CN104217931A - Graphene doping method and doped graphene - Google Patents
Graphene doping method and doped graphene Download PDFInfo
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- CN104217931A CN104217931A CN201310206633.3A CN201310206633A CN104217931A CN 104217931 A CN104217931 A CN 104217931A CN 201310206633 A CN201310206633 A CN 201310206633A CN 104217931 A CN104217931 A CN 104217931A
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 220
- 229910021389 graphene Inorganic materials 0.000 title claims abstract description 218
- 238000000034 method Methods 0.000 title claims abstract description 70
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims abstract description 28
- 239000004926 polymethyl methacrylate Substances 0.000 claims abstract description 28
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 36
- 229910052710 silicon Inorganic materials 0.000 claims description 35
- 239000010703 silicon Substances 0.000 claims description 35
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 34
- 235000012239 silicon dioxide Nutrition 0.000 claims description 18
- 239000000377 silicon dioxide Substances 0.000 claims description 18
- 238000000386 microscopy Methods 0.000 claims description 9
- 230000003321 amplification Effects 0.000 claims description 7
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 7
- 239000002184 metal Substances 0.000 claims description 6
- 230000008676 import Effects 0.000 claims description 5
- 238000011065 in-situ storage Methods 0.000 abstract description 5
- 230000008901 benefit Effects 0.000 abstract description 4
- 239000000523 sample Substances 0.000 description 18
- 238000004528 spin coating Methods 0.000 description 12
- 230000008569 process Effects 0.000 description 8
- 239000000243 solution Substances 0.000 description 7
- RDOXTESZEPMUJZ-UHFFFAOYSA-N anisole Chemical class COC1=CC=CC=C1 RDOXTESZEPMUJZ-UHFFFAOYSA-N 0.000 description 6
- 239000002904 solvent Substances 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 230000002459 sustained effect Effects 0.000 description 5
- 230000032258 transport Effects 0.000 description 5
- 239000002390 adhesive tape Substances 0.000 description 4
- MVPPADPHJFYWMZ-UHFFFAOYSA-N chlorobenzene Chemical compound ClC1=CC=CC=C1 MVPPADPHJFYWMZ-UHFFFAOYSA-N 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 238000002347 injection Methods 0.000 description 4
- 239000007924 injection Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 229910002804 graphite Inorganic materials 0.000 description 3
- 239000010439 graphite Substances 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 238000005381 potential energy Methods 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- 239000004793 Polystyrene Substances 0.000 description 2
- 125000004429 atom Chemical group 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000002800 charge carrier Substances 0.000 description 2
- MVPPADPHJFYWMZ-IDEBNGHGSA-N chlorobenzene Chemical group Cl[13C]1=[13CH][13CH]=[13CH][13CH]=[13CH]1 MVPPADPHJFYWMZ-IDEBNGHGSA-N 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
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- 230000005611 electricity Effects 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- UZKWTJUDCOPSNM-UHFFFAOYSA-N methoxybenzene Substances CCCCOC=C UZKWTJUDCOPSNM-UHFFFAOYSA-N 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 238000000053 physical method Methods 0.000 description 2
- 229920002223 polystyrene Polymers 0.000 description 2
- 239000012488 sample solution Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 150000007984 tetrahydrofuranes Chemical group 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 150000001721 carbon Chemical group 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/22—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities
- H01L21/2205—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities from the substrate during epitaxy, e.g. autodoping; Preventing or using autodoping
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/16—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only elements of Group IV of the Periodic System
- H01L29/1606—Graphene
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/66007—Multistep manufacturing processes
- H01L29/66015—Multistep manufacturing processes of devices having a semiconductor body comprising semiconducting carbon, e.g. diamond, diamond-like carbon, graphene
- H01L29/66037—Multistep manufacturing processes of devices having a semiconductor body comprising semiconducting carbon, e.g. diamond, diamond-like carbon, graphene the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
- H01L29/66045—Field-effect transistors
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- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
- H01L29/76—Unipolar devices, e.g. field effect transistors
- H01L29/772—Field effect transistors
- H01L29/78—Field effect transistors with field effect produced by an insulated gate
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Abstract
The invention discloses a graphene doping method and doped graphene obtained by using the method. The method comprises the following steps: forming a polymethyl methacrylate film on the surface graphene layer of a graphene device; selecting a graphene region needing to be doped; and introducing charges into the selected graphene region through the conductive needle point of an atomic force microscope for doping. The method according to the invention has the advantages that graphene doping can be realized in situ; the doping region can be of various shapes; the doping concentration is controllable and continuously-adjustable; and an intrinsic sample can be doped effectively, and a doped sample can be de-doped.
Description
Technical field
The present invention relates to method and the doped graphene of the doping of a kind of Graphene, particularly, relate to a kind of original position electrostatic injection mode that utilizes and realize the controllable doped method of Graphene, and by doped graphene that the method obtains.
Background technology
Graphene by after the report such as the professor An Deliehaimu of Univ Manchester UK, caused the extensive concern of scientist from 2004 with the performance of its uniqueness, predictedly will cause revolutionary variation in a lot of fields.Graphene to be a kind of energy gap be zero semiconductor, have the carrier mobility of higher than silicon 100 times, at room temperature have micron order free path and large coherence length, therefore it is the ideal material of nm circuit.But Graphene is in application aspect, is also faced with an important challenge, is exactly how to realize its controllable function, in order to give full play to its advantageous property, effective functionalization must be carried out to Graphene.Graphene doping is one of important channel realizing graphene functionalized, is a kind of effective means of regulation and control Graphene electricity and optical property, and the Graphene after doping has because of it focus that huge application prospect has become researcher's concern.
At present, mainly contain following two kinds of modes to regulate carrier type in Graphene and concentration, thus realize the Effective Doping to Graphene.
Chemical doping: chemical doping changes the most frequently used method of semiconducting electrical conductivity matter.Research finds, in the Graphene of steady chemical structure, the impurity element that induces one replaces the control that one or more carbon atom can realize conductive characteristic.Such as, utilize chemical vapour deposition technique directly to adulterate the elements such as B, N or atomic group, the p-type to intrinsic Graphene or N-shaped doping can be realized, by carrying out the concentration of the charge carrier after controlled doping in Graphene to the adjustment of doping content.Chemical doping is mainly divided into intercalation or the large class of adsorption two in molecule.Embed foreign atom between its Middle molecule internal layer and can form stable defect sturcture, adsorption foreign atom then can avoid the change causing graphene-structured.Certainly, the conduction type after chemical doping in Graphene and conductivity relevant with doping content with the kind of dopant.But based on the method, the accurate control that cannot realize carrier concentration of adulterating is carried out to Graphene, the more important thing is that this method can introduce the random scattering source of a large amount of distributions in Graphene, thus after causing doping, graphene carrier mobility sharply declines.
Physical doping: physical doping utilizes physical method, not destroying on the basis of graphene-structured, adulterates to it.Method the most frequently used at present regulates type and the concentration of the charge carrier of inducing in Graphene by controlling Applied gate voltages, thus it is controllable doped to realize Graphene.Compared with chemical doping method, physical doping can avoid the uncontrollable shortcoming of dosed carrier concentration, the more important thing is that it can not introduce fault of construction in Graphene, is carrying out the loss that can not cause its mobility in controllable doped process to Graphene.Utilizing physical method to Graphene doping at present mainly through constructing grid to realize, can be divided into backgate and top grid according to the different grid of structure, is all that polarity and size by changing grid voltage regulates carrier type in Graphene and concentration.Backgate regulates directly with SiO
2/ Si substrate is grid, but this mode cannot realize adulterating to the local of Graphene.Top grid regulate and need to utilize micro fabrication and depositing operation to construct grid at Graphene upper surface, realize the physical doping to Graphene specific region by the position of control gate and size.But this doping method will be achieved by the mode of constructing top grid, and manufacturing process is comparatively complicated, and relative energy consumption is comparatively large, is unsuitable for the application of industrial quarters and popularizes.
Summary of the invention
In view of above-mentioned problems of the prior art, the method that the invention provides the doping of a kind of new Graphene and the doped graphene obtained by the method, method according to the present invention has the following advantages: can realize Graphene doping in situ; The various shapes of doped region; Controlled and the continuously adjustabe of doping content; Not only can Effective Doping intrinsic sample, doping can also be moved back to the sample adulterated.
The present inventor is found by research repeatedly, by forming polymethyl methacrylate film on the surperficial graphene layer of graphene device, and import electric charge by the conductive pinpoint of atomic force microscope to Graphene region, a kind of Graphene doping method with above-mentioned advantage can be provided, and doping can be moved back to the sample adulterated, thus complete the present invention.
That is, the invention provides the method for a kind of Graphene doping, wherein, the method comprises the following steps:
1) on the surperficial graphene layer of graphene device, polymethyl methacrylate film is formed;
2) the Graphene region needing doping is selected;
3) import electric charge by the conductive pinpoint of atomic force microscope to selected Graphene region to adulterate.
The present invention also provides a kind of doped graphene, and wherein, this doped graphene is prepared by above-mentioned method.
According to method of the present invention, it has the following advantages:
(1) Graphene doping can be realized in situ;
(2) size of doped region and position controlled, the various shapes of doped region;
(3) the controlled and continuously adjustabe of doping content;
(4) not only can Effective Doping intrinsic sample, doping can also be moved back to the sample adulterated;
(5) adulterate with conventional physical compared with the program do not need grid, so implementation procedure is simple and power consumption is little.
Accompanying drawing explanation
Accompanying drawing is used to provide a further understanding of the present invention, and forms a part for specification, is used from explanation the present invention, but is not construed as limiting the invention with embodiment one below.In the accompanying drawings:
Fig. 1 is the schematic diagram representing electrostatic injection mode doped graphene.
Fig. 2 is the transfer characteristic curve of the graphenic surface potential energy diagram after local doping and the graphene device before and after doping in embodiment 2, wherein, (a) in Fig. 2 is the transfer characteristic curve of the graphene device before and after doping for the graphenic surface potential energy diagram after local doping, (b) in Fig. 2.
Fig. 3 is the transfer characteristic curve of the graphene device in embodiment 3 before and after overall situation doping.
Description of reference numerals
1 silicon layer
2 silicon dioxide layers
3 Graphenes
4 polymethyl methacrylate films
5 electrodes
6 conductive pins
Embodiment
Below the specific embodiment of the present invention is described in detail.Should be understood that, embodiment described herein, only for instruction and explanation of the present invention, is not limited to the present invention.
The method of Graphene doping provided by the invention comprises the following steps:
1) on the surperficial graphene layer of graphene device, polymethyl methacrylate film is formed;
2) the Graphene region needing doping is selected;
3) import electric charge by the conductive pinpoint of atomic force microscope to selected Graphene region to adulterate.
Below by accompanying drawing, the method that Graphene of the present invention adulterates is described in detail.
Fig. 1 is the schematic diagram representing electrostatic injection mode doped graphene.In the present invention, described graphene device comprises as the silicon layer 1 of basalis, the graphene layer 3 that is formed at the silicon dioxide layer 2 on silicon layer and is formed on silicon dioxide layer.Described graphene layer 3 can be formed at the local of silicon dioxide layer in the mode covering silicon dioxide layer local, also can be formed on silicon dioxide layer in the mode covering whole silicon dioxide layer.In addition, in order to characterize doping effect by direct current transportation method, can also arrange electrode at described graphene layer two ends and construct graphene field effect transistor device, wherein electrode 5 is respectively source electrode and drain electrode, and silicon layer 1 is grid.
Main purpose of the present invention is to adulterate to the graphene layer in graphene device, and to the preparation method of the thickness of the substrate silicon layer 1 in described graphene device, the thickness of silicon dioxide layer 2, the thickness of graphene layer 3 and graphene device, there is no particular limitation, the thickness of the thickness of silicon layer of the described end 1, the thickness of silicon dioxide layer 2, graphene layer 3 can be various thickness known in the field, and the preparation method of described graphene device can adopt known method.
Such as, in the present invention, the thickness of described silicon layer 1 can be 0.3-2mm, and the thickness of described silicon dioxide layer 2 can be 100-300nm, and the thickness of described graphene layer 3 can be 0.34-2nm.
As the preparation method of graphene device, can by micromechanics stripping method described later, the silicon chip on surface with silicon dioxide layer forms graphene layer.Can by commercially available as the described silicon chip on surface with silicon dioxide layer, such as can use the silicon chip being available commercially from SVM company of the U.S., this silicon wafer thickness is 0.5 millimeter (for including the gross thickness of the silicon chip of the silicon dioxide layer of silicon layer and silicon surface) and has the thick silicon dioxide layer of 285nm.
According to the present invention, by being formed with polymethyl methacrylate film 4 of the present invention on graphene layer 3, the effect storing electrostatic charge can be had.
Preferably, the thickness of described polymethyl methacrylate film is 20-50nm, and more preferably the thickness of polymethyl methacrylate film is 30-45nm, more preferably 35-45nm.
According to the present invention, the method that the surperficial graphene layer of graphene device is formed polymethyl methacrylate film has no particular limits, as long as can form the polymethyl methacrylate film of above-mentioned thickness range on the graphene layer of described graphene device.Such as, can be undertaken by spin-coating method known in the field.Described spin-coating method is: by by polymethyl methacrylate, (number-average molecular weight is 25000-1000000, is preferably 950000; Number-average molecular weight adopts Japanese Shimadzu Corporation to produce LC-20A type liquid phase gel permeation chromatograph and measures, and adopts single aperture chromatographic column
with
four post couplings.Mobile phase is oxolane, and flow velocity is 0.7mL/min; Sample solution concentration is 2mg/mL, and sample size is 200 μ L; Probe temperature is 35 DEG C; Using single distribution polystyrene as standard sample.) solution coat on graphene device, then obtaining polymethyl methacrylate film by drying.Solvent in described polymethyl methacrylate solution for have good dissolubility to polymethyl methacrylate, and can be easy to the solvent of volatilization.Such as can enumerate as such solvent: chlorobenzene and/or methyl phenyl ethers anisole.
In addition, for the content of polymethyl methacrylate in polymethyl methacrylate solution, also there is no particular limitation, can be the customary amount of this area for being coated with.Under preferable case, in described polymethyl methacrylate solution, the content of polymethyl methacrylate is 2-10 % by weight, is more preferably 3-5 % by weight.
In addition, the condition of spin coating with the thickness obtaining dried polymethyl methacrylate film for 20-50nm is as the criterion.The speed of such as described spin coating can be 3000-5000rpm/min, and the time of spin coating is 0.5-5 minute; The speed of preferred spin coating is 3400-4500rpm/min, and the time of spin coating is 1-2 minute.
Can be condition well known in the art for condition dry after spin coating, such as can at 100-160 DEG C dry 5-30 minute; Preferably dry 8-20 minute at 120-150 DEG C.
According to the present invention, because the polymethyl methacrylate film obtained by above-mentioned spin-coating method is transparence film, after therefore can being amplified graphene device surface by light microscope, Primary Location is carried out to Graphene region.In the present invention, described " Primary Location " refers to and to position the region with graphene layer on graphene device.
As long as the light microscope that can realize amplification more than 100 times (being preferably 100-1000 doubly) in principle all can carry out Primary Location to the Graphene region on graphene device.But consider from the continuity of operation, preferably use the atomic force microscope in subsequent step to carry out Primary Location to the Graphene region on graphene device.When carrying out Primary Location by atomic force microscope to the Graphene region on graphene device, only need the amplification mode using atomic force microscope.
According to the present invention, after Primary Location being carried out to Graphene region under the amplification mode of atomic force microscope, can in the electrostatic force microscope pattern of atomic force microscope, accurately locate (namely to the Graphene region of needs doping under friction force microscope pattern or Kelvin force microscopy pattern, first the optical amplifier module utilizing atomic force microscope to carry finds Graphene, then electrostatic force microscope pattern is utilized, any one pattern in friction force microscope pattern or Kelvin force microscopy pattern carries out scanning imagery, by the image of the features such as the thickness of graphene device or shape with scanning gained is compared, determine the exact position of Graphene).At this, described " accurately locating " refers to that, to needing the region of adulterating to position in Graphene region, the region of these needs doping can be the part in the Graphene region of above-mentioned Primary Location, also can be the whole of the Graphene region of above-mentioned Primary Location.Because the present invention can partly or entirely adulterating to the Graphene region of Primary Location, therefore can realize Graphene doping in situ, and the size of doped region and position controlled, the shape of doped region can variation.
According to the present invention, after the Graphene region of needs doping is accurately located, import electric charge by the conductive pin of atomic force microscope to described Graphene region again to adulterate, described method of carrying out adulterating is: under the contact mode of atomic force microscope, by conductive pinpoint, described Graphene region is scanned, thus adulterate.
According to the present invention, the condition of carrying out adulterating to described Graphene region importing electric charge by the conductive pin of atomic force microscope comprises: the voltage difference between conductive pinpoint and the basalis of graphene device is 3-18V, force value between conductive pinpoint and graphene layer is 0.2-0.7V, and the sweep speed of conductive pinpoint is 0.1-0.5Hz.Under preferable case, the voltage difference between conductive pinpoint and the basalis of graphene device is 5-13V, and the force value between conductive pinpoint and graphene layer is 0.4-0.6V, and the sweep speed of conductive pinpoint is 0.1-0.3Hz.
In the present invention, described " force value between conductive pinpoint and graphene layer " refers to the side-play amount due to the stressed bending LASER SPECKLE caused of tip, this side-play amount is recorded by 4 quadrant detector, particularly, the detection of the power in atomic force microscope between needle point and graphene layer is realized by detection needle point cantilever bending degree, beam of laser is beaten on tip, when there is pressure between needle point and sample, tip can bend thus cause the LASER SPECKLE position reflected back instead to be given birth to and change, the pressure between needle point and sample can be obtained by the amount of movement of the position of 4 quadrant detector recording laser spot, this force value represents with unit V in atomic force microscope.
According to the present invention, the number of times of described scanning can decide according to the concentration that need adulterate, and under normal circumstances, can be 1-4 time, is preferably 2-3 time.
According to the present invention, in preferred situation, described conductive pin can be the conductive pin with coat of metal ordinary silicon or highly doped silicon known in the field, on silicon needle point, be preferably coated with the conductive pin of metal level.The metal of described metal level can be generally used for for this area the metal that conducts electricity, is preferably platinumiridio.
According to the present invention, the way of contact in described conductive pin and Graphene region can be Intermittent Contact (contact frequency can be 0.1-2Hz, the force value between conductive pinpoint and graphene layer can 0.1-0.5V), also can be continuous contact.Consider from doping effect, preferably in doping process, described conductive pin contacts with Graphene regional sustained.
According to the present invention, use the graphene device after not executing the doping of alive conductive pinpoint Multiple-Scan, doping can be moved back to the Graphene after doping, thus return to its original non-dopant states.
In the present invention, move back doping process and doping process difference and be only that voltage between conductive pinpoint and graphene device basalis is contrary or be zero with voltage during doping, other conditions are identical with the condition of above-mentioned doping.
The present invention also provides a kind of doped graphene, and wherein, this doped graphene is prepared by above-mentioned method.
Below will be described the present invention by embodiment, but the present invention is not limited in following embodiment.
In following examples, the number-average molecular weight of polymethyl methacrylate adopts Japanese Shimadzu Corporation to produce LC-20A type liquid phase gel permeation chromatograph and measures, adopt single aperture chromatographic column
with
four post couplings.Mobile phase is oxolane, and flow velocity is 0.7mL/min; Sample solution concentration is 2mg/mL, and sample size is 200 μ L; Probe temperature is 35 DEG C; Using single distribution polystyrene as standard sample.
In following examples, the surface potential of graphene layer by recording under Kelvin force microscopy pattern, its concrete grammar is: be fixed on by sample on the sample stage of atomic force microscope, under making atomic force microscope be operated in Kelvin Force scan pattern, utilize conductive pinpoint scanning samples surface, the surface potential figure of scanning area can be obtained.
The polarity of doping electric charge is transported by the direct current of device and records, its concrete grammar is: by changing the grid voltage putting on silicon chip lower surface, voltage constant between graphene layer two ends source electrode and drain electrode (electrode 5 namely in Fig. 1), then the electric current by graphene layer is measured, finally obtain by the electric current of the graphene layer variation relation with grid voltage, i.e. the transfer characteristic curve of device.At this, if the transfer curve of device is moved to the left relative to before doping after doping, be then negative electrical charge doping, otherwise, be then positive charge doping.
Doping content is by formula Δ n=α Δ V
diraccalculate, wherein, Δ n is doping content, and α is relevant to the geometric capacitance of substrate, α=7.2 × 10
10cm
-2(calculated by the thickness of oxide layer and dielectric constant thereof and obtain), Δ V
driacfor device doping before and after transfer curve amount of movement (circular be for the overall situation doping (embodiment 3), and doping after do not formed pn tie, Δ V
driacthe grid voltage at the minimum place of transfer curve electric current of device before doping is deducted for the grid voltage at the minimum place of transfer curve electric current of device after adulterating; For local doping (embodiment 2), Δ V
driacthe grid voltage corresponding for two minimum places of electric current of the transfer curve of device after adulterating is poor, and being 27V in fig. 2, is 11V in figure 3).
In following examples, the method adopting micromechanics stripping method to form graphene layer on following silicon chip is: be sprinkling upon on adhesive tape by clastic graphite, then adhesive tape is repeatedly pasted, thicker graphite scrap is peeled off into the graphite of thinner (about 0.3nm), then this adhesive tape is affixed on described silicon chip, after finally taking away adhesive tape, understands the graphene layer leaving random distribution at the bottom of described silicon wafer-based.
The silicon chip used in following examples and comparative example is purchased from SVM company of the U.S., and silicon wafer thickness is 0.5 millimeter (referring to the gross thickness of the silicon chip of the silicon dioxide layer including silicon layer and silicon surface) and has the thick silicon dioxide layer of 285nm.
The microscope used in following examples and comparative example is atomic force microscope, and its manufacturer is Bruker company of the U.S., and model is Dimension Icon.This atomic force microscope also has electrostatic force microscope pattern, friction force microscope pattern and Kelvin force microscopy pattern.And this instrument integration has optical amplifier function.
In following examples, direct current transport measure use for Keithley(Keithley) company's model of producing is the semiconductor property tester of 4200-SCS.
The conductive pin used in following examples and the comparative example model of producing for Bruker company for SCM-PIT(be the conductive pin being coated with platinumiridio layer on silicon tip).
Embodiment 1
By micromechanics stripping method at the upper obtained graphene layer of the silicon chip (oxide layer that surface has 285nm thick) of 0.5 millimeters thick, obtain graphene device.By concentration be 4 % by weight polymethyl methacrylate (number-average molecular weight is 950000, identical below) solution (solvent is chlorobenzene) be spin-coated on graphene device have on the surface of graphene layer, spin speed is 4000rpm, spin-coating time is 1.5 minutes, then at 150 DEG C dry 10 minutes, the film that thickness is 38nm is obtained.On graphene device, the region with graphene layer is found by atomic force microscope (amplification mode: 1000 times), and by accurately locating the Graphene region that need adulterate under the electrostatic force microscope pattern of atomic force microscope.Then under the contact mode of atomic force microscope, 7V voltage is applied to conductive pinpoint, by graphene device ground connection, to selected whole Graphene region continuous sweep twice (conductive pinpoint contacts with Graphene regional sustained), in scanning process, the pressure controlled between needle point and graphene layer is 0.5V, and sweep speed is 0.1Hz.
By measuring the surface potential of graphene layer under the Kelvin force microscopy pattern of atomic force microscope, the transfer characteristic curve measuring graphene device is transported by the direct current of graphene device, again by amount of movement (wherein, the Δ V of transfer characteristic curve before and after graphene device doping
driacdeducting the grid voltage at the minimum place of transfer curve electric current of device before doping for the grid voltage at the minimum place of transfer curve electric current of device after adulterating, is 23V) and the computing formula of above-mentioned doping content obtain doping content.According to above-mentioned method of measurement, the Graphene region surface electromotive force after doping increases 1.37V, and the result that direct current transports is indicated as negative electrical charge doping, and doping content is 1.66 × 10
12cm
-2.
Doping treatment is moved back to the above-mentioned graphene device adulterated, detailed process is: under making atomic force microscope be operated in contact mode,-1V voltage is applied to conductive pinpoint, by graphene device ground connection, to doped graphene region continuous sweep four times (conductive pinpoint contacts with Graphene regional sustained), the pressure controlled between needle point and graphene layer is 0.5V, and sweep speed is 0.1Hz.After moving back doping, the surface potential added value of original doped region is reduced to 0.06V by 1.37V.
Embodiment 2
By micromechanics stripping method at the upper obtained graphene layer of the silicon chip (oxide layer that surface has 285nm thick) of 0.5 millimeters thick, obtain graphene device.By concentration be 4 % by weight polymethyl methacrylate solution (solvent is methyl phenyl ethers anisole) be spin-coated on graphene device have on the surface of graphene layer, spin speed is 4000rpm, spin-coating time is 2 minutes, then at 150 DEG C dry 10 minutes, obtains the film that thickness is 36nm.On graphene device, the region with graphene layer is found by atomic force microscope (amplification mode: 1000 times), and by accurately locating the Graphene region that need adulterate under the electrostatic force microscope pattern of atomic force microscope.Then under the contact mode of atomic force microscope, 10V voltage is applied to conductive pinpoint,-3V voltage is applied to the silicon layer of graphene device, the Graphene region continuous sweep twice (conductive pinpoint contacts with Graphene regional sustained) of the need doping in location, doped region accounts for the half of whole Graphene region area, in scanning process, the pressure controlled between needle point and graphene layer is 0.4V, and sweep speed is 0.2Hz.
By measuring the surface potential of graphene layer under the Kelvin force microscopy pattern of atomic force microscope, transported the transfer characteristic curve measuring graphene device by the direct current of graphene device, then obtain doping content by the amount of movement (see Fig. 2) of transfer characteristic curve and the computing formula of above-mentioned doping content before and after device doping.According to above-mentioned method of measurement, Graphene doped region increases 2.55V relative to non-doped region surface potential, the result that direct current transports shows successfully to achieve local doping to sample, form Graphene pn knot, doping electric charge is negative, and doped region increases by 1.99 × 10 relative to non-doped region positive charge concentration
12cm
-2.Concrete wherein, (a) in Fig. 2 is the graphenic surface potential energy diagram after local doping as shown in Figure 2, and in figure, the region of the interior mark of dashed rectangle is Graphene region, and middle brighter areas is positive charge injection zone, and both sides comparatively dark areas are non-iunjected charge region; (b) in Fig. 2 is the transfer characteristic curve of the graphene device before and after doping, and wherein, being solid line before doping, is dotted line after doping, and the appearance of second dirac point shows that Graphene success is adulterated by local, forms pn knot.
Embodiment 3
By micromechanics stripping method at the upper obtained graphene layer of the silicon chip (oxide layer that surface has 285nm thick) of 0.5 millimeters thick, obtain graphene device.By concentration be 4 % by weight polymethyl methacrylate solution (solvent is chlorobenzene) be spin-coated on graphene device have on the surface of graphene layer, spin speed is 4000rpm, spin-coating time is 1 minute, then at 150 DEG C dry 10 minutes, obtains the film that thickness is 40nm.On graphene device, the region with graphene layer is found by atomic force microscope (amplification mode: 1000 times), and by accurately locating the Graphene region that need adulterate under the electrostatic force microscope pattern of atomic force microscope.Then under the contact mode of atomic force microscope,-8V voltage is applied to conductive pinpoint, by graphene device ground connection, in selected whole Graphene region continuous sweep twice (conductive pinpoint contacts with Graphene regional sustained), in scanning process, the pressure controlled between needle point and graphene layer is 0.6V, and sweep speed is 0.3Hz.
By measuring the surface potential of graphene layer under the Kelvin force microscopy pattern of atomic force microscope, the transfer characteristic curve measuring graphene device is transported by the direct current of graphene device, before and after being adulterated by device, the amount of movement of transfer curve is (see Fig. 3 again, wherein, be solid line before doping, doping is afterwards dotted line) and the computing formula of above-mentioned doping content obtain doping content.According to above-mentioned method of measurement, the graphene layer surface potential after doping reduces 0.66V, and the result that direct current transports shows successfully to achieve overall situation doping to Graphene region, and doping electric charge is just, doping content is 7.92 × 10
11cm
-2.
Embodiment 4
Carry out according to the method for embodiment 3, adopt the mode got ready and Graphene region to carry out Intermittent Contact unlike, the mode that conductive pinpoint and Graphene region carry out contacting.
Known by the surface potential measuring graphene layer under the Kelvin force microscopy pattern of atomic force microscope, the Graphene region surface electromotive force after doping increases 26mV.
Comparative example 1
Carry out according to the method for embodiment 1, unlike, on graphene device, do not form polymethyl methacrylate film.Direct current transports measurement result and finds that its transfer curve of sample after adopting the method doping does not move, and illustrates that the method can not form Effective Doping to Graphene.
According to above-described embodiment, the method for being adulterated by Graphene provided by the invention can realize Graphene doping in situ, the various shapes of doped region, and the controlled and continuously adjustabe of doping content, can move back doping to the sample adulterated in addition.
More than describe the preferred embodiment of the present invention in detail; but the present invention is not limited to the detail in above-mentioned execution mode, within the scope of technical conceive of the present invention; can carry out multiple simple variant to technical scheme of the present invention, these simple variant all belong to protection scope of the present invention.It should be noted that in addition, each concrete technical characteristic described in above-mentioned embodiment, in reconcilable situation, can be combined by any suitable mode, in order to avoid unnecessary repetition, the present invention illustrates no longer separately to various possible compound mode.
In addition, also can carry out combination in any between various different execution mode of the present invention, as long as it is without prejudice to thought of the present invention, it should be considered as content disclosed in this invention equally.
Claims (10)
1. a method for Graphene doping, it is characterized in that, the method comprises the following steps:
1) on the surperficial graphene layer of graphene device, polymethyl methacrylate film is formed;
2) the Graphene region needing doping is selected;
3) import electric charge by the conductive pinpoint of atomic force microscope to selected Graphene region to adulterate.
2. method according to claim 1, wherein, described graphene device comprises: as the silicon layer of basalis, is formed at the silicon dioxide layer on silicon layer, is formed at the graphene layer on silicon dioxide layer.
3. method according to claim 1, wherein, the thickness of described polymethyl methacrylate film is 20-50nm.
4. method according to claim 3, wherein, the thickness of described polymethyl methacrylate film is 35-40nm.
5. method according to claim 1, wherein, select to need the method in Graphene region of doping be: after carrying out Primary Location by the amplification mode of atomic force microscope to Graphene region, then by under the electrostatic force microscope pattern of atomic force microscope, friction force microscope pattern or Kelvin force microscopy pattern to needing the Graphene region of adulterating accurately to locate.
6. according to the method in claim 1-5 described in any one, wherein, the method of carrying out adulterating to described Graphene region importing electric charge by the conductive pin of atomic force microscope is: under the contact mode of atomic force microscope, by conductive pinpoint, selected Graphene region is scanned, thus adulterate.
7. method according to claim 6, wherein, the condition of carrying out adulterating to described Graphene region importing electric charge by the conductive pin of atomic force microscope comprises: the voltage difference between conductive pinpoint and the basalis of graphene device is 3-18V, force value between conductive pinpoint and graphene layer is 0.2-0.7V, and the sweep speed of conductive pinpoint is 0.1-0.5Hz.
8. method according to claim 7, wherein, the condition of carrying out adulterating to described Graphene region importing electric charge by the conductive pin of atomic force microscope comprises: the voltage difference between conductive pinpoint and the basalis of graphene device is 5-13V, force value between conductive pinpoint and graphene layer is 0.4-0.6V, and the sweep speed of conductive pinpoint is 0.1-0.3Hz.
9. method according to claim 1, wherein, described conductive pin is the conductive pin being coated with metal level on silicon needle surface.
10. a doped graphene, is characterized in that, this doped graphene is prepared by the method in claim 1-9 described in any one.
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| CN110117780A (en) * | 2019-03-19 | 2019-08-13 | 中国科学院上海微系统与信息技术研究所 | A kind of two-dimensional material layer and preparation method |
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