CN111620298A

CN111620298A - Method for cutting metal nano structure, assembling nano device and characterizing nano device in situ

Info

Publication number: CN111620298A
Application number: CN202010465765.8A
Authority: CN
Inventors: 刘泽
Original assignee: Wuhan University WHU
Current assignee: Wuhan University WHU
Priority date: 2020-05-28
Filing date: 2020-05-28
Publication date: 2020-09-04
Anticipated expiration: 2040-05-28
Also published as: CN111620298B

Abstract

The invention discloses a method for cutting a metal nano structure, assembling a nano device and characterizing the nano device in situ. The method for cutting and assembling the nanometer device is completed in situ under a scanning electron microscope and comprises the following steps: (1) connecting the conductive probe with the metal nano structure through a short circuit of a lead, and controlling the conductive probe to be close to and contact with the metal nano structure; (2) moving the conductive probe away from the metal nanostructure while breaking the short circuit connection; (3) moving the conductive probe to be close to the metal nanostructure, so that the metal nanostructure is locally melted and partially transferred, attached to the tip of the conductive probe, forming a nano device having the metal nanostructure attached to the tip, and forming a nano ball at the tip of the metal nanostructure. Methods of in situ characterization are also provided to obtain microstructure-electrical property relationships. The method provided by the invention has great reference value and application potential.

Description

Method for cutting metal nano structure, assembling nano device and characterizing nano device in situ

Technical Field

The invention belongs to the field of nano manufacturing, and particularly relates to a cutting method of a metal and metal alloy nano structure and a method for assembling and characterizing a nano device.

Background

The performance of the metal nano structure in the aspects of light, electricity, magnetism, catalysis and the like can be obviously improved by modulating the shape of the metal nano structure, so that the metal nano structure has wide application in the aspects of batteries, catalysis, optics, sensing, surface physical chemistry and the like. Conventional methods for modulating the shape of metal nanostructures and fabricating metal nanostructure-based devices typically employ advanced photolithography techniques. Since photolithography is based on planar micromachining processes, there are also significant challenges in fabricating more complex three-dimensional nanostructures or nanodevices. Although focused ion beam technology can locally engrave nanostructures, it is based on the bombardment of the nanostructures by energetic particles, which can cause the high-energy particles to embed into the surface of the fabricated nanostructure or device, causing contamination. On The other hand, electrical characterization of nanodevices to study The microstructure and electrical properties usually requires additional processing of electrodes and a four-probe test method to reduce The effect of contact resistance, see in detail The article entitled "The 100th and The laboratory of The four-point probe technique" published in Journal of Physics, Journal of coherent Matter, volume 27, pages 1-29, 5.18.5.2015. In particular, characterization of Electrical properties of molten metals relies on complex equipment, as detailed in paper entitled "Electrical resistance MEASUREMENT of liquid metals" published in the journal of MEASUREMENT SCIENCE AND TECHNOLOGY, Vol.16, page number 417-.

At present, there are a few documents reporting methods for in-situ assembly of nanodevices. Such as: welding of nanostructures is achieved by joule heating of a Solder in a Nano volume by an input current, which is described in detail in paper published on Nano Letters journal at volume 9, page number 91-96, entitled "Bottom-up nanostructuring by the Welding of Metallic Nanoobjects Using Nanoscale sol", 12.10.2009; welding Pt nanowires to the conductive probe tips by Joule heating with an input current, in detail refer to the paper entitled "Welding of Pt nanowires by Joule" published in ScriptA materials journal, volume 57, page number 953-956, on 14 th month, 2007; the preparation of nano-heterojunctions is achieved by chemical growth, or by electron beam induced carbon deposition welding, or by applying high electric, optical or thermal fields, with particular reference to The paper entitled "The creation of nanojunctions", published on Nanoscale journal, volume 2, page 2521-2529, 9.2010. Although some nanostructures with complex configurations can be prepared by the method, the method usually depends on external applied voltage/current or high-energy particle irradiation, and is not easy to control and easily causes pollution to the prepared device.

The existing methods for modulating the shape of a metal nano structure and preparing a device based on the metal nano structure have the problems of over-high equipment threshold, high process control difficulty, easy pollution and the like.

Disclosure of Invention

In order to solve the above technical problems, the present invention provides a novel, convenient, high-precision and controllable nano-fabrication technology by providing methods of cutting metal nanostructures, assembling nano-devices, and performing in-situ characterization on the assembled nano-devices in various embodiments.

Different from the traditional method for assembling the nano device by welding input current or voltage, the invention applies quantum tunneling effect and can realize the tailoring of the shape of the metal nano structure under the irradiation of incident electrons with lower energy (as little as 1 kilo-electron volt) even without external input voltage or current. The principle is based on the following experimental findings: when the distance between the two metal nano structures is as small as within 1 nanometer, the potential difference generated by electron irradiation can induce electron field emission, so that the metal nano structures are locally melted and material transfer and welding occur. Based on the experiment, the invention provides a method for cutting the metal nano structure in situ and assembling the metal nano structure into the nano device, and also provides a 2-probe method for representing the electrical property of the nano device, which is simple, convenient and free from the influence of contact resistance.

The technical scheme provided by the invention is as follows:

one of the objectives of the present invention is to provide a method for cutting and assembling metal nanostructures into nano devices, which is completed in situ under a scanning electron microscope, and comprises the following steps:

(1) connecting the conductive probe with the metal nano structure through a short circuit of a lead, and controlling the conductive probe to be close to and contact with the metal nano structure;

(2) moving the conductive probe away from the metal nanostructure while breaking the short circuit connection;

(3) moving the conductive probe to be close to the metal nanostructure, so that the metal nanostructure is locally melted and partially transferred, attached to the tip of the conductive probe, forming a nano device having the metal nanostructure attached to the tip, and forming a nano ball at the tip of the metal nanostructure.

Further, the accelerating voltage of the scanning electron microscope is more than or equal to 1 kilo-electron volt.

Further, the material of the conductive probe comprises W, Ag and Au.

Further, the shape of the metal nanostructure In step (1) includes a rod-like, column-like, cone-like or wire-like configuration, and the material includes metals of Au, Cu, Pt, Ag, In, Sn, Bi, Pb, Zn, Al, Pd, Ti, Ni, Co, Fe or alloys thereof.

Further, the nano device includes a nano tip probe, a nano sphere probe, a nano column probe, a heterojunction, and a combination thereof.

Further, the conductive probe is moved in the step (3) to be close to the metal nano structure within the range of 0.1nm-1000 nm.

Further, the conductive probe is moved by the driving device, and the shape of the nanometer device is modulated by controlling the moving speed of the driving device in the step (2), wherein the faster the moving speed of the conductive probe is, the sharper the shape of the nanometer device obtained at the tip of the conductive probe and the tip of the metal nanometer structure is. Preferably, the driving means is a nanotechnology robot.

Further, the method for cutting and assembling the metal nanostructure into the nano device can be repeatedly performed, that is, the manufactured nano device is used as a new conductive probe, and the method steps for cutting and assembling the metal nanostructure into the nano device according to claim 1 are repeated to form the nano device with the metal nanostructure attached to the tip of the nano device again.

Further, the range of the potential difference U applied between the conductive probe and the metal nano structure after the conductive probe is contacted with the metal nano structure or in the approaching process is more than or equal to 0 and less than or equal to 100 volts.

The method for cutting and assembling the metal nano structure into the nano device is shown as the following figure 1 (a):

1) fixing a metal substrate 5 with a metal nano structure 4 on the surface on a sample stage of a scanning electron microscope 1, fixing a conductive probe 3 on a driving device arranged in a cavity of the scanning electron microscope, then connecting the conductive probe 3 and the metal substrate in a short circuit mode (closing switches 6 and 7), and driving the conductive probe to be close to and contact with the metal nano structure 4 in an in-situ mode under the state that a scanning electron beam 2 is opened;

2) moving the conductive probe 3 a distance away from the metal nanostructure 4 and then opening the switch 7 (switch 6 can also be opened);

3) moving the conductive probe 3 close to the metal nanostructure 4 such that the metal nanostructure 4 is locally melted and partially transferred, attached to the tip of the conductive probe 3, forming a nanodevice 9 having a tip attached to the metal nanostructure and a metal nanostructure forming a nanosphere at the tip of the metal nanostructure 4.

Another object of the present invention is to provide a method for in-situ characterization of the above-mentioned nano-device, comprising the following steps:

(1) connecting the prepared nano device with a metal electrode through a short circuit of a lead, and moving the nano device to be close to and contact with the metal electrode;

(2) breaking said short circuit connection and applying a potential difference between said nanodevice and said metal electrode;

(3) and moving the nanometer device under the condition that the nanometer device is kept in contact with the metal electrode, so that the contact state between the nanometer device and the metal electrode is changed, and simultaneously monitoring a voltage-current curve to obtain the microstructure-electrical property relation of the nanometer device.

The method of in situ characterization is shown in FIG. 1 (b):

1) short-circuiting the prepared nanodevices 9 to the metal substrate 5 (closing the switch 7), moving the nanodevices 9 close to and in contact with the metal substrate 5;

2) applying a potential difference between the nano device 9 and the metal substrate 5 (opening the switch 7), and locally melting the contact area of the nano device 9 and the metal substrate 5 by joule heating to form a liquid bridge;

3) the nano device 9 is driven to move, so that the size (contact state) of a liquid bridge between the nano device 9 and the metal substrate 5 is changed, and a voltage-current curve is monitored to obtain the microstructure-electrical property relation of the metal nano structure at the tip of the nano device 9.

If the switch 7 is closed after step 2), the formed liquid bridge will solidify, at which point if the nanodevices 9 are driven away from the metal substrate 5, the solidified liquid bridge will neck down until opened, thereby forming sharp nanopipettes on the surfaces of the nanodevices 9 and the metal substrate 5.

The invention principle is as follows:

the principle of cutting metal nano structure and assembling nano device is as follows: scanning electrons in a scanning electron microscope can form weak potential difference on the surfaces of two mutually close metal electrodes which are disconnected, when the distance between the two electrodes is as small as within 1 nanometer, the quantum tunneling effect causes field emission electrons, and the position of the metal nanostructure for local melting is determined by the energy carried by the field emission electrons compared with the height of the Fermi level and the Joule heating effect caused by the field emission current. In general, the emission current density (J, unit: A/cm) of the surface field of the metal electrode²) Given by Fowler-Nordheim theory

Wherein E (unit: V/cm) is the electric field intensity of the surface of the metal electrode,

(unit: eV) is the work function of the metal electrode. t is t²(y)≈1.1，v(y)≈0.95-y²，

Typically for the metal of Pt it is preferred that,

we driven the tungsten probe close to a Pt nanopillar (fig. 2(a)) and gradually increased the input voltage, we measured that the field emission voltage was about 2.3 volts and the field emission current density was about 1.1 × 10⁴A/cm²(FIG. 2 (b)). This means that the current density required to melt the Pt nano-pillars in fig. 2(a) is 10⁴A/cm²Magnitude. However, we found experimentally that even with an external input voltage as small as 1mV, melting of the Pt nanopillar tip occurred during driving of the tungsten probe close to a Pt nanopillar having a similar size to that of fig. 2(a), 10 according to equation (1), and⁴A/cm²the current density of (2) requires that the electric field intensity between the metal electrodes be 10⁷Of the order of V/cm, which means the metal electrode spacing

This value is smaller than the lattice constant! Therefore, the field emission current found by our experiments is not originated from Fowler-Nordheim mechanism. We note that quantum tunneling effects can lead to the transfer of charge (Q, unit: C) when the metal electrode spacing is as small as within 1 nanometer

Q＝σ(d)·E·S·t (2)

Wherein E, S, t represents the electric field strength between the metal electrodes, the area of the metal electrodes facing each other, and the time, respectively. σ (d) is the conductivity of the tunnel junction formed by the metal electrodes, which is apparently a function of the electrode spacing d. At low voltages and assuming planar electrodes, there are

Wherein

Is the wavelength of the tunneling electron, m is the mass of the electron,

h is the Planck constant. Substituting equation (3) into equation (2), we have

Substituting a typical electrode spacing d-0.3 nm for quantum tunneling, an applied voltage of 1mV, and a work function of Pt, a current density of J3.0 × 10⁴A/cm²This corresponds to the experimentally measured current density value required to locally melt the Pt nanopillars (fig. 2).

The principle of the 2-probe method for characterizing the electrical properties of the prepared nanometer device without the influence of contact resistance provided by the invention is as follows: when a liquid bridge is formed between the nanometer device and the metal substrate, the resistance in the circuit is as follows:

R＝R₀+R_n(5)

wherein a constant resistance R₀Indicating the resistance of the circuit outside the liquid bridge region, R_nRepresenting the resistance of the liquid bridge, the value of which depends on the size L of the liquid bridge

Where ρ is_mIs the resistance of the liquid bridge. When the nano-device is driven to move so that the size of the liquid bridge changes, the loop resistance outside the liquid bridge area can be regarded as constant, so that the measured change of the circuit resistance only comes from the change of the liquid bridge resistance. By continuously changing the size of the liquid bridge, experimental data of the circuit resistance and the size of the liquid bridge can be obtained, and the resistivity of the liquid bridge can be conveniently measured by combining a theoretical formula (6).

The invention has the beneficial effects that:

the invention applies quantum tunneling effect, and can realize the cutting and assembly of the shape of the metal nano structure under the irradiation of incident electrons with lower energy (as little as 1 kilo-electron volt) even without external input voltage or current. The method has the advantages of low requirement on equipment threshold, simple process, convenient operation and no pollution in the preparation process.

The invention also provides a method for controlling the shape of the metal nanostructure by controlling the moving speed of the probe. The faster the moving speed of the conductive probe is, the sharper the shape of the nano device obtained at the tip of the conductive probe and the tip of the metal nano structure is, which facilitates the customization of different shapes.

The invention also provides a simple and convenient 2-probe method for characterizing the electrical property of the nanometer device without the influence of contact resistance.

The invention develops a new idea for cutting and assembling the shape of the metal nano structure and representing the electrical property, and has great reference value and application potential.

Drawings

Exemplary embodiments of the invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 provides a schematic illustration of a technical solution; in the figure, 1 is a scanning electron microscope, 2 is a scanning electron beam, 3 is a conductive probe, 4 is a metal nanostructure, 5 is a metal substrate, 6 and 7 are switches, and 8 is a source table; FIG. 1(a) is a schematic diagram of in-situ tailoring of metal nanostructures, i.e., assembly of nanodevices, and FIG. 1(b) is a schematic diagram of in-situ characterization of electrical properties of metal nanostructures;

fig. 2 illustrates the measurement of the field emission effect during the approach of a tungsten tip to a Pt nanopillar under the conditions of an external source table. FIG. 2(a) shows the change of the morphology of Pt nano-pillars before and after field emission during the approaching process of the tungsten tip; FIG. 2(b) field emission voltage-current curves recorded by the source table;

FIG. 3 is a schematic diagram showing a W tip-Au nanosphere device prepared by electron beam irradiation induced field emission during the process of the W tip approaching the Au nanocolumn, with the W tip and the Au nanocolumn both in an open circuit state with the outside;

fig. 4 exemplarily shows the transmission electron microscopy characterization results of one fabricated tungsten tip-Pt nanosphere device. FIG. 4(a) is the prepared tungsten tip-Pt nanosphere device transferred to a Mo net; FIG. 4(b) is a morphology diagram of a tungsten tip-Pt nanosphere device; FIGS. 4(c) - (d) are views of eds mapping; FIG. 4(e) is a graph of the content of ingredients at positions (i) and (ii); FIG. 4(f) is a high-resolution transmission electron microscope image of the welding interface of the tungsten needle tip-Pt nanosphere;

fig. 5(a) exemplarily shows a tungsten tip-Pt nanopillar-Pt nanoball device prepared by locally melting electron beam-induced field emission at the middle portion of a Pt nanopillar while a tungsten tip approaches a longer Pt nanopillar; FIG. 5(b) schematically shows a complex-shaped nanodevice prepared by repeating the process of FIG. 5 (a);

fig. 6 exemplarily shows a tungsten probe-Pt nanopillar-Ag nanopillar heterojunction prepared after a tungsten tip is respectively brought close to a Pt nanopillar and an Ag nanopillar; FIGS. 6(a) - (b) are topographical maps; FIGS. 6(c) - (e) are electron diffraction patterns of selected regions near the Pt-Ag heterojunction;

fig. 7 exemplarily shows tungsten tip-Pt nanosphere beads (fig. 7(a)) prepared by tungsten tip repeated proximity to Pt nanopillar array and Pt nanopillar array with nanosphere tip (fig. 7 (b));

FIG. 8 shows exemplary scanning electron micrographs of Ag (FIG. 8(a)) and CuZnSn (FIG. 8(b)) and PtCuNiP (FIG. 8(c)) alloy nanopillars with shape tailoring;

fig. 9(a) exemplarily shows a process of necking by moving a tungsten tip after welding the tungsten tip and an Ag nanopillar; fig. 9(b) exemplarily shows a sharp tungsten tip and an Ag nanopillar tip fabricated by necking until breaking through the process of fig. 9 (a);

FIG. 10 is a scanning electron micrograph showing exemplary nanostructures of different degrees of sharpness obtained at the tip of a tungsten probe and the tip of a Pt nanostructure by controlling the speed of travel of the tungsten probe; fig. 10(a) and 10(c) are respectively a picture before moving the tungsten probe, and fig. 10(b) and 10(d) are respectively a picture after the tungsten probe moves at different speeds and is separated from the Pt nanostructure in fig. 10(a) and 10 (c);

FIG. 11 shows exemplary scanning electron micrographs before and after formation of a Pt liquid bridge after one tungsten tip-Pt nanosphere device contacts a Pt nanostructure;

FIG. 12 shows an exemplary voltage-current curve measured by moving one tungsten probe so that the size of a Pt liquid bridge formed between the tungsten probe and a Pt substrate is changed (FIG. 12 (a)); the data points in FIG. 12(b) are the measured resistance versus the size of the Pt liquid bridge, and the solid line is the theoretical curve obtained based on equation (1).

Detailed Description

The presently preferred embodiments and methods of the present invention, which constitute the presently preferred modes of carrying out the invention by the inventors, are described in greater detail below with reference to the accompanying drawings. However, the embodiments disclosed herein are merely exemplary of the invention and therefore the details of the disclosed implementations are merely representative bases for the invention and should not be construed as limiting the invention. The invention may encompass different implementation-specific schemes and methods. In the following examples, metal nanostructures were fabricated by a superplastic nano-molding process (see in detail the paper "One-step architecture of crystalline metal by direct nanoscopy with large-melting temperature", published in journal of Nature Communications journal, volume 8, page numbers 1-7, 24, 2017).

Example 1

1) The Au substrate with the Au nano-column array on the surface, which is prepared by superplastic nano-die casting, is fixed on a sample stage of a scanning electron microscope, and a tungsten probe is fixed on a nano manipulator arranged in the scanning electron microscope, wherein the nano manipulator has three-directional freedom degrees and the moving precision can be better than 1 nanometer. Firstly, connecting the tungsten needle tip with the Au substrate through a lead in a short circuit way through the output end of the nanometer manipulator;

2) under the condition that an electron beam of a scanning electron microscope is started (the accelerating voltage of the electron beam is usually set to be more than or equal to 1 kilovolt and less than or equal to 20 kilovolts), a nanometer manipulator is driven to move in situ, so that a tungsten needle point is close to and contacts with one Au nanometer column, then, a tungsten probe is retracted to enable the tungsten probe to be spaced from the Au nanometer column by a certain distance (usually less than 2 micrometers), and meanwhile, a lead between the tungsten needle point and an Au substrate is disconnected, so that the tungsten needle point and the Au substrate are both in an open;

3) the tungsten probe is driven to be close to the Au nano-column, in the process, the Au nano-column is locally melted, the melted Au nano-column can be divided into 2 parts, one part of the Au nano-column is transferred to the tip of the tungsten probe under the action of the electric field force of the tungsten probe and is welded with the tip of the tungsten probe to form the tungsten probe with the Au nano-sphere at the tip (figure 3), and the other tip of the Au nano-column correspondingly forms the nano-sphere.

Example 2

1) Fixing a Pt substrate with a Pt nano-column array on the surface, which is prepared by superplastic nano-die casting, on a sample table of a scanning electron microscope, and enabling the Pt substrate to be in short-circuit connection with a tungsten needle point arranged on a nano manipulator through a lead;

2) under the condition that an electron beam of a scanning electron microscope is started, a nanometer manipulator is driven to move in situ, so that a tungsten needle point is close to and contacts a Pt nanometer column, then a tungsten probe is retracted to enable the tungsten probe to be spaced from the Pt nanometer column by a certain distance (generally smaller than 1 micron), meanwhile, a lead between the tungsten needle point and an Au substrate is cut off, the tungsten needle point and the Pt substrate are respectively connected to a positive electrode and a negative electrode of a voltage source, and the power supply of the voltage source is in a closed state;

3) driving the tungsten probe close to the Pt nanopillar, during which process the Pt nanopillar is locally melted and partially transferred to the tip of the tungsten probe to form a tungsten probe tipped with Pt nanospheres (fig. 4(a) - (b));

4) moving the sample stage, repeating the steps (1) to (3) for other Pt nano-columns, and changing the input ends of the tungsten needle tip and the Pt substrate as follows: by changing the polarity of the tungsten tip or turning on the voltage source, we found that a tungsten tip with a tip welded with a Pt nanostructure could be made.

It is worth pointing out that sometimes the melting phenomenon occurs in the middle of the Pt nano-pillar, so that the tungsten tip-Pt nano-pillar-Pt nano-sphere structure (fig. 5 (a)); with the same probe repeatedly approaching different Pt nano-pillars, more and more Pt nano-structures can be welded at the tip of the tungsten tip (fig. 5(b), fig. 7(a)), while leaving an array of Pt nano-pillars with tips of Pt nano-spheres on the surface of the Pt substrate (fig. 7 (b)).

Example 3

The specific process steps for preparing the typical Pt-Ag nano heterojunction device are as follows:

1) the method steps of the embodiment are adopted, firstly, the tungsten needle tip with the tip welded with the Pt nano column is manufactured;

2) a Pt sample on a scanning electron microscope sample stage is changed into an Ag substrate, and a tungsten needle tip with a tip welded with a Pt nano column is in short circuit connection with the Ag substrate;

3) under the condition that an electron beam of a scanning electron microscope is started, the nanometer manipulator is driven to move in situ, so that the tungsten needle point is close to and contacts an Ag nanometer column on the Ag substrate;

4) disconnecting the short-circuit connection between the tungsten needle tip and the Ag substrate, applying a small voltage between the tungsten needle tip and the Ag substrate, and continuously increasing the input voltage value until the Pt nano column and the Ag nano column are welded;

5) the tungsten needle point is driven to do reciprocating telescopic motion and transverse motion, so that the Ag nano column is fundamentally broken from the connection of the Ag nano column on the Ag substrate, and the tungsten needle point-Pt nano column-Ag nano column heterojunction device is manufactured (figure 6).

Example 4

1) Fixing an Ag substrate with an Ag nano-column array on the surface, which is prepared by superplastic nano-die casting, on a sample stage of a scanning electron microscope, and enabling the Ag substrate to be in short-circuit connection with a tungsten needle point arranged on a nano manipulator through a lead;

2) under the condition that an electron beam of a scanning electron microscope is started, the nanometer manipulator is driven to move in situ, so that the tungsten needle point is close to and contacts an Ag nanometer column;

3) disconnecting the short-circuit connection between the tungsten needle tip and the Ag substrate, applying a small voltage between the tungsten needle tip and the Ag substrate, and continuously increasing the input voltage value until the tungsten needle tip and the Ag nano column are welded;

4) reducing the input voltage to weaken the joule heating effect, so that the welding area is in a solid state, and driving the tungsten needle point to move reversely, so that the welding area is subjected to necking deformation (figure 9 (a));

5) the tungsten tip was driven to continue moving in reverse until the welded region was neck-broken to make a tungsten tip with a sharp tip and an Ag nanopillar tip (fig. 9 (b)).

Example 5

1) Driving the prepared tungsten probe with the tip welded with the Pt nanoball to contact the Pt nanostructure and form a liquid bridge (fig. 10(a) and (c));

2) fixing the Pt nano structure, and driving the tungsten probe to move back;

3) the tungsten probe was withdrawn, the tungsten probe tip and the Pt nanostructure tip shape changed (fig. 10(b) and (d)).

It was found experimentally that the larger the tungsten probe withdrawal speed, the sharper the shape of the obtained nanodevices at the tungsten probe tip and the Pt nanostructure tip (fig. 10(b) and 10 (d)). Wherein, FIG. 10(b) is the drawing of FIG. 10(a) at the retracting speed V₁FIG. 10(d) is the drawing of FIG. 10(c) at the withdrawal speed V₂Is obtained under the conditions of (1) and has V₂>V₁(same withdrawal time, probe in FIG. 10(c) left the field of view of FIG. 10 (d)).

Example 6

1) Preparing a tungsten needle tip (the upper graph of FIG. 11) welded with Pt nanospheres;

2) driving the prepared tungsten needle tip to approach and contact the Pt substrate, and adjusting the potential difference between the tungsten needle tip and the Pt substrate to form a Pt liquid bridge (figure 11, lower graph);

3) maintaining a constant input voltage, driving the tungsten probe to move telescopically so as to change the size of the Pt liquid bridge, and once the size of the Pt liquid bridge is changed, correspondingly changing the monitored current (figure 12 (a));

4) loop resistance and corresponding Pt liquid bridge size were determined (experimental data points in fig. 12 (b));

5) based on equations (5) and (6), the experimental data were fitted to obtain the resistivity of the Pt liquid bridge.

For this example, the resistivity of the Pt liquid was measured to be 1.3 times its solid resistivity at room temperature.

The above embodiments schematically demonstrate that the methods and principles of the present invention can be generally used to tailor various metal nanostructures and assemble into various nanodevices, as well as to electrically characterize the fabricated nanodevices in situ. These nanodevices include, but are not limited to, nanotip probes, nanosphere probes, nanopillar probes, and nanoheterojunctions.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any modification, equivalent replacement, and improvement made by those skilled in the art within the technical scope of the present invention should be included in the scope of the present invention.

Claims

1. A method for cutting and assembling metal nano structure into nano device is characterized by that,

the method is completed in situ under a scanning electron microscope and comprises the following steps:

2. The method of tailoring and assembling of metal nanostructures into nanodevices of claim 1, wherein: the accelerating voltage of the scanning electron microscope is more than or equal to 1 kilo-electron volt.

3. The method of tailoring and assembling of metal nanostructures into nanodevices of claim 1, wherein: the conductive probe is made of W, Ag and Au.

4. The method of tailoring and assembling of metal nanostructures into nanodevices of claim 1, wherein: the shape of the metal nanostructure In the step (1) comprises a rod-shaped, column-shaped, cone-shaped or linear configuration, and the material comprises metals of Au, Cu, Pt, Ag, In, Sn, Bi, Pb, Zn, Al, Pd, Ti, Ni, Co, Fe or alloys thereof.

5. The method of tailoring and assembling of metal nanostructures into nanodevices of claim 1, wherein: the nano device comprises a nano tip probe, a nano sphere probe, a nano column probe, a heterojunction and a combination thereof.

6. The method of claim 1 for tailoring and assembling of generic nanostructures into nanodevices, wherein: and (3) moving the conductive probe to be close to the metal nano structure in the range of 0.1nm-1000 nm.

7. The method of claim 1 for tailoring and assembling nanostructure into a nanodevice, wherein: and (3) the conductive probe is moved through a driving device, and the shape of the nanometer device is modulated by controlling the moving speed of the driving device in the step (2).

8. The method of claim 1 for tailoring and assembling nanostructure into a nanodevice, wherein: the method for cutting and assembling the metal nanostructure into the nano device can be repeatedly implemented, that is, the manufactured nano device is used as a new conductive probe, and the method steps for cutting and assembling the metal nanostructure into the nano device in claim 1 are repeated to form the nano device with the metal nanostructure attached to the tip of the nano device again.

9. The method of claim 1 for tailoring and assembling nanostructure into a nanodevice, wherein: the range of the potential difference U applied between the conductive probe and the metal nano structure after the conductive probe is contacted with the metal nano structure or in the approaching process is more than or equal to 0 and less than or equal to 100 volts.

10. A method for in-situ characterization of the nanodevices of claim 1, comprising the steps of: