the silicon nano thin-film on surface is completely oxidized to silica, obtain Ag-SiO2Core-shell nano chou
Structure.
In the step 105, the Ag films that preset thickness is deposited with monocrystal silicon sample surface reheating, to form Ag-
SiO2The active substrate of-Ag core-shell structure copolymer nanosphere array structures, including：Using thermal evaporation apparatus in monocrystal silicon sample surface reheating
The Ag films of preset thickness are deposited with, to form Ag-SiO2- Ag core-shell nanospheres array structures；The Ag film thicknesses of structure deposition
It is 10nm, the speed of thermal evaporation isSample stage slewing rate is 20r/min；By the Ag-SiO2- Ag core-shell structure copolymers nanometer
The active substrate that spherical array array structure is detected as SERS, with the Raman signal of detection probe molecule, including：Substrate is immersed in and is contained
In having the aqueous solution of rhodamine 6G, the concentration of aqueous solution 10-6~10-13M, soak time is to be taken out after 1 hour, makes testing molecule
Absorption is on the surface of substrate；Active substrate is placed under Raman spectrometer laser and is irradiated, optical maser wavelength selection 633nm, power choosing
It is selected as 0.24mW.
The embodiment of the present invention has the following advantages that：
(1) prepare simply, can large area preparation.By hot evaporation and chemical gaseous phase depositing process, 5cm can be once prepared
The active substrate of × 5cm sizes.And when carrying out Raman detection, it is only necessary to cleavage goes out the sample of 0.5cm × 0.5cm and enters from sample
Row test.Therefore, it can once prepare, be used for multiple times.
(2) outer layer nanoshell is uniform, fine and close, and the thickness of shell can realize accurate control by controlling the CVD growth time.
(3)Ag-SiO2- Ag core-shell structure copolymer nanosphere array structures, each nanosphere is an effective Raman enhancing " heat
Point ", can effectively improve SERS signal.
(4) the SERS substrates prepared have uniform, and signal reproducibility is good, the advantages of detectable limit is high.Meet theory to grind
The need for studying carefully with commercial applications.
The embodiment of the present invention is described in detail below in conjunction with application example and Fig. 2-Figure 15：
Embodiment one
A kind of method that surface Raman enhancement active substrate is prepared based on chemical vapor deposition is present embodiments provided, is prepared
As shown in Fig. 2 (a) one layer of Ag film of hot evaporation on smooth silicon substrate, (b) heating anneal in CVD reaction chambers makes silicon to flow
Substrate surface forms Ag nano-particles, and reacting gas is passed through in (c) reaction chamber, obtains Ag-Si core-shell nano ball arrays, and (d) will
Sample takes out and is placed on heating in oxygen atmosphere, obtains Ag-SiO2Core-shell nano ball array, one layer of Ag film of (e) hot evaporation, obtains
To Ag-SiO2The SERS substrates of-Ag core-shell nano ball arrays, (f) material absorption to be detected carries out Raman inspection in SERS substrates
Survey.
Technical scheme is further described below.
Pre-treatment：The step of according to deionized water, acetone, deionized water, is cleaned by ultrasonic 2.5cm × 5cm silicon chips, ultrasonic work(
Rate is 180W, and the ultrasonic cleaning time is respectively 10min.Then it is 30% with the concentrated sulfuric acid and mass fraction that mass fraction is 98%
Hydrogen peroxide with volume ratio 4:Cleaning 10min, deionized water rinsing, nitrogen drying are aoxidized in 1 mixed liquor.Processed through hydroxylating
Silicon chip be positioned in the HF solution that mass fraction is 5%, make silicon chip surface formed Si -- H bond.
Hot evaporation metallic film：The silicon chip that the surface that will be cleaned up forms Si -- H bond is put into hot evaporation equipment.Work as heat
Evaporation chamber vacuum is evacuated to 2.5 × 10-4After Pa, silver is melted into liquid in slow high current to boat.Now adjust electric current to steaming
Plating rate stabilization existsThen sample baffle plate is opened after regulation sample tray rotating speed 20r/min.Hot evaporation silver film thickness is
15nm。
Ag-SiO2It is prepared by nanostructured：The silicon chip of hot evaporation certain thickness Ag films is placed into chemical vapor depsotition equipment
In vacuum cavity, 9 × 10 are evacuated to cavity-7Torr, after be passed through high pure nitrogen to chamber pressure stabilization in 10Torr.This
When, start to be slowly heated cavity and keep being passed through hydrogen flowing quantity for 40SCCM.When cavity being heated into 540 DEG C in 30 minutes,
And 10min is incubated at such a temperature to obtain silver nano-grain.Then maintain the flow of hydrogen constant at such a temperature and be passed through
Reacting gas (silane 20SCCM), the silicon atom that silane cracking is obtained under high temperature is deposited in substrate surface, in silver after growth 3min
Nano grain surface deposits one layer of very thin Si nanoshell, as shown in Figure 3.After growth terminates, sample is taken out and places dry
100 DEG C are heated in air and 5 hours are incubated, Ag-SiO is obtained2Core-shell nanospheres array structure, as shown in Figure 4.Fig. 5 is this
Invention application example Ag-SiO2The spherical array structure of core-shell nano inclines 75 degree, amplifies 100,000 times of SEM figures.Fig. 6 is single
Ag-SiO2The TEM figures of nanosphere, outer layer SiO2The thickness of nanoshell is about 3nm.
Ag-SiO2It is prepared by-Ag core-shell nanos ball array：The Ag-SiO obtained after CVD reactions2Core shell structure does not simultaneously have drawing
Graceful enhancement effect, in order to obtain SiO2The SERS substrates of nanometer thickness of the shell regulation and control, in addition it is also necessary to cover layer of metal film on surface.
Therefore, using thermal evaporation coating system in Ag-SiO2Again one layer of Ag film is deposited with the basis of core shell structure.Technological parameter with
It is above-mentioned consistent, evaporation rateThe Raman signal that Ag film thicknesses are obtained when being 10nm is most strong, SEM such as Fig. 7-Fig. 8：Fig. 7 is
Ag-SiO is obtained after one layer of Ag films of application example hot evaporation of the present invention2The SEM figures of-Ag core-shell nanospheres array structures, amplify
Multiple is 50,000 times.Fig. 8 is application example Ag-SiO of the present invention2- Ag core-shell nanospheres array structure inclines 75 degree, amplifies 100,000
SEM figures again.Fig. 9 is application example Ag-SiO of the present invention2The transmission electron microscope of-Ag core-shell nanospheres array structures
(TEM) figure, as can be seen from the figure by having obtained one layer of quasi-continuous Ag nano thin-film after thermal evaporation plated film.
The performance characterization of nanometer nuclear shell nano-structure：Figure 10 is the cyclic voltammetry curve figure that the embodiment of the present invention is obtained, with electricity
Chem workstation is respectively to two samples before and after CVD reactions：Ag films on (i) silicon substrate；(ii) Ag- on silicon substrate
SiO2Core-shell nano ball array, is circulated volt-ampere test.From Ag-AgCL electrodes as reference electrode, Pt electrodes are to electricity
Pole, used as working electrode, NaOH (1Mol/L) is as electrolyte for highly doped silicon chip.As illustrated, when Ag films directly with electricity
When solution liquid is contacted, two oxidation peak (Ag-Ag are obtained2) and a reduction peak (AgO-Ag) O--AgO.But, work as external sheath
One layer of very thin SiO2Do not occur oxidation, the Ag nano-particles of the presence of reduction peak, i.e. nanoshell isolation and electricity during nanoshell
Solve the contact of liquid.Illustrate to be reacted by CVD and obtained one layer of uniform, fine and close nanoshell.
SERS substrate performance characterizations：Figure 11 is the single Ag-SiO of finite element difference time domain analysis (FDTD) software simulation2-
Electromagnetic field field intensity map of the Ag core-shell nanospheres under plane wave effect, theoretically demonstrates Ag-SiO2- Ag nucleocapsids are received
Rice structure has obvious surface plasmon resonance effect, so as to Raman signal can effectively be strengthened.Accompanying drawing 12 is determinand
The Raman signal that matter (toluene-ω-thiol) absorption is obtained in different nanostructured surfaces, testing molecule absorption is demonstrated from laboratory
At the outer surface of silver nanoparticle film with maximum SERS effects.Accompanying drawing 13 is that rhodamine 6G is adsorbed in SERS substrates respectively
(10-9) and the planar substrates (2 × 10 without Raman enhancement effect M-3M the Raman signal comparison diagram on), illustrates SERS signal
Mostly come from Ag-SiO2- Ag nanometer nuclear shell nano-structures.Accompanying drawing 14 is embodiment of the present invention Ag-SiO2- Ag core-shell nano ball arrays
SERS substrates detection rhodamine 6G (10-6When M), line scans the Raman curve distribution in 100 sites that each 4 μm intervals obtain
Figure, illustrates that the SERS substrates have preferable signal homogeneity and reappearance.Accompanying drawing 15 is application example SERS substrates of the present invention
Upper detection various concentrations rhodamine 6G (10-9M-10-13M Raman curve map), illustrates based on Ag-SiO2- Ag core-shell nano spherical arrays
The SERS substrate detectable concentration limit of array structure can reach 10-12M。
Embodiment two：
A kind of method that surface Raman enhancement active substrate is prepared based on chemical vapor deposition is present embodiments provided, is prepared
As shown in Fig. 2 (a) one layer of Ag film of hot evaporation on smooth silicon substrate, (b) heating anneal in CVD reaction chambers makes silicon to flow
Substrate surface forms Ag nano-particles, and reacting gas is passed through in (c) reaction chamber, obtains Ag-Si core-shell nano ball arrays, and (d) will
Sample takes out and is placed on heated oxide in pure air, obtains Ag-SiO2Core-shell nano ball array, (e) hot evaporation layer of Au is thin
Film, obtains Ag-SiO2The SERS substrates of-Au core-shell nano ball arrays, (f) material absorption to be detected is drawn in SERS substrates
Graceful detection.
Technical scheme is further described below.
Pre-treatment：The step of according to deionized water, acetone, deionized water, is cleaned by ultrasonic 2.5cm × 5cm silicon chips, ultrasonic work(
Rate is 180W, and the ultrasonic cleaning time is respectively 10min.Then it is 30% with the concentrated sulfuric acid and mass fraction that mass fraction is 98%
Hydrogen peroxide with volume ratio 4:Cleaning 10min, deionized water rinsing, nitrogen drying are aoxidized in 1 mixed liquor.Processed through hydroxylating
Silicon chip be positioned in the HF solution that mass fraction is 5%, make silicon chip surface formed Si -- H bond.
Hot evaporation metallic film：The silicon chip that the surface that will be cleaned up forms Si -- H bond is put into hot evaporation equipment.Work as heat
Evaporation chamber vacuum is evacuated to 2.5 × 10-4After Pa, silver is melted into liquid in slow high current to boat.Now adjust electric current to steaming
Plating rate stabilization existsThen sample baffle plate is opened after regulation sample tray rotating speed 20r/min.Hot evaporation silver film thickness is
15nm。
Ag-SiO2It is prepared by nanostructured：The silicon chip of hot evaporation certain thickness Ag films is placed into chemical vapor depsotition equipment
In vacuum cavity, 9 × 10 are evacuated to cavity-7Torr, after be passed through high pure nitrogen to chamber pressure stabilization in 10Torr.This
When, start to be slowly heated cavity and keep being passed through hydrogen flowing quantity for 40SCCM.When cavity being heated into 540 DEG C in 30 minutes,
And 10min is incubated at such a temperature to obtain silver nano-grain.Then maintain the flow of hydrogen constant at such a temperature and be passed through
Reacting gas (silane 20SCCM), the silicon atom that silane cracking is obtained under high temperature is deposited in substrate surface, in silver after growth 3min
Nano grain surface deposits one layer of very thin Si nanoshell, as shown in Figure 3.After growth terminates, sample is taken out and places dry
Heated oxide 5 hours, obtain Ag-SiO in air2Nanosphere nucleocapsid array structure, as shown in Figure 4.Fig. 5 is that present invention application is real
Example Ag-SiO2The spherical array structure of core-shell nano inclines 75 degree, amplifies 100,000 times of SEM figures.Fig. 6 is single Ag-SiO2Nanosphere
TEM figure, outer layer SiO2The thickness of nanoshell is about 3nm.
Ag-SiO2It is prepared by-Au core-shell nanos ball array：The Ag-SiO obtained after CVD reactions2Core shell structure does not simultaneously have drawing
Graceful enhancement effect, in order to obtain SiO2The SERS substrates of nanoshell regulation and control, in addition it is also necessary to cover layer of metal film on surface.Cause
This, using thermal evaporation coating system in Ag-SiO2Again layer of Au film is deposited with the basis of core shell structure.Technological parameter with it is upper
State consistent, evaporation rateDo not repeating.
The performance characterization of nanometer nuclear shell nano-structure：With electrochemical workstation respectively to two sample (silicon before and after CVD reactions
Ag films on substrate；Ag-SiO on silicon substrate2Core-shell nano ball array) it is circulated volt-ampere test.Ag-AgCL electrodes are made
It is reference electrode, Pt electrodes are that, to electrode, from highly doped silicon chip as working electrode, NaOH (1Mol/L) is as electrolysis
Liquid.As illustrated, when Ag films directly with electrolyte contacts when, obtain two oxidation peak (Ag-Ag2O--AgO) gone back with one
Parent peak (AgO-Ag).But, as one layer of very thin SiO of external sheath2Do not occur oxidation, reduction peak, i.e. nanometer during nanoshell
The contact of the Ag nano-particles with electrolyte of the presence isolation of shell.Illustrate to be reacted by CVD and obtained one layer and uniform, fine and close receive
Rice shell.
SERS substrate performance characterizations：The single Ag-SiO simulated with finite element difference time domain analysis (FDTD) software2-Au
Electromagnetic field field intensity map of the core-shell nanospheres under plane wave effect, theoretically proves Ag-SiO2- Au nanometer nuclear shell nano-structures
With obvious surface plasmon resonance effect, so as to Raman signal can effectively be strengthened.And experimentally prove to be measured point
Son absorption is at the outer surface of Au nano thin-films with maximum SERS effects.Toluene-ω-thiol is adsorbed respectively as probe molecule
In SERS substrates (10-8) and the planar silicon substrate (4 × 10 without Raman enhancement effect M-3M on), its Raman signal is detected,
Illustrate that SERS effects are mainly derived from Ag-SiO2- Au nanometer nuclear shell nano-structures.Ag-SiO2The SERS bases of-Au core-shell nano ball arrays
Detect toluene-ω-thiol (10 in bottom-8When M), line scans the Raman curve distribution figure in 100 sites of each 4 micron pitch acquisition, says
The bright SERS substrates have preferable signal homogeneity and reappearance.Detect different dense toluene-ω-thiols (10-8M~10-12M)
Raman curve map, illustrates based on Ag-SiO2The SERS substrates of-Au core-shell nanospheres array structures have detectable limit higher.
Above-described specific embodiment, has been carried out further to the purpose of the present invention, technical scheme and beneficial effect
Describe in detail, should be understood that and the foregoing is only specific embodiment of the invention, be not intended to limit the present invention
Protection domain, all any modification, equivalent substitution and improvements within the spirit and principles in the present invention, done etc. all should include
Within protection scope of the present invention.
Claims (8)
1. a kind of Ag-SiO2- Ag nanometers of the preparation method of ball array, it is characterised in that methods described includes：
In one layer of Ag films of monocrystal silicon sample silicon chip surface hot evaporation；
Monocrystal silicon sample is put into chemical vapour deposition reaction chamber and is heated to preset temperature, form Ag films solid-state dehumidification
Silver nano-grain；
Reactant gas silane is passed through under the preset temperature, makes the silicon nanometer that one layer of silver nano-grain surface uniform deposition is very thin
Film, obtains Ag-Si core-shell nanospheres array structures；
Monocrystal silicon sample is taken out again is placed on heating in oxygen atmosphere, Si nanoshells is oxidized to SiO2, including：By monocrystalline silicon
Sample is taken out and is placed in heating thermal station, and 100 DEG C are heated in clean air and 5 hours are incubated, and makes the silicon nanometer on surface
Film is completely oxidized to silica, obtains Ag-SiO2Core-shell structure copolymer nanometer spherical structure；
The Ag films of preset thickness are deposited with sample surfaces reheating, to form Ag-SiO2- Ag core-shell structure copolymer nanosphere array structures, with
As the substrate of SERS SERS, including：Using thermal evaporation apparatus, on monocrystal silicon sample surface, hot evaporation is pre- again
If the Ag films of thickness, to form Ag-SiO2- Ag core-shell structure copolymer nanosphere array structures；The structure deposition Ag film thicknesses be
10nm, the speed of thermal evaporation isSample stage slewing rate is 20r/min；By the Ag-SiO2- Ag core-shell structure copolymer nanospheres
The active substrate that array structure is detected as SERS, with the Raman signal of detection probe molecule, including：By substrate be immersed in containing
In the aqueous solution of rhodamine 6G, the concentration of aqueous solution 10-6~10-13M, soak time is to be taken out after 1 hour, inhales testing molecule
It is attached to the surface of substrate；Active substrate is placed under Raman spectrometer laser and is irradiated, optical maser wavelength selection 633nm, power selection
It is 0.24mW.
2. method as claimed in claim 1, it is characterised in that described in one layer of Ag films of monocrystal silicon sample silicon chip surface hot evaporation
Before,
Monocrystal silicon sample is cleaned by ultrasonic with deionized water, acetone, deionized water successively using supersonic cleaning machine, ultrasonic work(
Rate is 180W, and frequency is 40KHz, and ultrasonic time is respectively 10 minutes.
3. method as claimed in claim 2, it is characterised in that the monocrystal silicon sample is single-sided polishing, the p-type of doping, N-shaped
The intrinsic silicon of silicon or undoped p, methods described also includes：
It is 4 that monocrystal silicon sample silicon chip after ultrasonic cleaning is placed into volume ratio:Soaked ten minutes in 1 concentrated sulfuric acid and hydrogen peroxide
To remove oxide on surface, cleaned with deionized water；Finally silicon chip is put into 5% hydrofluoric acid and soaked five minutes, make silicon chip
Surface forms Si -- H bond.
4. method as claimed in claim 1, it is characterised in that described thin in one layer of silver of monocrystal silicon sample silicon chip surface hot evaporation
Film, including：
Monocrystal silicon sample silicon chip surface is placed in one layer of Ag films of hot evaporation in high vacuum thermal evaporation coating system.
5. method as claimed in claim 4, it is characterised in that in the high vacuum thermal evaporation coating system, thermal evaporation chamber internal pressure
It is evacuated to 3 × 10 by force-4Pa, the speed of thermal evaporation isSample stage velocity of rotation is 20r/min, and the thickness of metallic film is
15nm。
6. method as claimed in claim 1, it is characterised in that the limit heating-up temperature in the chemical vapour deposition reaction chamber is
1050 DEG C, the metallic film that smooth silicon chip surface is deposited at room temperature is in stable state；The annealing temperature for using is 540 DEG C,
10 minutes are incubated under the annealing temperature, the average diameter of the Nano silver grain for now obtaining is 73nm.
7. method as claimed in claim 6, it is characterised in that chemical vapour deposition reaction chamber internal pressure is strong to be scheduled on
10Torr, the flow of hydrogen is 40SCCM；Hydrogen is passed through in heating process, to reduce the oxide on Ag films surface.
8. method as claimed in claim 1, it is characterised in that described to be passed through reactant gas silane under the preset temperature, makes
The very thin silicon nano thin-film of one layer of silver nano-grain surface uniform deposition, obtains Ag-Si core-shell nanospheres array structures, including：
Maintain the preset temperature constant, 5%SiH is passed through in chemical vapour deposition reaction chamber4Reacting gas and adjust hydrogen
Flow, maintain invariablenes pressure of liquid in chemical vapour deposition reaction chamber；Now silane pyrolysis under the preset temperature, silicon atom is uniform
Be deposited on Nano silver grain surface formed the spherical core-shell structure copolymer nanostructureds of Ag-Si；The flow of reactant gas silane is
20SCCM, the flow of hydrogen is 20SCCM, and in 10Torr, growth time is 3 minutes to invariablenes pressure of liquid.
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| CN113533295A (en) * | 2021-06-01 | 2021-10-22 | 山东师范大学 | Based on ReS2Three-dimensional SERS substrate and preparation method and application thereof |
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