RU2400858C1 - Method of producing graphene nano-ribon fet - Google Patents

Abstract

FIELD: electrical engineering. ^ SUBSTANCE: film flat components comprising form-building and functional graphene layers are first fabricated. Note here that said flat film elements are formed on substrate with required spatial arrangement over substrate area, primarily, regular arrangement. Then said flat film elements are separated from substrate and transformed into emitters with preset 3D spatial configuration. Transformation is performed by mechanical internal strains introduced into form-building layers either in producing film flat elements or in transformation, or in their separation and transformation in emitters. ^ EFFECT: uniform emission of electrons over emitters range, required electron emission density, its controllability, scalability of emitter sizes, optimised emitter outline shape and controlled emission current of every emitter. ^ 16 cl, 9 dwg, 7 ex

Description

The invention relates to vacuum electronic devices and can be used to develop technology and in the manufacture of devices for producing an electron beam - cold emitters based on carbon.

Effective sources of cold field emission of electrons in the future have a huge field of application - from electron beam monitors to miniature X-ray sources and light sources. Flat emitter-based monitors may supplant liquid crystal monitors in the near future. Miniature X-ray sources based on carbon emitters will take their place in the scanning systems of non-destructive testing of civil and military applications, in particular: in systems intended for medicine; in security systems; in product quality control systems and production processes. In the field of development and creation of microelectronics, their application in electron microscopy and lithography (alternative sources) is expected.

A known method of forming graphene field emitters (US patent No. 6593683, IPC: 7 H01J 1/02), which consists in the fact that they carry out the ignition of a direct current discharge in a mixture of hydrogen with a carbon-containing additive, heat the substrate and deposit the carbon phase on a substrate located on the anode moreover, a discharge is ignited with a current density of 0.15 ÷ 0.5 A / cm ² , and the deposition is carried out in a mixture of hydrogen with ethyl alcohol or methane vapors at a total pressure of 50 ÷ 300 Torr and heating the substrate to 600 ÷ 900 ° C, at a concentration vapors of ethyl alcohol 5 ÷ 10% and concentration m tana 15 ÷ 30%.

In the particular case, the deposition is carried out by diluting the gas mixture with an inert gas with a content of up to 75% while maintaining full pressure.

There is also a method of forming graphene field emitters (RF patent No. 2161838, IPC: 7 H01J 9/02), which consists in the fact that they carry out the ignition of a microwave discharge with an absorbed power of 5 ÷ 50 W / cm ³ in a mixture of carbon dioxide and methane in the ratio 0.8 ÷ 1.2 at a pressure of 20 ÷ 100 Torr, and the deposition of the carbon phase on the substrate is carried out at a substrate surface temperature of 500 ÷ 700 ° C.

The disadvantages of the above analogues include the heterogeneity of electron emission over the array of emitters, the inability to achieve the desired electron emission density and, as a consequence, the controllability of the emission, the inability to scale the size of the fabricated emitters, the inability to optimize the shape of the emitters (hierarchical structure), the lack of controllability of the emission current of each emitter . The reasons for the shortcomings are as follows.

In the manufacture of graphene field emitters, gas transport epitaxy is used, which leads to the self-formation of randomly arranged graphene flakes of arbitrary shape on the substrate, each of which contains an arbitrary number of graphene monolayers. These graphene flakes form an array. Some of the flakes are oriented vertically and serve as field emitters. The manufacturing process is characterized by: uncontrollability, randomness, size of flakes, their thickness; uncontrolled, disordered arrangement of flakes over the substrate area, that is, complete uncontrollability of the self-formation process. As a result, on the one hand, there are different values of the electric field at the vertices of the emitters and, as a consequence, the heterogeneity of electron emission, the impossibility of setting the required electron emission density and its controllability, the lack of current controllability of individual emitters. On the other hand, the uncontrollability of the self-formation process leads to the inability to scale the size of manufactured emitters and optimize the shape of emitters (hierarchical structure).

As the closest technical solution, a method for forming graphene field emitters (Wu Z.-S., Pei SF, Ren W., Tang D., Gao L., Liu B., Li F., Liu C., and Cheng H. -M. "Field Emission of Single-Layer Graphene Films Prepared by Electrophoretic Deposition" // Adv. Mater. - 2009. - V.21. - PP1756-1760), which consists in the chemical exfoliation of graphite, obtaining particles of graphene less than 30 microns in size and up to 80%, containing a graphene monolayer, after which electrophoretic deposition is carried out, which includes two stages: at the first stage, a liquid-phase suspension containing graphene particles is prepared, h Particles are electrically charged; in the second stage, charged particles are deposited on the surface of a conductive electrode. To obtain a stable graphene suspension, the particles obtained by exfoliation are placed in isopropyl alcohol and sonicated for 1 hour. Then the graphene particles are positively charged by adding Mg (NO ₃ ) ₂ · 6H ₂ O. The weight ratio of graphene particles and the addition of Mg (NO ₃ ) ₂ · 6H ₂ O is 1: 1. As a result of this treatment, a uniform stable suspension of Mg ²⁺ -absorbed graphene particles is obtained. The prepared suspension of Mg ²⁺ -absorbed graphene particles is introduced into the vessel from polymethyl methacrylate as an electrolyte. A stainless steel substrate is used as a positively charged electrode, and a glass plate coated with indium titanium oxide is used as a negatively charged electrode. The distance between the two electrodes is set to 5 mm. A voltage of 100 ÷ 160 V is applied. When a voltage is applied, positively charged graphene particles migrate to the negatively charged electrode and settle on its surface with the formation of an array of graphene particles, fixing on it due to the adhesive properties provided by the presence of Mg ²⁺ . As a result, an array of randomly oriented, disordered graphene particles is formed. Some of them have a spatial orientation that coincides with the normal of the electrode, which is the substrate, protruding beyond its surface, and thus perform the function of emitters.

The disadvantages of the nearest technical solution include the heterogeneity of electron emission over the array of emitters, the inability to achieve the desired electron emission density and, as a consequence, the controllability of the emission, the inability to scale the size of the fabricated emitters, the inability to optimize the shape of the emitters (hierarchical structure), the lack of controllability of the emission current of each from emitters. The reasons for the shortcomings are as follows.

In the manufacture of graphene field emitters, uncontrolled processes are used, with no control over the location of graphene particles on the substrate, no control over their shape, and, strictly speaking, no control over the thickness of particles or the number of graphene monolayers in the particles. On the one hand, the result is different electric field values at the vertices of the emitters and, as a result, the heterogeneity of electron emission, the impossibility of setting the required electron emission density and its controllability, and the lack of current controllability of individual emitters. On the other hand, the uncontrollability of processes, the lack of control, determines the lack of the ability to scale the size of manufactured emitters and optimize the shape of emitters (hierarchical structure).

The technical result of the invention is:

- achieving uniformity of electron emission over an array of emitters;

- achievement of the task of the required electron emission density, emission controllability;

- achieving scalability in the size of manufactured emitters;

- the ability to optimize the shape of emitters (hierarchical structure);

- achieving controllability of the emission current of each of the emitters.

The technical result is achieved in the method of forming graphene field emitters, which consists in the fact that they produce film flat elements containing the forming and functional graphene layers, while flat film elements are formed on the substrate with the desired location along its area, then the film flat elements are separated from the substrate and transform them into emitters with a given three-dimensional spatial configuration due to the action of mechanical internal stresses, which are introduced into the shape these layers either in the manufacture of film flat elements, or in the transformation, or in the separation and transformation of flat elements into emitters, and the material, geometry of the film elements and internal mechanical stresses are selected in the manufacture of film elements providing the possibility of their separation from communication with the substrate and transformation under the action internal mechanical stresses in emitters, which are precision located above the substrate and have a precisely defined spatial configuration and geometric in size.

In the method, when forming flat film elements on the substrate containing the forming and functional graphene layers, all the structural layers of the emitter are fabricated, while using planar technology, lithographs are used to form layer patterns defining the contours of the emitter, the emitter circuit being formed providing partial separation from the substrate,

In the method, solid-state layers are used as forming layers, into which internal mechanical stresses are introduced in the manufacture of film flat elements due to the difference in the constant crystal lattices of materials of solid-state layers, or polymer layers, into which internal mechanical stresses are introduced during separation and transformation or transformation of flat film elements into emitters due to heat treatment carried out using temperatures and duration that cause deformation of the polymer material iala.

In the method, heat treatment uses temperatures from 150 to 200 ° C, and the duration is selected based on the given spatial configuration of the emitters.

In the method, the required arrangement of flat film elements, regular in area of the substrate, is provided by planar technology — lithographically.

In the method, highly oriented pyrolytic graphite, or semiconductor material A ₃ B ₅ —GaAs, or semiconductor material of group IV of the table of D. I. Mendeleev — Si, is selected as the substrate material.

In the method, SiGe / Si, or InGaAs / GaAs, or SiO ₂ / Ni, or SiGe / Si / SiO ₂ / Ni are selected as the material of the forming solid-state mechanically stressed layers of the emitters, and the material of the forming polymer layers of the emitters into which mechanical internal stresses during transformation or during separation and transformation of flat film elements into emitters due to heat treatment, choose polymethyl methacrylate.

In the method, a surface layer of a highly oriented pyrolytic graphite substrate is used as a functional graphene layer, or a graphene layer grown on a donor substrate and transferred to formative layers previously formed on a GaAs or Si substrate, or as a functional graphene layer is used as a functional graphene layer layer use a graphene layer grown directly on the forming layers, pre-formed on a GaAs or Si substrate.

In the method, a surface layer of a highly oriented pyrolytic graphite substrate is used as a functional graphene layer, or a graphene layer grown on a donor substrate and transferred to formative layers previously formed on a GaAs or Si substrate, or as a functional graphene layer is used as a functional graphene layer layer use a graphene layer grown directly on the forming layers, pre-formed on a GaAs or Si substrate.

In the method, the thickness of the film flat element is set from 10 ^-8 to 10 ^-7 m

In the method, during the subsequent separation of the film flat elements from the substrate or during the subsequent separation of the film flat elements from the substrate and their transformation under the influence of internal mechanical stresses into emitters, which are precisely located above the substrate, the material of the element lying under the film flat element is removed, thereby providing an arrangement of emitters above the substrate.

In the method, the sacrificial layer is preliminarily grown on the substrate, the separation of the film flat elements is carried out by selective lateral etching of the sacrificial layer.

In the method, the separation of film flat elements is carried out by selective etching of a substrate using anisotropy of etching.

In the method, AlAs is used as the material of the sacrificial layer.

In the method, in the sacrificial layer, to enable lateral selective etching, lithographic windows are formed with a depth of up to the substrate.

In the method, in the manufacture of film flat elements in which a surface layer of a substrate of highly oriented pyrolytic graphite is used as a functional graphene layer, the substrate is etched to the depth of several atomic layers.

The invention is illustrated by the following description and the accompanying figures. Figure 1 presents an illustration of the principle of precision setting the spatial curvilinear configuration of emitters: a) solid-state layers of materials with different constant lattices in the free state; b) the conjugation of layers on a substrate using pseudomorphic epitaxial growth; c) the separation of layers from the substrate under the action of internal mechanical stresses during selective lateral etching of the sacrificial layer with the location of the separated part outside the substrate, where 1 is the InP substrate; 2 - InAs forming layer; 3 - GaAs forming layer; 4 - sacrificial layer of AlAs. Figure 2 schematically shows the result of lithographic manufacturing in a multilayer graphene / Si / SiGe film of windows that determine the geometry of the film elements regularly located on the substrate, and which determine the possibility of separation of the film elements from communication with the substrate during transformation into emitters with a precisely identical spatial configuration and geometric size; the windows are made in the form of segments converging at an angle, forming a "herringbone", located relative to each other at the same distance, film elements are located between the windows-segments. Figure 3 schematically shows the result of separating film-shaped flat elements manufactured lithographically in a multilayer graphene / Si / SiGe film and transforming them under the influence of internal mechanical stresses into emitters located precisely above the substrate. Figure 4 presents a schematic illustration of graphene emitters, "bent" by mechanically strained forming layers to reach a plane parallel to the plane of the substrate (horizontal emitters); Electrons in microvacuum devices are emitted to the anode in a plane parallel to the substrate. Figure 5 shows a photograph of the result of the experimental implementation of graphene emitters with forming SiGe / Si layers of a regular "Christmas tree" arrangement on a substrate; the windows are made in the form of densely spaced segments converging at an angle, forming a "herringbone", by electronic lithography. Figure 6 shows a photograph of the result of the experimental implementation of graphene emitters with forming SiGe / Si layers, in which the tips of the needle-shaped emitters are made with a geometric configuration in the form of the letter "M"; The photo illustrates the simplest case of the hierarchical structure of emitters. Figure 7 shows a photograph of a dense array of graphene field emitters obtained by lithographic production of a cross-shaped pattern of windows in the film structure containing structural layers defining the geometry of film flat elements regularly located on the substrate and specifying the possibility of separating the film elements from communication with the substrate during transformation into emitters with a precisely defined spatial “south” - “west” - “north” - “east” configuration and geometric dimensions. On Fig shows a photograph of an array of graphene field emitters with a precisely defined spatial "south" - "west" - "north" - "east" configuration and geometric dimensions; between the rows of emitters there are rows of pads (light areas in the photo), on which it is possible to form integrated circuit elements controlling emitters in the substrate. Figure 9 shows photographs of the result of the experimental implementation of graphene emitters with SiGe / Si forming layers of a regular "Christmas tree" arrangement on a substrate; the windows are made in the form of optical lithography converging approximately at right angles to the “herringbone” segments: a) image of a separate emitter; b) image of an array of emitters.

It is well known that the most promising are emitters based on carbon. Over the past fifteen years, developments have been continuously ongoing to create emitters based on carbon nanotubes.

Graphene, as an object with which you can work, appeared 5 years ago. In 2009, it became clear that using existing growth methods, it is possible to obtain fairly uniform graphene layers over large areas and in a relatively cheap way - by epitaxy from the gas phase (Kim K.S., Zhao Y., Jang H., Lee SY, Kim JM , Kim KS, Ahn J.-H., Kim P., Choi J.-Y., Hong BH "Large-scale pattern growth of graphene films for stretchable transparent electrodes" // Nature. - 2009. - V.457. - P.07719; Alfonso Reina, Xiaoting Jia, John Ho, Daniel Nezich, Hyungbin Son, Vladimir Bulovic, Mildred S. Dresselhaus and Jing Kong "Large Area, Few-Layer Graphene Films on Arbitrary Substrates by Chemical Vapor Deposition" // Nano Lett., 2009 v.9 (1) pp30-35; Alfonso Reina, Stefan Thiele, Xiaoting Jia, Sreekar Bhaviripudi, Mildred S. Dresselhaus, Juergen A. Schaefer and Jing Kong “Growth of Large-Area Single- and Bi-Layer Graphene by Controlled Carbon Precipitation on Polycrystalline Ni Surfaces ”// Nano. Res., (2009), 2: p.p.509-516). This leads to seriously consider graphene films as a basic object for the manufacture of various devices by industrial technology.

It is obvious that cold field emission from a monolayer graphene film is of great interest and has the prospect of creating emitters.

The problem of obtaining graphene films of a large area on substrates has practically been solved using transport gas epitaxy. However, the problem of creating arrays of emitters spatially above the substrate on a substrate from flat graphene layers has not yet been considered. This problem is interesting in that its solution - the creation of a dense array of graphene emitters with strictly specified dimensions and location in space, eliminates the problems associated with the use of carbon tubes for forming emitters.

A key issue in the production of flat screens, X-ray sources, and other devices based on the use of cold emitters based on carbon tubes is the achievement of uniformity of emission over the area, high density of elements, providing the desired emission density. There is still no methodology for the manufacture of vertical precision needles or tubes that act as emitters. At the same time, to date, a method for producing graphene over large areas, more than 200 cm ^2, has already been developed. Using the method of growing graphene layers from hydrocarbons, it is guaranteed to obtain layers on a washer measuring 10 × 10 cm ² . Moreover, it is obvious that a layer of graphene can be grown on a much larger area, which is a prerequisite for the possibility of creating high-format flat-panel monitors or displays of a new generation.

In the proposed technical solution, the shape of the emitters is given by lithography. To implement the most diverse arrays of emitters, a traditional single-level photolithography and / or nanolithography is taken. Until 2009, nanolithography was considered as an expensive technological tool working with very small areas (of the order of several cm ² ). However, the creation by now of continuous stamped imprint lithography makes it possible to quickly and cheaply form lithographic drawings in vast areas. In (Ahn SH, Guo LJ, “Large Area Roll-to-Roll and Roll-to-Plate Nanoimprint Lithography: a Step Toward High-Throughput Application of Continuous Nanoimprinting” // ACSNANO. - 2009. - V.3 (8 ). - PP2304-2310) the possibility of already continuous nanoimprint lithography is reported. The use of such lithography makes it possible to manufacture, using the proposed method, cheap graphene displays of meter or multimeter sizes. Note that the process of growing graphene from the gas phase also belongs to low-cost processes and can be carried out on large areas.

On the other hand, the feasibility of the proposed technical solution is based on the achievements of recent years in the field of thin film technology.

We propose a method for converting flat graphene films into a well-organized array of needle-shaped and / or tubular emitters. The proposed method fits in with well-developed integrated circuit technology. The method allows for complete control of the processes of formation of the most diverse configurations of emitters.

It is expected that the use of the present invention will provide the formation of arrays of graphene emitters, in particular, needle-type type of a given density, for example, 10 ⁸ cm ^-2 .

In the proposed method for the formation of graphene field emitters, the achievement of a technical result is based on the following premises.

Firstly, on the possibility of a controlled transition from two-dimensional, flat, film elements, which are emitter blanks, to three-dimensional ones.

Secondly, on the possibility of achieving the desired location of the emitters in area, as well as in space, which can vary widely from strictly regular to characterized by the absence of any regularity.

Thirdly, on the possibility of precision setting the size and shape of emitters.

Fourth, the use of materials and methods of a well-developed planar technology for the manufacture of integrated circuits.

A graphene layer or several graphene layers are functional layers in electron field emitters and provide emission. Therefore, the control of the precise arrangement in the space of emitters in combination with the strict specification of their sizes and spatial configurations opens up new possibilities both in using arrays of emitters and in achieving a maximum density and a minimum threshold for electron emission.

The formation of emitters begins with the manufacture of a film-containing structure containing the structural layers located on the substrate by methods and using materials of planar industrial technology of semiconductor devices. This technology also allows the formation of precision micro- and nanoelements - film flat elements, which are emitter blanks, from the original film structure containing structural layers with a given density, with the required location on the substrate and the desired geometric configuration (micro-, nanolithographic methods, including imprint lithography ) The next step in the formation of emitters is to detach the film flat element from the substrate and change its spatial configuration under the action of elastic forces arising from the presence of forming layers into which internal mechanical stresses are introduced and which are coupled to a graphene layer. Mechanical internal stresses are introduced into the forming layers at the manufacturing stage of the film-containing film structure or at the stage of detachment and transformation or transformation of the film flat element, leading to a change in its spatial configuration.

A precise determination of the spatial configuration of emitters is possible, firstly, on the principles of the formation of micro- and nanoshells from planar initially strained heterofilms developed by V.Ya. Prinz et al. (V.Ya.Prinz, VASeleznev, A.K. Gutakovsky, AVChehovskiy , VV Preobrazenskii, MAPutato, TAGavrilova "Free-standing and overgrown InGaAs / GaAs nanotubes, nanohelices and their arrays". Physica E, 2000 v.6, N 1-4, pp828-831). A precise determination of the spatial configuration of the emitters is also possible when micro- and nanoshells are formed from flat films that initially do not have internal mechanical stresses, but which can be introduced into them after they are grown on the substrate by means of deformation treatments, for example, heat treatments that cause material shrinkage. An illustration of the principle on the example of the formation of a shell from a flat film of solid materials containing mechanically stressed layers of InAs and GaAs is shown in FIG.

On the substrate (1), for example, from a single-crystal InP, previously coated with a sacrificial layer (4) AlAs, a film element is made containing mechanically stressed layers (2) and (3), for example, InAs and GaAs, respectively (see Fig. 1a)). Moreover, in the case of the above materials, layers (2) - (4) are formed by epitaxy, observing the conditions of pseudomorphic growth, that is, each successively grown layer inherits a constant lattice of the substrate (1) (see Fig. 1b)). Since in the free state, the GaAs lattice constant (5.654 Å) is smaller than the InP lattice constant (5.869 Å), as schematically shown in Fig. 1a), the GaAs forming layer (3) is elastically stretched, respectively, the InAs forming layer (2) , which in the free state has a larger lattice constant (6.058 Å) than InP, is elastically compressed. The elastic forces F ₁ and F ₂ in the forming layers (2) and (3) (Fig. 1c)) of the film element are directed in opposite directions and create a moment of forces M, which tends to bend the InAs / GaAs film, but it is rigidly connected to the substrate ( 1) using the sacrificial layer (4) and therefore is kept in a flat state. With directed lateral etching of the sacrificial layer (4) AlAs, the film from the forming layers (2) and (3) is separated from the substrate (1) and bends under the action of the moment M of elastic deformation, acquiring a shape corresponding to the minimum energy of internal mechanical stresses (Fig.1c )). In this case, the radius of curvature of the bend r is reproduced with precision accuracy, since it is defined by a strictly defined relative mismatch of the periods of the crystal lattices δ and the thicknesses of the forming layers d ₁ and d ₂ , which are specified up to monoatomic layers during epitaxial growth

r = (1/6) · [(d ₁ + d ₂ ) ³ (δd ₁ d ₂ )].

A similar situation occurs when growing a film containing formatively mechanically stressed layers directly on a substrate without a sacrificial layer and separating the film from the substrate by selective etching of the latter.

Thus, the precision setting of the spatial configuration of emitters made using solid-state layers is ensured by the presence of mechanically stressed forming layers (2) and (3) (see Fig. 1c) of a given thickness and composition. The creation of these formative layers is carried out at the stage of forming a multilayer film flat element through the wide possibilities of planar technology.

To obtain mechanically stressed formative layers providing uniformity of the layer thickness and uniformity of mechanical stresses across the layer, methods of planar technology such as epitaxy, electrochemical deposition, and vacuum deposition are used. Separating the film element containing the strained forming layers (2) and (3) (Fig. 1c)) from the substrate (1), it is transformed into a shell with a given local curvature or, more generally, into a shell with a given spatial configuration, which can be varied over a wide range. A specific value of the local curvature of the shell, or a specific spatial configuration of the emitter, is set with high precision by the choice of internal stresses between the forming layers (2) and (3), the thicknesses and mechanical properties of the materials of the layers.

The proposed method for the formation of graphene field emitters allows you to implement a wide variety of patterns of the forming and functional layers of the emitters in the manufacture of the film element, as well as use a wide range of materials for the manufacture of structural layers of emitters with a precise selection of their thicknesses and internal mechanical stresses in order to obtain one or another local curvature, or one or another spatial configuration of the emitters. Materials for forming layers can be not only semiconductors, but also conductive materials - metals, and dielectric materials. The work (Nastaushev Yu. V., Prinz V. Ya., And Svitasheva SN “A technique for fabricating Au / Ti micro- and nanotubes”. - Nanotechnology, 2005, 16, pp908-912) demonstrates the use of metal layers for forming tubular structures according to the above principle. In some cases, the manufacture of emitters, for example, to organize effective heat removal, it is advisable to use metal forming layers. As dielectric materials, the use of polymers is possible. A two-layer film containing a layer of a stretched or compressed polymer is also bent when it is disconnected from the substrate and is transformed from a flat state to a three-dimensional state with the possibility of precision setting its spatial configuration.

On the other hand, a forming layer made of a polymeric material may initially not have the internal mechanical stresses necessary for the transformation of a film flat element into a shell. They are introduced, for example, by heat treatment, leading to the shrinkage of the polymeric material and the emergence of elastic forces similar to the forces F ₁ and F ₂ (Fig. 1c), creating a moment of forces tending to bend the graphene / polymer film, which is either partially free from the substrate and is in a "suspended" flat state above the substrate, or is rigidly connected with the substrate. In the first case, the acting elastic forces work to bend the portion of the film flat element freed from communication with the substrate in such a way that it begins to protrude above the substrate, taking the spatial configuration required for the emitter. In the second case, the arising elastic forces work to “detach” the graphene layer from the substrate and bend the film flat element that is “detached” from the substrate. Under the action of the moment of elastic deformation forces, the film flat element bends, acquiring a shape corresponding to the minimum energy of internal mechanical stresses. The bending radius of curvature is also reproduced with precision accuracy, since it is defined by strictly defined heat treatment temperatures and their duration, material and thickness of the forming polymer layers.

With regard to the adhesion or fixing of graphene layers on the forming layers, the question is solved as follows.

First, using the forces of Van der Waltz, it is possible to fix a graphene layer on semiconductor films. In this case, the graphene layer remains in a fixed state under tensile or compression strains reaching up to 1%.

Secondly, using for fixing nanoglue. In particular, the graphene layer is connected to the forming layers by means of a monolayer adhesive.

Thirdly, by growing graphene layers conjugated with the forming layers. Thus, methods are known for growing graphene layers on metal films, as well as the formation of a graphene layer by evaporation of Si atoms from a SiC semiconductor film.

Fourth, by “pressing” a graphene layer into the polymer while fixing it on the polymer film.

The simplest option for fixing graphene and polymer layers is to place a graphene layer between two polymer layers, the bottom is compressed, and the top is stretched.

The proposed method for forming emitters, in General, consists of two stages.

The content of the first stage consists in the formation of film-containing flat elements containing layers on the substrate, which are emitter blanks. Moreover, the elements are formed on the position with the desired location, in the particular case, regular. These elements contain formative and functional layers. Functional layers are graphene layers. Forming layers are initially mechanically strained solid-state or polymer layers, or initially mechanically unstressed polymer layers, into which internal mechanical stresses are introduced only after their manufacture, subjecting them to additional deforming treatments. The material, the geometry of the film element and internal mechanical stresses are selected to provide the possibility of separating them from communication with the substrate and transformation under the action of internal mechanical stresses into emitters, which are precisely located above the substrate. In this case, the emitters being manufactured are given a precisely defined, in particular, identical spatial configuration and geometric dimensions. The result of the first step is illustrated in FIG.

When forming flat film elements on a substrate containing at least one form-forming and functional graphene layer in their composition, all emitter structural layers are made. When using solid-state layers, at least two forming layers are grown mechanically stressed relative to each other. Moreover, the functional layer can also be simultaneously forming. The thickness of each layer is set in the range from a few microns to one atomic monolayer. In the particular case, a sequence of forming layers (in the limiting case of a monomolecular or monoatomic thickness) can be performed with individually specified mechanical stresses, so that a film is formed by this sequence of layers, in the transverse direction of which a gradient of longitudinal mechanical stresses is specified.

Further, by means of planar technology, lithographs are formed of layer patterns defining the contours of the emitter, at the same time, they set the required location of future emitters by area. Moreover, the emitter circuit is formed to provide its partial separation from the substrate and the location outside the plane of the substrate under the action of internal mechanical stresses introduced into the forming layers during their manufacture or after (see Figure 3-9). The simplest pattern for all layers of film flat elements can be a herringbone pattern covering the entire surface of the substrate (see Figs. 2-5, Fig. 9). A more complex pattern of layers defining the contours of the emitter is implemented when windows are configured in the form of the letter “M”;

the film flat element has an M-shaped configuration, and after separating it from the substrate and transforming into an emitter, the top of the emitter also has an M-shape (see Fig. 6), while in the array the emitters are spatially identically oriented and absolutely identical in all other parameters , as well as strictly regularly located in relation to the area of the substrate. Another complex pattern of layers, defining the contours of the emitter, is implemented when executing cross-shaped windows; in each of the four manufactured emitters are spatially oriented according to the type “south” - “west” - “north” - “east”, but the geometric dimensions and curvature of the emitters are the same (see Fig. 7 and 8). Using etching (traditional chemical, plasma), the pattern is transferred to a depth sufficient to form windows in the structural layers that provide access to the selective etchant to the underlying material of the sacrificial layer. The role of the sacrificial layer can be performed by the substrate. Partial separation of the film flat element can be performed without etching the sacrificial layer or substrate, by “tearing” the graphene layer from the substrate. In this case, the pattern is transferred to the depth of several atomic layers of the substrate of highly oriented pyrolytic graphite. The depth of transfer of the pattern sets the thickness of the separated layer of graphene, which is the structural layer of the emitter, from the substrate.

In the method, it is sufficient to use simple single-level lithography. Among the more advanced lithographic methods, nanolithography, stamping is the simplest and most suitable for mass industrial technology. Today, the level of development of the stamp technology is such that the working state of the stamp is preserved when it is used to form 1 million prints in the resist, which ensures low cost lithography.

The content of the second stage is to separate the film flat elements from the substrate with their transformation into emitters with a given three-dimensional spatial configuration (see Figure 3-9). A specific three-dimensional spatial configuration of the manufactured emitters is specified at the first stage in the manufacture of a film containing the forming and functional layers of the film, from which film flat elements are lithographically formed (see Figure 2). The contours of film flat elements - blanks of emitters, in a particular case, form a “herringbone” pattern on the substrate.

It is important to emphasize once again that the proposed method for the formation of graphene field emitters is integrated with integrated circuit technology, which makes it possible to produce an emission control device in integrated design with an array of emitters or, moreover, in integrated design with each of the emitters. In particular, the array of emitters can be made in the form of a hierarchical structure with the ability to select the supply of control voltage to specific emitters of the array (see Fig.6, Fig.8).

As information confirming the possibility of implementing the method with the achievement of a technical result, we give the following implementation examples.

Example 1

On a GaAs substrate with an orientation of (100), film flat elements are made containing the forming and functional graphene layers. Flat film elements are formed on a substrate with a desired location over its area. Then the film flat elements are separated from the substrate and transform them into emitters with a given three-dimensional spatial configuration due to the action of mechanical internal stresses that are introduced into the forming layers in the manufacture of film flat elements. The material, the geometry of the film elements and the internal mechanical stresses are selected in the manufacture of the film elements, providing the possibility of their separation from communication with the substrate and transformation under the action of internal mechanical stresses into emitters, which are precisely located above the substrate and have a precisely defined spatial configuration and geometric dimensions.

When film flat elements containing a forming and functional graphene layers are formed on a substrate, all emitter structural layers are made, and, using planar technology, lithographs are used to form layer patterns defining the emitter contours, and the emitter contour is formed to ensure its partial separation from the substrate.

The required arrangement of film flat elements, not strictly regular in area of the substrate, is provided by planar technology - lithographically.

As the forming layers, solid-state layers are used, into which internal mechanical stresses are introduced in the manufacture of flat film elements due to the difference in the constant crystal lattices of the materials of the solid-state layers.

As the material of mechanically strained solid-state layers, which are the forming emitters, choose In _0.2 Ga _0.8 As / GaAs.

The thickness of the film flat element set 10 ^-7 m

In the manufacture of a film flat element on a substrate, these formative layers are first formed in a sequence of In _0.2 Ga _0.8 As, and then from GaAs, with a layer thickness of 9 nm, after which a graphene layer freed from bond with the substrate is transferred, which is preliminarily grown on a nickel film and disconnected from it in a selective etchant — a 30% FeCl ₃ solution.

The In _0.2 Ga _0.8 As forming layer is formed compressed relative to the substrate as a result of pseudomorphic growth. Due to the anisotropy of the Young's modulus when separating the film flat element from the substrate, it is energetically most advantageous to bend the layers upon transformation into the spatial configuration of emitters in crystallographic directions of the type <010>.

Lithographically form layer patterns defining the contours of the emitter in the form of an angle with a vertex oriented along the <010> direction. Lithographic windows defining the patterns of the layers and defining the contours of the emitter, made in the form of slits-segments, forming an angle with the apex along the indicated direction, are made by liquid etching using an etchant based on phosphoric acid.

Film flat elements are separated from the substrate with their transformation into emitters with a given three-dimensional spatial configuration. When separating the film elements from the substrate and transforming them under the action of internal mechanical stresses into emitters, which are precision located above the substrate, the material of the element lying under the film flat element is removed, thereby ensuring the location of the emitters above the substrate. To do this, the sacrificial layer is preliminarily grown on the substrate, the separation of the film elements with transformation is started from the angle that is formed by the slits-segments, and is carried out by side selective etching of the sacrificial layer. AlAs is used as the material of the sacrificial layer. A 20 nm thick AlAs sacrificial layer is formed pseudomorphically before growing the forming layers. In the sacrificial layer, to enable lateral selective etching, lithographic windows with a depth of up to the substrate are formed. Etching is carried out until the partial separation of the film flat elements and transforming them into emitters.

Curved needle-shaped emitters made on a substrate, strictly spatially oriented above it, are interconnected by sections of layers grown on the substrate during the formation of film flat elements, which remain on it after partial separation of film flat elements from the substrate.

Example 2

On a substrate of lightly doped Si with an orientation of (100), film flat elements are made containing the forming and functional graphene layers. Flat film elements are formed on a substrate with a desired location over its area. Then the film flat elements are separated from the substrate and transform them into emitters with a given three-dimensional spatial configuration due to the action of mechanical internal stresses that are introduced into the forming layers in the manufacture of film flat elements. The material, the geometry of the film elements and the internal mechanical stresses are selected in the manufacture of the film elements, providing the possibility of their separation from communication with the substrate and transformation under the action of internal mechanical stresses into emitters, which are precisely located above the substrate and have a precisely defined spatial configuration and geometric dimensions.

When film flat elements containing a forming and functional graphene layers are formed on a substrate, all emitter structural layers are made, and, using planar technology, lithographs are used to form layer patterns defining the emitter contours, and the emitter contour is formed to ensure its partial separation from the substrate.

The required arrangement of film flat elements, regular in area of the substrate, is provided by planar technology - lithographically.

As the forming layers, solid-state layers are used, into which internal mechanical stresses are introduced in the manufacture of flat film elements due to the difference in the constant crystal lattices of the materials of the solid-state layers.

As the material of mechanically strained solid-state layers, which are the forming emitters, choose Si _0.8 Ge _0.2 / Si. Forming layers are heavily doped with boron to a concentration of 10 ²⁰ cm ^-3 .

The thickness of the film flat element set 6.2 · 10 ^-8 m

In the manufacture of a film flat element on a substrate, these formative layers are first formed in a sequence of Si _0.8 Ge _0.2 , and then Si, 12 nm and 50 nm thick, respectively, and then “glued” to the last the well-known method (Hailiang Wang, Xinran Wang, Xiaolin Li, Hongjie Dai "Chemical Self-Assembly of Graphene Sheets", Nano Res (2009) 2: 336-342), a layer of graphene that was previously grown on a nickel substrate, freed from bonding and disconnected from it in a selective etchant - 30% solution of FeCl ₃ .

The forming layer of Si _0.8 Ge _{0.2 is} formed compressed relative to the substrate as a result of pseudomorphic growth. Due to the anisotropy of the Young's modulus when separating the film flat element from the substrate, it is energetically most advantageous to bend the layers upon transformation into the spatial configuration of emitters in crystallographic directions of the <100> type.

Lithographically form layer patterns defining the contours of the emitter in the form of an angle with a vertex oriented along the <110> direction. Lithographic windows defining the patterns of the layers and defining the contours of the emitter, made in the form of slits-segments forming an angle with the apex along the indicated direction, are made by reactive-ion etching using: for a layer of graphene plasma-chemical etching in O ₂ ; for heavily doped with boron SiGe / Si reactive-ion etching in CF ₄ + O ₂ .

Film flat elements are separated from the substrate with their transformation into emitters with a given three-dimensional spatial configuration. When separating the film elements from the substrate and transforming them under the action of internal mechanical stresses into emitters, which are precision located above the substrate, the material of the element lying under the film flat element is removed, thereby ensuring the location of the emitters above the substrate. The separation of the film elements begins from the top of the angle, which is formed by slits, segments, and is carried out by selective etching of the substrate using etching anisotropy in a solution of ammonia (NH ₄ OH: H ₂ O - 1: 5). Etching is carried out until the partial separation of the film flat elements and transforming them into emitters.

Curved needle-shaped emitters made on a substrate, strictly spatially oriented above it, are interconnected by sections of layers grown on the substrate during the formation of film flat elements, which remain on it after partial separation of film flat elements from the substrate.

The examples of the implementation of the method relate to the manufacture of emitters of micron sizes. In the manufacture of nanometer-sized emitters, an additional supercritical drying operation of the structure in CO ₂ is carried out, which is final. This drying eliminates the deformation of needle emitters due to the action of capillary forces.

Example 3

On a substrate of lightly doped Si with an orientation of (100), film flat elements are made containing the forming and functional graphene layers. Flat film elements are formed on a substrate with a desired location over its area. Then the film flat elements are separated from the substrate and transform them into emitters with a given three-dimensional spatial configuration due to the action of mechanical internal stresses that are introduced into the forming layers in the manufacture of film flat elements. The material, the geometry of the film elements and the internal mechanical stresses are selected in the manufacture of the film elements, providing the possibility of their separation from communication with the substrate and transformation under the action of internal mechanical stresses into emitters, which are precisely located above the substrate and have a precisely defined spatial configuration and geometric dimensions.

When film flat elements containing a forming and functional graphene layers are formed on a substrate, all emitter structural layers are made, and, using planar technology, lithographs are used to form layer patterns defining the emitter contours, and the emitter contour is formed to ensure its partial separation from the substrate.

The required arrangement of film flat elements, regular in area of the substrate, is provided by planar technology - lithographically.

As the forming layers, solid-state layers are used, into which internal mechanical stresses are introduced in the manufacture of flat film elements due to the difference in the constant crystal lattices of the materials of the solid-state layers.

As the material of mechanically strained solid-state layers, which are the forming emitters, choose Si _0.8 Ge _0.2 / Si / Cr / SiO ₂ / Ni. The shaping layers of Si _0.8 Ge _0.2 and Si are heavily doped with boron to a concentration of 10 ²⁰ cm ^-3 .

The thickness of the film flat element set 2.2 · 10 ^-7 m

In the manufacture of a film flat element on a substrate, first these gas-forming layers are formed by gas transport epitaxy in the sequence of Si _0.8 Ge _0.2 with a thickness of 12 nm, then Si with a thickness of 50 nm and a Cr layer with a thickness of 20 nm, after which a layer is formed on the latter SiO ₂ with a thickness of 2 nm, on which a 150 nm thick Ni layer is sprayed. The structure is placed in a quartz reactor to form a graphene layer. After pumping the quartz reactor with a fore-vacuum pump, a mixture of argon and hydrogen is launched into it and the temperature is raised to 900 ° C, then a mixture of argon, methane and hydrogen in the proportions of 100: 30: 20 is passed for 3 minutes. Next, the reactor is cooled at a rate of 3 ° C / sec, which leads to the formation of a graphene layer on the surface of the nickel layer in a thickness of 3 or in separate sections 4 of the monolayer. The number of monolayers is determined from the Raman spectra of the amplitude and width of the peaks 2D (2700 cm ^-1 ) and G (1580 cm ^-1 ).

The forming layer of Si _0.8 Ge _{0.2 is} formed compressed relative to the substrate as a result of pseudomorphic growth. Due to the anisotropy of the Young's modulus when separating the film flat element from the substrate, it is energetically most advantageous to bend the layers upon transformation into the spatial configuration of emitters in crystallographic directions of the <100> type.

Lithographically form patterns of layers (see Figure 2), defining the contours of the emitter in the form of an angle with a vertex oriented along the direction <110>. Lithographic windows defining the patterns of the layers and defining the contours of the emitter, made in the form of slits-segments that form an angle with the apex along the indicated direction, are made by etching using: for a layer of graphene plasma-chemical etching in O ₂ ; for a nickel layer of etching in a 30% aqueous solution of FeCl ₃ at a temperature of 30 ° C; for heavily doped boron SiGe / Si layers of reactive ion etching in CF ₄ + O ₂ ; for the SiO ₂ layer is also reactive ion etching in CF ₄ + O ₂ .

Film flat elements are separated from the substrate with their transformation into emitters with a given three-dimensional spatial configuration. When separating the film elements from the substrate and transforming them under the action of internal mechanical stresses into emitters, which are precision located above the substrate, the material of the element lying under the film flat element is removed, thereby ensuring the location of the emitters above the substrate. The separation of the film elements starts from the angle formed by the slits, and is carried out by selective etching of the substrate using etching anisotropy in an ammonia solution (NH ₄ OH: H ₂ O - 1: 5). Etching is carried out until the partial separation of the film flat elements and transforming them into emitters. The etching is stopped after reaching a predetermined bend of the film element when it is transformed into an emitter and the emitter is oriented in the vertical direction (see FIG. 3).

Curved needle-shaped emitters made on a substrate (see FIG. 3), strictly spatially oriented above it, are interconnected by sections of layers grown on a substrate during the formation of film flat elements that remain on it after partial separation of film flat elements from the substrate.

Example 4

On a substrate of lightly doped Si with an orientation of (100), film flat elements are made containing the forming and functional graphene layers. Flat film elements are formed on a substrate with a desired location over its area. Then the film flat elements are separated from the substrate and transform them into emitters with a given three-dimensional spatial configuration due to the action of mechanical internal stresses that are introduced into the forming layers in the manufacture of film flat elements. The material, the geometry of the film elements and the internal mechanical stresses are selected in the manufacture of the film elements, providing the possibility of their separation from communication with the substrate and transformation under the action of internal mechanical stresses into emitters, which are precisely located above the substrate and have a precisely defined spatial configuration and geometric dimensions.

When film flat elements containing a forming and functional graphene layers are formed on a substrate, all emitter structural layers are made, and, using planar technology, lithographs are used to form layer patterns defining the emitter contours, and the emitter contour is formed to ensure its partial separation from the substrate.

The required arrangement of film flat elements, regular in area of the substrate, is provided by planar technology - lithographically.

As the forming layers, solid-state layers are used, into which internal mechanical stresses are introduced in the manufacture of flat film elements due to the difference in the constant crystal lattices of the materials of the solid-state layers.

As the material of mechanically strained solid-state layers, which are the forming emitters, choose Si _0.8 Ge _0.2 / Si / SiO ₂ / Ni. The shaping layers of Si _0.8 Ge _0.2 and Si are heavily doped with boron to a concentration of 10 ²⁰ cm ^-3 .

The thickness of the film flat element set 2.2 · 10 ^-7 m

In the manufacture of a film flat element on a substrate, first these gas-forming epitaxy layers are formed in the sequence — from Si _0.8 Ge _0.2 with a thickness of 12 nm, then from Si with a thickness of 50 nm, after which a 1 nm thick SiO ₂ layer is formed on the substrate, on which a 150 nm thick Ni layer is sprayed.

Prior to the deposition of a graphene layer, layer patterns are formed lithographically defining the emitter contours in the form of an angle with a vertex oriented along the <110> direction. Lithographic windows defining the patterns of layers and defining the contours of the emitter, made in the form of slits-segments forming an angle with a vertex along the indicated direction, are made by reactive-ion etching using: for a nickel layer etching in a 30% aqueous solution of FeCl ₃ at a temperature of 30 ° FROM; for heavily doped boron SiGe / Si layers of reactive ion etching in CF ₄ + O ₂ ; for the SiO ₂ layer is also reactive ion etching in CF ₄ + O ₂ .

The structure is placed in a quartz reactor to form a graphene layer on the non-etched portions of the nickel layer. After pumping the quartz reactor with a fore-vacuum pump, a mixture of argon and hydrogen is launched into it and the temperature is raised to 900 ° C, then a mixture of argon, methane and hydrogen in the proportions of 100: 30: 20 is passed for 3 minutes. Next, the reactor is cooled at a rate of 3 ° C / sec, which leads to the formation of a graphene layer on the surface of the nickel layer with a thickness of 3 or in separate sections of 4 monolayers. The number of monolayers is determined from the Raman spectra of the amplitude and width of the peaks 2D (2700 cm ^-1 ) and G (1580 cm ^-1 ).

The forming layer of Si _0.8 Ge _{0.2 is} formed compressed relative to the substrate as a result of pseudomorphic growth. Due to the anisotropy of the Young's modulus when separating the film element from the substrate, the most flexible is the bending of the layers during transformation into the spatial configuration of emitters in crystallographic directions of the <100> type.

Film flat elements are separated from the substrate with their transformation into emitters with a given three-dimensional spatial configuration. When separating the film flat elements from the substrate and transforming them under the action of internal mechanical stresses into emitters that are precisely located above the substrate, the material of the element lying under the film flat element is removed, thereby ensuring the location of the emitters above the substrate. The separation of film flat elements starts from the angle formed by the slits, and is carried out by selective etching of the substrate using etching anisotropy in an ammonia solution (NH ₄ OH: H ₂ O - 1: 5). Etching is carried out until the partial separation of the film flat elements and transforming them into emitters.

Curved needle-shaped emitters made on a substrate, strictly spatially oriented above it, are interconnected by sections of layers grown on the substrate during the formation of film flat elements, which remain on it after partial separation of film flat elements from the substrate.

With respect to the structure containing graphene field emitters made according to the method described in Example 4, measurements of the emission current were performed. The measurements were carried out in a vacuum installation at a vacuum level of 10 ^-4 ÷ 10 ^-5 Pa, the distance between the electrodes was 80 μm. The threshold field of the onset of emission was 2 V / μm (at a current of the order of 100 μA / cm ² ). Such a low threshold voltage is characteristic of carbon tubes and graphene. The dependence of the emission current density on the electric field was measured on this structure. With an electric field of 3 V / μm, the current was 1 mA / cm ² ; at 5 V / μm - 10 mA / cm ² ; at 6 V / μm - 28 mA / cm ² ; at 7 V / μm - 95 mA / cm ² ; at 9 V / μm - 0.5 A / cm ² . No changes in the emission current were detected during the 46 hours of testing; the operation of the cathodes, in particular, at E = 5.5 V / μm and an emission current of 15 mA / cm ^{2 is} stable.

Example 5

On a substrate of lightly doped Si with an orientation of (100), film flat elements are made containing the forming and functional graphene layers. Flat film elements are formed on a substrate with a desired location over its area. Then the film flat elements are separated from the substrate and transform them into emitters with a given three-dimensional spatial configuration due to the action of mechanical internal stresses that are introduced into the forming layers in the manufacture of film flat elements. The material, the geometry of the film elements and the internal mechanical stresses are selected in the manufacture of the film elements, providing the possibility of their separation from communication with the substrate and transformation under the action of internal mechanical stresses into emitters, which are precisely located above the substrate and have a precisely defined spatial configuration and geometric dimensions.

When film flat elements containing a forming and functional graphene layers are formed on a substrate, all emitter structural layers are made, and, using planar technology, lithographs are used to form layer patterns defining the emitter contours, and the emitter contour is formed to ensure its partial separation from the substrate.

The required arrangement of film flat elements, regular in area of the substrate, is provided by planar technology - lithographically.

As the forming layers, solid-state layers are used, into which internal mechanical stresses are introduced in the manufacture of flat film elements due to the difference in the constant crystal lattices of the materials of the solid-state layers.

As the material of mechanically strained solid-state layers, which are the forming emitters, choose SiO ₂ / Ni.

The thickness of the film flat element set 2 · 10 ^-7 m

In the manufacture of a film flat element on a substrate, a high-temperature oxidation of silicon is first used to form a compressed SiO ₂ forming layer 100 nm thick, onto which an unstressed 150 nm thick Ni layer is applied.

Prior to the deposition of a graphene layer, layer patterns are formed lithographically defining the emitter contours in the form of an angle with a vertex oriented along the <110> direction. Lithographic windows defining the patterns of layers and defining the contours of the emitter, made in the form of slits-segments forming an angle with a vertex along the indicated direction, are made by reactive-ion etching using: for a nickel layer etching in a 30% aqueous solution of FeCl ₃ at a temperature of 30 ° FROM; for a SiO ₂ layer — reactive ion etching in CF ₄ + O ₂ .

The structure is placed in a quartz reactor to form a graphene layer on the non-etched portions of the nickel layer. After pumping the quartz reactor with a fore-vacuum pump, a mixture of argon and hydrogen is launched into it and the temperature is raised to 900 ° C, then a mixture of argon, methane and hydrogen in the proportions of 100: 30: 20 is passed for 3 minutes. Next, the reactor is cooled at a rate of 3 ° C / sec, which leads to the formation of a graphene layer on the surface of the nickel layer with a thickness of 3 or in separate sections of 4 monolayers. The number of monolayers is determined from the Raman spectra of the amplitude and width of the peaks 2D (2700 cm ^-1 ) and G (1580 cm ^-1 ).

The forming layer of SiO _{2 is} formed compressed relative to the substrate.

Film flat elements are separated from the substrate with their transformation into emitters with a given three-dimensional spatial configuration. When separating the film flat elements from the substrate and transforming them under the action of internal mechanical stresses into emitters that are precisely located above the substrate, the material of the element lying under the film flat element is removed, thereby ensuring the location of the emitters above the substrate. The separation of the film elements starts from the angle formed by the slits, and is carried out by selective etching of a silicon substrate using anisotropy of etching in an ammonia solution (NH ₄ OH: H ₂ O - 1: 5). Etching is carried out until the partial separation of the film flat elements and transforming them into emitters. The etching is stopped after reaching the specified bend of the film element when it is transformed into an emitter and the emitter is oriented in the horizontal direction (see Figure 4), in which the electrons are emitted in the horizontal direction.

Curved needle-shaped emitters made on a substrate, strictly spatially oriented above it, are interconnected by sections of layers grown on the substrate during the formation of film flat elements, which remain on it after partial separation of film flat elements from the substrate.

Example 6

On a Si substrate with an orientation of (100), film flat elements are made containing the forming and functional graphene layers. Flat film elements are formed on a substrate with a desired location over its area. Then the film flat elements are separated from the substrate and transform them into emitters with a given three-dimensional spatial configuration due to the action of mechanical internal stresses, which are introduced into the forming layers during the transformation of flat film elements into emitters. The material, the geometry of the film elements and the internal mechanical stresses are selected in the manufacture of the film elements, providing the possibility of their separation from communication with the substrate and transformation under the action of internal mechanical stresses into emitters, which are precisely located above the substrate and have a precisely defined spatial configuration and geometric dimensions.

When film flat elements containing a forming and functional graphene layers are formed on a substrate, all emitter structural layers are made, and, using planar technology, lithographs are used to form layer patterns defining the emitter contours, and the emitter contour is formed to ensure its partial separation from the substrate.

The required arrangement of film flat elements, regular in area of the substrate, is provided by planar technology - lithographically.

Polymer layers are used as forming layers, into which internal mechanical stresses are introduced during the transformation of flat film elements into emitters due to heat treatment carried out using temperatures and duration that cause deformation of the polymer material. During heat treatment, a temperature of 150 ° C is used, and the duration is selected based on the given spatial configuration of the emitters - vertical (see Figure 5), in which the electrons are emitted in the vertical direction. Duration is determined visually by choosing the moment in time that the emitters reach the vertical orientation.

Polymethylmethacrylate (PMMA) is chosen as the material of the forming polymer layers of emitters into which mechanical internal stresses are introduced during the transformation of flat film elements due to heat treatment.

The thickness of the film flat element set 6 · 10 ^-8 m

In the manufacture of a film flat element on a silicon substrate, it is first transferred and “glued” according to the known method (Hailiang Wang, Xinran Wang, Xiaolin Li, Hongjie Dai “Chemical Self-Assembly of Graphene Sheets”, Nano Res (2009) 2: 336-342) a layer of graphene freed from bond with the substrate, which is preliminarily grown on the nickel substrate and disconnected from it in a selective etchant — a 30% FeCl ₃ solution. Then, a 60-nm-thick PMMA layer is formed on the graphene layer by centrifuging liquid PMMA at 6000 rpm. Dry the PMMA layer at a temperature of 100 ° C.

Lithographically form layer patterns defining the contours of the emitter in the form of an angle with a vertex oriented along the <110> direction. Lithographic windows defining the patterns of the layers and defining the contours of the emitter, made in the form of slits, segments, forming an angle with the apex along the indicated direction, are made by nanostamp lithography along the PMMA layer. By means of the windows formed by the stamp in PMMA, they are etched into the PMMA and the graphene layer to the substrate by plasma-chemical etching in O ₂ .

Film flat elements are separated from the substrate with their transformation into emitters with a given three-dimensional spatial configuration. When separating the film flat elements from the substrate and transforming them under the action of internal mechanical stresses into emitters that are precisely located above the substrate, the material of the element lying under the film flat element is removed, thereby ensuring the location of the emitters above the substrate. The separation of the film elements starts from the angle formed by the slits, and is carried out by selective etching of the substrate using etching anisotropy in a solution of ammonia (NH ₄ OH: H ₂ O - 1: 5). Etching is carried out until the partial separation of the film flat elements and proceed to their further transformation into emitters. Since mechanical stresses are almost completely absent between the graphene and PMMA layers, the film elements freed from bond from the substrate remain in a planar state, that is, they do not accept a three-dimensional spatial configuration, located above the substrate. In this regard, after drying, heat treatment is carried out at a temperature of 150 ° C, under the influence of which the PMMA layer is seated, pulled into a “drop”, thus initiating the occurrence of internal mechanical stresses. Shrinking, the softened PMMA layer “pulls” a graphene layer behind itself, which leads to the bending of the film elements with their transformation into emitters with a given three-dimensional spatial configuration. When the vertical location of the graphene layer relative to the surface of the substrate is reached, the heat treatment is stopped and the PMMA polymer is cured.

Curved needle-shaped emitters made on a substrate, strictly spatially oriented above it, are interconnected by sections of layers grown on the substrate during the formation of film flat elements, which remain on it after partial separation of film flat elements from the substrate. The height of the emitters in the array is strictly 0.1 μm.

Example 7

On the substrate of highly oriented pyrolytic graphite, film flat elements are made containing the forming and functional graphene layers. Flat film elements are formed on a substrate with a desired location over its area. Then the film flat elements are separated from the substrate and transform them into emitters with a given three-dimensional spatial configuration due to the action of mechanical internal stresses, which are introduced into the forming layers during separation and transformation of flat film elements into emitters. The material, the geometry of the film elements and the internal mechanical stresses are selected in the manufacture of the film elements, providing the possibility of their separation from communication with the substrate and transformation under the action of internal mechanical stresses into emitters, which are precisely located above the substrate and have a precisely defined spatial configuration and geometric dimensions.

When film flat elements containing a forming and functional graphene layers are formed on a substrate, all emitter structural layers are made, and, using planar technology, lithographs are used to form layer patterns defining the emitter contours, and the emitter contour is formed to ensure its partial separation from the substrate.

The required arrangement of film flat elements, regular in area of the substrate, is provided by planar technology - lithographically.

Polymer layers are used as forming layers, into which internal mechanical stresses are introduced during separation and transformation of flat film elements into emitters due to heat treatment carried out using temperatures and duration that cause deformation of the polymer material. During heat treatment, a temperature of 200 ° C is used, and the duration is selected based on the given spatial configuration of the emitters — vertical, at which the electrons are emitted in the vertical direction. Duration is determined visually by choosing the moment in time that the emitters reach the vertical orientation.

Polymethylmethacrylate (PMMA) is chosen as the material of the forming polymer layers of emitters into which mechanical internal stresses are introduced during separation and transformation of flat film elements due to heat treatment.

The thickness of the film flat element set 6 · 10 ^-8 m

In the manufacture of a film flat element on a substrate of highly oriented pyrolytic graphite, a 60-nm-thick PMMA layer is formed by centrifugation of liquid PMMA at 6000 rpm. Dry the PMMA layer at a temperature of 100 ° C. The near-surface layer of the substrate, on which the PMMA layer is formed, plays the role of a functional layer, in the future it is “torn” from the substrate.

Lithographically form patterns of layers defining the contours of the emitter in the form of an angle. Lithographic windows defining the patterns of layers and defining the contours of the emitter, made in the form of slits, segments, forming an angle, are made by nanostamp lithography on a PMMA layer. Using the windows formed by stamping in PMMA, PMMA and graphite substrates are etched into them to a depth of 3 monatomic layers by plasma-chemical etching in O ₂ .

Film flat elements are separated from the substrate with their transformation into emitters with a given three-dimensional spatial configuration. When separating the film flat elements from the substrate and transforming them under the action of internal mechanical stresses into emitters that are precisely located above the substrate, the material of the element lying under the film flat element is removed by “tearing off”, thereby ensuring the emitters are located above the substrate. The separation of the film elements begins from the angle formed by the slits-segments, and is carried out, as described above in this example implementation, by heat treatment carried out using temperatures and duration that cause deformation of the polymeric material PMMA, at a temperature of 200 ° C and duration until the vertical orientation.

Under the influence of temperature, the PMMA layer is seated, pulled together into a “drop”, thus initiating the appearance of internal mechanical stresses. Shrinking, the layer of softened PMMA “pulls” a graphene layer behind itself, which leads to separation by “tearing” from the substrate, bending of the film elements with their transformation into emitters with a given three-dimensional spatial configuration. When the vertical location of the graphene layer relative to the surface of the substrate is reached, the heat treatment is stopped and the PMMA polymer is cured.

Curved needle-shaped emitters made on a substrate, strictly spatially oriented above it, are interconnected by sections of layers grown on the substrate during the formation of film flat elements, which remain on it after partial separation of film flat elements from the substrate.

Claims (16)

1. The method of forming graphene field emitters, characterized in that the manufacture of film flat elements containing the forming and functional graphene layers, while flat film elements are formed on the substrate with the desired location along its area, then the film flat elements are separated from the substrate and transform them into emitters with a given three-dimensional spatial configuration due to the action of mechanical internal stresses, which are introduced into the forming layers or in the manufacture of film x flat elements, either during transformation, or during separation and transformation of flat elements into emitters, and the material, the geometry of the film elements and internal mechanical stresses are selected in the manufacture of film elements providing their separation from communication with the substrate and transformation under the influence of internal mechanical stresses into emitters located precisely above the substrate and having a precisely defined spatial configuration and geometric dimensions. 2. The method according to claim 1, characterized in that when forming flat film elements on the substrate containing the forming and functional graphene layers, all the structural layers of the emitter are fabricated, while using planar technology, lithographic patterns of the layers defining the contours of the emitter are formed, moreover, the emitter circuit form providing for its partial separation from the substrate. 3. The method according to claim 1, characterized in that as the forming layers use solid-state layers, which introduce internal mechanical stresses in the manufacture of film flat elements due to the difference in the constant crystal lattices of materials of the solid-state layers, or polymer layers into which the internal mechanical stresses during separation and transformation or transformation of flat film elements into emitters due to heat treatment carried out using temperatures and duration that cause de formation of polymer material. 4. The method according to claim 3, characterized in that during heat treatments use temperatures from 150 to 200 ° C, and the duration is selected based on the given spatial configuration of the emitters. 5. The method according to claim 1, characterized in that the required location of the flat film elements, regular in area of the substrate, is provided by planar technology lithographically. 6. The method according to claim 1, characterized in that highly oriented pyrolytic graphite or semiconductor material A ₃ B ₅ —GaAs, or semiconductor material of group IV of the D.I. Mendeleev table — Si — are selected as the substrate material. 7. The method according to claim 3, characterized in that SiGe / Si, or InGaAs / GaAs, or SiO ₂ / Ni, or SiGe / Si / SiO ₂ / Ni is selected as the material of the forming solid-state mechanically stressed emitter layers, and as the material of the forming polymer layers of the emitters, into which mechanical internal stresses are introduced during transformation or during separation and transformation of flat film elements into emitters due to heat treatment, choose polymethyl methacrylate. 8. The method according to claim 1, characterized in that as a functional graphene layer using a surface layer of a substrate of highly oriented pyrolytic graphite, or as a functional graphene layer using a layer of graphene grown on a donor substrate and transferred to the forming layers previously formed on GaAs or Si substrate, or as a functional graphene layer, a graphene layer grown directly on the forming layers previously formed on the substrate is used. ke GaAs or Si. 9. The method according to claim 6, characterized in that as a functional graphene layer using a surface layer of a substrate of highly oriented pyrolytic graphite, or as a functional graphene layer using a layer of graphene grown on a donor substrate and transferred to the forming layers previously formed on GaAs or Si substrate, or as a functional graphene layer, a graphene layer grown directly on the forming layers previously formed on the substrate is used. ke GaAs or Si. 10. The method according to claim 1, characterized in that the thickness of the film flat element set from 10 ^-8 to 10 ^-7 m 11. The method according to claim 1 or 2, characterized in that during the subsequent separation of the film flat elements from the substrate or during the subsequent separation of the film flat elements from the substrate and their transformation under the influence of internal mechanical stresses into emitters, located precisely over the substrate, the material of the element is removed lying under the film flat element, thereby providing an arrangement of emitters above the substrate. 12. The method according to claim 1, characterized in that the sacrificial layer is pre-grown on the substrate, the separation of the film flat elements is carried out by selective lateral etching of the sacrificial layer. 13. The method according to claim 1, characterized in that the separation of the film flat elements is carried out by selective etching of the substrate using anisotropy of etching. 14. The method according to p. 12, characterized in that AlAs is used as the material of the sacrificial layer. 15. The method according to p. 12, characterized in that in the sacrificial layer to enable lateral selective etching form lithographically window depth to the substrate. 16. The method according to claim 1, or 8, or 9, characterized in that in the manufacture of film flat elements in which a surface layer of a substrate of highly oriented pyrolytic graphite is used as a functional graphene layer, the substrate is etched to the depth of several atomic layers.

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