RU2676801C1 - Method of obtaining lateral nanostructures - Google Patents

Abstract

FIELD: nanotechnologies.SUBSTANCE: method of obtaining lateral nanostructures, in which the modulation of the composition of the nanostructure or heterostructure in the lateral direction is carried out without the use of nanolithography technique due to the peculiarities of the layer-by-layer growth mode of Frank-van der Merwe, in which, with the growth of a separate monolayer, tangential motion of the boundaries of islands, starting from defects inherited from layer to layer, different, alternating designs of nanostructures, materials. Inherited from a monolayer to a monolayer, crystal structure defects or artificially created nuclei determine the frequency of individual nanostructures grown by this method. Method distinguishes three modes in the growth mode of Frank-van der Merwe: 1) the radial motion of the island boundary (similar to the Volmer-Weber growth mode on the surface); 2) parallel displacement of the boundary (similar to the layered mode); 3) a point growth of the boundary only due to the capture of the adsorbed particle by a bend of a step.EFFECT: in the case of the implementation of the latter mode, it is possible to obtain lateral nanostructures that do not include the nucleus region associated with the inherited defect.1 cl

Description

3.2.4.1. The technical field to which the invention relates.

The invention relates to the field of application of nano-technology for producing specific nano-structures used in various fields of technology, including for the purpose of manipulating individual molecules and obtaining new nanostructures.

Classes of invention:

B82Y30 / 00 Nanotechnology

B82 B 1/00 Nano-structures obtained by manipulating individual atoms or molecules, or a limited set of atoms or molecules, as discrete objects

B82B 3/00 Production or processing of nano-structures by manipulating individual atoms or molecules, or a limited set of atoms or molecules, as discrete objects

3.2.4.2. The level of technology.

In fact, the first devices that can be classified as nanostructures are interference optical and X-ray mirrors, in which thin layers of materials with different refractive indices of light or different electron density alternate. Later, in similar layered systems, but with layer thicknesses of the order of several tens of atomic monolayers of magnetic and non-magnetic conductors, effects of giant magnetoresistance, tunnel magnetoresistance, spin valve, return superconductivity, etc., which are determined by the geometric parameters (subatomic layer thickness) are determined by materials included in the layered nanostructure. In the future, with the development of electronic lithography to subatomic resolution, it became possible to vary the sizes of the created devices in the plane of the layers — to obtain the so-called lateral nanostructures. Electronic lithography is a rather complicated technique using resistes, etching ... and its resolution is limited by the size of the electron or ion beam and the scattering of these particles in a resist. Also known is a method of producing nanostructures by mechanical action of the tip of a cantilever of an atomic force microscope directly on the formed layer or resist covering it. The present invention proposes another method for producing modulated, ideally, in three spatial directions, nanostructures. The level of technology of the invention should include information on the laws and mechanisms of heteroepitaxial growth of crystals and crystalline layers, methods for producing nanostructures, which also include methods for preparing the surfaces of substrates, methods, devices, and devices used in these processes. Basically, all of the above relates to the use of technology using molecular flows of deposited materials in vacuum, i.e. when the mean free path of the molecules of the applied materials is comparable to the size of the volume in which the operations are performed. However, in many cases, all this can be attributed to the processes of obtaining nanostructures by epitaxial growth in the gas or liquid phase, for example, using the methods of gas transport reactions or electroplating.

barrier) с «рябью» на дне, а в случае ковалентной связи этот рельеф может иметь вид отдельных близко расположенных достаточно глубоких потенциальных ям на фоне небольшого общего понижения потенциала притяжения. Более выигрышным оказывается положение у подножия атомной ступеньки (см. позицию «С» на фиг. 1). Еще более выигрышным в энергетическом отношении является положение в углу растущего монослоя (см. позицию «D» на фиг. 1), в изгибе ступени. Эти различия оказываются важными при дальнейшей эволюции структуры растущего слоя, первоначально определяемой свойствами подложки и условиями осаждения, именно: температурой подложки, шероховатостью ее поверхности, характером и плотностью дислокаций; энергией, плотностью и направлением потока конденсируемых молекул, их зарядом, присутствием остаточных (сопутствующих веществ) газов, излучением. Для ряда практических применений настоящего изобретения оказывается важным, что существуют механизмы самоорганизации скоплений молекул, адсорбированных идеальной поверхностью. Эти механизмы могут быть реализованы при определенных подобранных условиях. Так, в двухфазных системах с эффективным притяжением между фазами и эффективным отталкиванием внутри подвижной фазы возможна реализация механизма самоорганизации, аналогичного механизму образования двумерного вигнеровского кристалла [20] или пылевых кристаллов в плазме [21]. Аналогом таких конкурирующих взаимодействий, приводящих к возникновению на бездефектной поверхности подложки периодических структур с определенной симметрией и постоянной решетки, являются взаимодействия, приводящие к эффекту смачивания и напряжениям вследствие рассогласования решеток подложки и растущего эпитаксиального слоя.In general terms, the recognized scheme [1-18] for the deposition (condensation) of a molecular (atomic) beam (vapor) and the growth of an epitaxial layer on a crystalline (amorphous or textured) substrate is as follows. A condensing molecule (molecular ion, atom, particle of substance), before collision with the substrate, depending on the deposition method, has a certain kinetic energy. So, for example, in the case of the thermal evaporation method, this energy approximately corresponds to the temperature of the crucible. And in the case of magnetron radiofrequency sputtering, it can have energy comparable to the energy of the bombarding ions of the working gas and, in principle, also lead to the removal of the deposited molecules from the substrate. After adsorption on a substrate, this energy is given to the substrate and two-dimensional gas of adsorbed molecules during the relaxation time, which during this relaxation time are captured in more stable positions within the space of the order of the diffusion length. The stability of the position is determined by the number of molecules (respectively, energy gain) with which the adsorbed molecule (particle of the substance) forms a bond. Therefore, the position of the adsorbed molecule on a smooth surface (see positions "A, B" in Fig. 1) is the least advantageous and most uncertain (the reason for the formation of a two-dimensional gas). At the same time, the depth of the potential relief for adsorbed particles on an atomically smooth surface depends on the nature and direction of the bond, which ensures its retention on the surface. So in the case of a metal bond, this relief may have the form of a kind of deep “trough” (limited by the Ehrlich-Schwebel barrier;

barrier) with “ripples” at the bottom, and in the case of a covalent bond, this relief may take the form of separate closely spaced sufficiently deep potential wells against a background of a slight general decrease in the attraction potential. The position at the foot of the atomic step is more advantageous (see position “C” in Fig. 1). Even more energetically advantageous is the position in the corner of the growing monolayer (see position “D” in Fig. 1), in the bend of the step. These differences turn out to be important in the further evolution of the structure of the growing layer, initially determined by the properties of the substrate and the deposition conditions, namely: the temperature of the substrate, the roughness of its surface, the nature and density of dislocations; energy, density and direction of flow of condensed molecules, their charge, the presence of residual (related substances) gases, radiation. For a number of practical applications of the present invention, it is important that there are mechanisms of self-organization of clusters of molecules adsorbed on an ideal surface. These mechanisms can be implemented under certain selected conditions. Thus, in two-phase systems with effective attraction between phases and effective repulsion inside the mobile phase, a self-organization mechanism is possible that is similar to the formation of a two-dimensional Wigner crystal [20] or dust crystals in a plasma [21]. An analogue of such competing interactions leading to the appearance of periodic structures with a certain symmetry and lattice constant on a defect-free surface of the substrate are interactions leading to the wetting effect and stresses due to the mismatch between the substrate lattices and the growing epitaxial layer.

There are three main mechanisms of epitaxial growth, (see figures 1, 2), which are realized depending on the ratio of the kinetic energy of the adsorbed particles, the height of the diffusion barrier, the Ehrlich-Schwebel barrier, the depths of potential wells in the growing stage and its bend, and the particle flux density, the nature of their interaction with the growing layer and substrate.

координационным числом. При этом механизме процесс роста пленки состоит из следующих стадий: 1 адсорбция частиц первичной фазы на поверхности подложки и растущего слоя (позиции обозначенный как «А»; 2. Поверхностная диффузия адатомов к атомной ступени удержание их на ней (позиции «В»); Данное движение осуществляется как по верхнему монослою, над ступенью, так и нижнему монослою под ступенью. 3. Движение атомов вдоль ступени из позиций «В» и закрепление их в месте ее излома в позиции «С». Как можно сделать вывод из характера наблюдаемых и приводимых на стр. 10-12 в [19] монослойных структур (лучевые структуры островков, сплошные простые формы), их описанию, а также исходя из смысла градации потенциальных ям для адсорбируемых частиц и проистекающего из характера градации их диффузии (см. фигуру 1) послойная ростовая эпитаксиальная мода Франка-ван-дер-Мерве также имеет три под-моды (аналогично рассматриваемым модам I, II, III): 1. лучевое движение границы островка (аналогичное ростовой моде Вольмера-Вебера на поверхности); 2. параллельное смещение границы (аналогичное послойной моде); 3. точечный рост границы только за счет захвата адсорбируемой частицы изгибом ступени, (см. фигуру 8с). В последнем случае граница растущего слоя движется, в конечном счете, благодаря перемещению только одного изгиба ступени и монослой формируется аналогично растровому рисунку.I The layered mechanism of the Frank van der Merve is realized in the case of high mobility of adatoms on the perfect surface of the substrate and a significant increase in the binding energy of adatoms in positions with

coordination number. With this mechanism, the film growth process consists of the following stages: 1 adsorption of particles of the primary phase on the surface of the substrate and the growing layer (positions designated as “A”; 2. Surface diffusion of adatoms to the atomic stage, their retention on it (position “B”); This the motion is carried out both on the upper monolayer, above the step, and the lower monolayer under the step 3. The movement of atoms along the step from positions “B” and their fixing in the place of its kink in position “C.” How can we conclude from the nature of the observed and given on pages 10-12 of [19] mon layered structures (ray structures of islands, continuous simple forms), their description, and also based on the meaning of the gradation of potential wells for adsorbed particles and the diffusion resulting from the nature of the gradation (see figure 1), the layered growth epitaxial mode of the Frank van der Merwe also has three sub-modes (similar to the modes I, II, III under consideration): 1. radial motion of the island boundary (similar to the Volmer-Weber growth mode on the surface); 2. parallel displacement of the boundary (similar to layer-by-layer mode); 3. the point growth of the boundary only due to the capture of the adsorbed particle by the bend of the step, (see figure 8c). In the latter case, the boundary of the growing layer moves, ultimately, due to the movement of only one bend of the step and the monolayer is formed similarly to the raster pattern.

II. The embryonic growth mechanism of Volmer-Weber (Volmer-Weber) is realized on atomically smooth close-packed faces of a perfect crystal, which are the faces with small Miller indices. The growth of films in this mechanism occurs through the initial formation of two-dimensional or three-dimensional nuclei, which subsequently grow into a continuous film on the surface of the substrate. However, the probability of nucleation becomes noticeable only with significant supersaturations of several tens of percent. The formation, growth, and fusion of nuclei are based on the processes of mass transfer of a substance to a substrate, adsorption of its particles on the surface of a substrate, and surface diffusion of adsorbed particles. The relaxation time of changes between the particles physically adsorbed on the surface of the substrate and the particles located in its vicinity is microseconds. Therefore, the growth of nanostructures, on the one hand, is controlled by the processes of mass transfer and surface diffusion, or, on the other hand, to control it requires actions that have a shorter rise and fall time constant. For the Volmer-Weber germinal mechanism, the following sequence of film growth stages is called. 1. Adatoms having a surface concentration of N _a , interacting with each other according to a certain scenario, form critical nuclei with formation energy ΔG _cr and concentration N _cr = N _a ⋅exp (-ΔG _cr / kT). 2. Critical nuclei, due to the adatoms diffusing to them, turn into islands, growing in crystallographic directions with more free migration of adatoms and lower threshold energy for the formation of oriented nuclei. At the same time, it should be noted that the spontaneous formation of a screw dislocation provides faster growth of the island in which it was formed. 3. When the islands grow, they merge and a network of the germinal phase forms with voids bounded by crystallographic faces. 4. The final stage of growth of the primary layer ensures the filling of the voids of the island network and the formation of a continuous layer containing a certain fraction of misoriented grains, twinning boundaries, and dislocations.

During crystallization from the vapor-gas phase, the structural order is ensured by the mobility of adatoms on the substrate and, depending on the orienting properties of the substrate, either single-crystal epitaxial films or polycrystalline ones grow. When the mobility of adatoms decreases so much that the atoms condense directly at the point of their contact with the substrate, fine-grained polycrystalline or amorphous films are formed. This occurs either at low temperature or with a large number of exciting centers on the surface of the substrate.

Along with the usual Volmer-Weber mechanism with vapor condensation - crystal, in certain cases there is a condensation mechanism with an intermediate liquid phase. This mechanism works at high substrate temperatures T> 2 / 3T _m , where T _m is the melting temperature of the bulk substance, and is associated with a decrease in the melting temperature of small nuclei, an increase in the surface tension forces and a significant heat of condensation.

III. The mechanism, which is to some extent a combination of the above mechanisms, but which has its own importance in obtaining nanostructures, is the Stranski-Krastanov mechanism. In this mechanism, the epitaxial layer grows to a certain critical thickness layer by layer, resembling the Frank-van der Merwe growth mode, and at thicknesses greater than critical, the growth is mainly due to regular-shaped nano-islands, which also form fairly regular structures.

The listed mechanisms of epitaxial growth are used in the preparation of layered (frontal) heterostructures and nanostructures. In combination with electron or ion beam lithography methods, lateral nanostructures are obtained. In the process of obtaining certain nanostructures, alternating growth mechanisms are used. An example of the latter are nanostructures with quantum dots, i.e. layered growth mechanisms and Stransky-Krastanov alternate. However, in this case as well, quantum dot nanostructures are essentially layered nanostructures and lithography methods are used to obtain lateral nanostructures in this way.

The closest analogue.

The closest analogue of the proposed method is the method described in [21] and “A method for manufacturing quantum structures: quantum dots, wires, elements of quantum devices” protected by RF patent No.RU 2278815 (1997) (http://www.findpatent.ru/ patent / 227 / 2278815.html) Authors of the invention: Prince Alexander Viktorovich (RU), Prince Victor Yakovlevich (RU), Owner of patent RU 2278815: Prince Alexander Viktorovich (RU).

An earlier analogue of the invention is the US patent Petroff P. et al. "Quantum dot fabrication process using strained epitaxial growth", US patent No. 5614435, 1997). Regarding this invention, the authors of patent RU 2278815 (1997) indicate that "Petroff et al. Described a method for producing quantum dots that does not require the use of lithography."

The authors indicate that “The most common, perfect and technologically advanced are methods based on the self-formation of quantum dots in the process of heteroepitaxial film growth with a large mismatch between the constant lattices. At a certain critical thickness of the grown compressed film, there is a transition from two-dimensional to three-dimensional growth (Stransky-Krastanov process). ”“ The method involves the deposition of a material having an atomic lattice constant different from the lattice constant of the substrate. Under the influence of internal stresses caused by the mismatch of the atomic lattice constants, self-formation of quantum dots from the deposited material occurs. During the deposition process, the surface is observed by diffraction of the reflected high-energy electrons, which allows to stop the growth when the desired number of quantum dots is formed. Deposition can be carried out both by molecular epitaxy and other deposition methods, such as gas-phase epitaxy, metal-organic chemical deposition, etc. " “The disadvantages of the methods are that the quantum dots obtained by this method are formed mainly independently of each other and therefore are located irregularly in a random place on the substrate and always vary to some extent in size. It is necessary to increase their uniformity, orderliness and surface concentration. In addition, the energy barrier at such quantum dots is small, and low temperatures are necessary for the manifestation of dimensional quantization.

The technical result of the invention is the creation of a more efficient manufacturing technology of quantum objects; expanding the range of materials used; improving the characteristics of the resulting elements - an increase in the quantum barrier; the ability to simultaneously control the mechanical and electrical properties of objects; the ability to accurately position individual and arrays of quantum dots and elements of quantum devices; the ability to accurately set the size of quantum objects.

The technical result is achieved by the fact that in the method of manufacturing quantum objects (dots, wires and elements of quantum devices), which includes growing a strained film from a material having a crystal lattice constant greater than the substrate material, the thickness of the strained film is less than critical and the film is grown pseudomorphic, and between the strained film and the substrate, a sacrificial layer is grown, which is then selectively removed under a predetermined region of the film, which frees part of the film from communication with the substrate, and this part is bulging or corrugating, as a result of which the voltage in the film changes, which in turn causes a shift in the bottom of the conduction band (the top of the valence band), which leads to the formation of a local potential well for carriers.

A strained film consists of several layers of different substances. A stressed film consists of a layer with a predominant location of charge carriers and a layer with practically no charge carriers. A multilayer structure of two or more stressed layers separated by sacrificial layers is used as a strained film, and then partial removal of the sacrificial layers is carried out. ”

Thus, it should be emphasized that the technical result of the claimed invention is also the creation of a simple and universal technology for manufacturing complex nano-objects without the use of lithography.

3.2.4.3. SUMMARY OF THE INVENTION

The essence of the invention, and with it the difference from analogues, formally consists of using the layer-by-layer growth regime of Frank-van der Merwe instead of the islet growth mode of Stransky-Krastanov with similar methods for controlling the growing epitaxial layer. However, the fundamental difference of the proposed method is the use of layer-by-layer growth to obtain a technical result of the fact of movement in the lateral direction of the boundaries of the layer growing in the Frank-van der Merwe mode. This point is noted in some sources, but the fact that under certain conditions it can be used to grow complex lateral nanostructures without the use of lithography is not indicated in these sources. To disclose the essence of the invention, we turn to figures 9 and 10. Figure 9 conditionally presents a substrate containing screw growth dislocations. It is known from the prior art that in the layer-by-layer Frank-van der Merwe growth mode (see also figure 4b), nucleation of growth islands occurs on defects of the substrate surface in the form of step bends, which, when the surface layer is completely built up, are located on the axis of the screw dislocation (see Figures 7, 8). Thus, the epitaxial monolayer growth pattern shown in FIG. 4b due to the transition of the bending steps of the growth screw dislocations to the next layer is repeated in subsequent layers. Obviously, in the layer-by-layer growth mode of the epitaxial film of material “A” (see Figure 10) on an ideal defect-free substrate, we can stop this growth at some stage, which we denote by the value (layer growth phase) θ _A1 and continue the growth of this layer in the same mode, slightly changing the process parameters, with material “B” up to the moment θ _B1 . After this, we continue the growth with the material “C” (etc.) until θ _C1 or again with the material “A” until the complete construction of the monolayer of these materials. Obviously, we will get some kind of “ornament”, determined by the difference in growth rates (speeds of movement of the boundaries of the monolayer) along different crystallographic directions. Now, if we repeat this process with the change of materials with the growth of the second (etc.) layer at the same moments (monolayer growth phases) θ _A1 = θ _A2 , θ _B1 = θ _B2 , θ _C1 = θ _C2 , then we also obtain some (let's say pseudo-ring) “ornament” from materials “A”, “B”, “C”. It should be emphasized here that from the point of view of energy gain due to epitaxial stresses, each material is more advantageously placed on a layer with the same material. However, it cannot be argued that during the growth of such layers in the subsequent layers, the ornament of the first layer will be preserved, as well as the points of origin of each ornament motif from monolayers of materials “A”, “B”, “C” ... Thus, it is not obvious to a specialist that from the fact of the tangential movement of the boundaries of monolayers growing in the Frank van der Merwe regime, the possibility of obtaining lateral nanostructures from various materials automatically follows. But it is obvious that in the case of spatial regularity (coherence) of the nucleation points of monolayer islands, complete transverse homogeneity and linearity of the fronts of the flows of materials “A”, “B”, “C”, the possibility of quick adjustment of the intensity of flows, strict determination of the capture of condensed particles of materials in place bending the steps of monolayers, varying the moments θ _An , θ _Bn , θ _Cn, it is possible to obtain the same (and not only ring) motifs of the ornament in all monolayers, as well as smoothly change them from layer to layer. Not circular, i.e. without the axis of dislocation, the motives of the “ornament” can be obtained by providing the conditions for the deposition of adatoms exclusively on one bend of the growth stage, and thereby rigorously determining the spiral growth of the monolayer around the axis of the screw dislocation in the field of its influence. In this case, a stronger synchronization of the moments θ _An , θ _Bn , θ _Cn will be required not only at the level of the monolayer growth phase, but also at the level of the step growth phase. Given that the diffusion of adatoms (particles) over the surface of the substrate and epitaxial layer occurs through potential wells of growth positions (see Figures 1, 2), in which they can linger and be in a state of vibrational movements, allowing the development of branches of undesirable growth (see figure 8c), to suppress this growth and accelerate diffusion at these positions, resonant pumping is used at the vibration frequency of adatoms (particles) in these positions.

By performing selective etching of any material, as planned by the geometry of the nanostructure, in this case, it would be possible to obtain nanostructures of any shape. In the case shown in figure 11, the material “A” can be platinum, the material “B” is copper or cobalt, the material “C” is magnesium oxide, aluminum oxide, or, for example, a water-soluble substrate material - sodium chloride. After completion of the growth processes, by removing a certain material by dissolution, we obtain a grid of elements of plasmonics devices, memory, or, as in the case shown in figure 11b, an element of a molecular sieve. An obstacle to obtaining an ideal network of such nanostructures is the destruction of spatial coherence (regularity) of both the location of the nuclei in the monolayers and the motion of the boundaries of the steps associated with these nuclei. In the claimed invention, these problems are solved, not counting the selection of materials, as follows.

1. To control the movement of borders in a growing monolayer, the following measures are applied.

a) Adjustable oblique incidence of particles in the flow of materials. In this case, the advantage in growth is obtained by the flow side.

b) Variation of the energy of the falling particles — an increase in energy leads to a higher effective temperature on the adsorbing surface and, accordingly, an increase in the path length and an increase in the probability of capture by the bend of the growing stage, rather than settling in a random place.

c) An increase in the mobility of adsorbed particles by means of laser irradiation at frequencies corresponding to their vibrations in traps on the surface of a growing monolayer, and by means of background bombardment by ions of light elements.

d) The nature of the motion of the boundaries is also determined by the choice of substrate material and their crystallographic orientation. Strip structures grow on substrates with official surfaces, while the presence of the hexagonal axis of the perpendicular surface, and even in the presence of helical growth dislocations of the substrate, facilitates the production of tubular nanostructures. It should be noted that the claimed invention in the latter case is realized in the absence of spatial coherence of the embryos in the first monolayer.

2. To ensure spatial coherence in the first monolayer, the following measures and effects are possible.

a) It is known that in two-component systems with repulsion between moving particles and their attraction to the continuum in which they are, especially in the two-dimensional case, these particles form a regular spatial lattice [20, 21]. It can be expected that in the presence of effective repulsion (for example, as surface tension forces pull apart particles from one another and collect others into lumps) between adsorbed foreign particles, they form a lattice whose parameters are not related to the crystal lattice parameters of the substrate. These particles can subsequently become nuclei of islands during epitaxial growth in the layered regime of Frank van der Merwe. Dislocations of the same sign possess the same mutual repulsion property, which under certain conditions can lead to the formation of regular structures from growth dislocations.

b) The primary network of islet nuclei can be deposited on a substrate using a molecular monolayer epitaxial mask. As a primary, easily removable mask, a monolayer of fullerene molecules (or other large molecules), epitaxially (or otherwise, depending on the task) grown on a substrate, can be used (see example in Fig. 6) Through triangular gaps between spherical fullerene molecules nuclei are sprayed onto the atomic material used in the formation of the nanostructure, which, in particular, can chemically bind to the substrate material. The gaps have a bore diameter of about 0.25 nM, which is comparable to the lattice constant of many transition metals, and a tetrahedral void with a side of about 0.65 nM. Taking into account that the “metallic” radius of an atom, for example, molybdenum is about 0.14 nM, a nucleus consisting of 30-35 atoms can be placed in this void, which, when deposited in the Volmer-Weber mode, can go beyond the monolayer of fullerene molecules. A monolayer of fullerene molecules, depending on the substrate, may have a second, third, fourth or sixth order axis of symmetry. Under the fullerene monolayer, an epitaxy-facilitating buffer layer, for example, molybdenum, can be deposited, or a buffer layer giving a different epitaxial ratio and the lattice constant of the receiving layer, as shown in Figure 5 c. Then, the fullerene molecules together with the material atoms associated with them are removed by heating the substrate with nuclei until the monolayer of fullerene molecules evaporates. The obtained network of nuclei with a lattice constant of about 1.4 nM (3.95 nm for the system shown in Figure 5) is used as the basis for obtaining a network of lateral nanostructures: In the layer-by-layer growth mode, the nuclei are grown to the required size, determined by the intensity of the electron diffraction pattern, then in this In the same mode, the gaps between the embryos with other material are filled and the process is repeated again with the first material.

c) The primary network of islet nuclei is formed by the deposition in the Volmer-Weber growth mode of material “A” onto a buffer monolayer with a modulated lattice constant, due to a mismatch in the lattice constants of the buffer layer and the substrate. An example of modulation of the lattice of a buffer layer can be the deposition of a KBr monolayer on a NaCl substrate (see [7, 8] and Figures 1, 2, 5). In this case, the material “A” will collect in places with the lowest epitaxial voltage and the resulting network of nanostructures will have a period of 3.95 nM. The use of other pairs of substrate materials and a buffer layer, of course, will give a different period of the grid of nanostructures. In this way, it is possible to grow, for example, magnetic filaments long enough for the magnetic elements to escape from the superparamagnetic state.

d) A network of nuclei is formed at the steps of misfit dislocations that arise due to the mismatch of the lattice constants of the substrate and the buffer layer, the material of which can be one of the materials used in the growth of lateral nanostructures by the claimed method. The larger the difference in lattice constants, the greater the density of dislocations on which nanostructures are attached and formed. Accordingly, in order to assess the moments of change in the feed materials and the sizes of the grown nanostructures, the question of the density and nature of the misfit dislocations arising in this material-substrate system should be investigated.

e) A network of nuclei of nanostructures is formed on growth dislocations of the substrate itself, which arise during the growth of a single crystal of the substrate, or are purposefully formed as a result of its special processing. In particular, dislocation mismatches with the right and left screw components are of interest. The density of growth dislocations, according to p. 11 in [18], can reach 10 ¹⁵ -10 ¹⁶ M ^-2 , which corresponds to the effective grid period of 10 nM nanostructures obtained on them and the corresponding information recording density in the case of growing magnetic nanostructures on them. To order the obtained lateral nanostructures obtained by the claimed method, substrates with vicinal surfaces of crystallographic planes with small Miller indices can be used.

The expected technical result of the invention is to obtain single lateral nanostructures and regular networks of such nanostructures with lateral sizes that are currently unavailable for lithography methods of the order of several nanometers. As indicated above, the possible recording density during the production of magnetic nanostructures on growth dislocations in the substrate in this way is of the order of 10 ¹⁵ Bit. In the case of the formation of magnetic memory elements on the modulated buffer layer KBr or under the epitaxial layer of fullerene, the recording density can be, respectively, 6⋅10 ¹⁶ and 4⋅10 ¹⁷ Bit.

With the same density, tips of autoemitters, membranes and molecular sieves, nano-accelerators of charged particles, plasmonics devices, single-electronics, spintronics, known semiconductor devices such as gates and transistors can be grown.

3.2.4.4. The list of figures, drawings and other materials.

barrier).Figure 1. The gradation of potential wells on the surface of the substrate for adsorbed particles of a substance. Ehrlich-Schwebel barrier. (

barrier).

Figure 2. The main types of growth modes with epitaxial growth.

Figure 3 Schematic diagram of the installation of molecular beam epitaxy with the control of the surface of the growing layer of the node according to the diffraction intensity of fast electrons.

Figure 4. A characteristic graph of changes in the intensity of diffraction reflections of fast electrons and the growth phase of the monolayer.

Figure 5. An example of lateral modulation of the constant lattice of the buffer layer during epitaxy of potassium bromide on sodium chloride.

Figure 6. The growth of a monolayer of fullerene C ₆₀ on a substrate of sodium chloride

Figure 7. The structure of penetrating screw and edge dislocations, the formation of mixed dislocations.

Figure 8. Examples of tangential displacement of steps during the growth of single crystals on screw dislocations.

Figure 9. Scheme of layer-by-layer growth of a single crystal on a substrate with randomly spaced penetrating screw growth dislocations.

Figure 10. Schematic diagram of the formation of a complex nanostructure on a helical growth dislocation.

Figure 11. Schematic diagram of the formation of the molecular sieve element on the modulated structure of the buffer layer.

10.7.4.4. Brief Description of the Drawings

barrier). Адсорбированные атомы или частицы на поверхности кристалла при физической адсорбции удерживаются на поверхности силами Ван-дер Вальса, которые создают на поверхности потенциальный рельеф, глубина которого зависит от числа соседей, с которыми взаимодействует частица. В этой модели адсорбированная частица (позиции А и В) удерживаясь на поверхности, относительно свободно может диффундировать вдоль нее до попадания в потенциальную яму, связанную со ступенью. Находясь в этой яме частица также относительно свободно может перемещаться вдоль ступени (позиции типа С) до попадания в позицию D с более глубокой и более локализованной потенциальной ямой. Кроме того в зависимости от природы вещества выходу адсорбированной частицы с растущего слоя может препятствовать барьер Эрлиха-Швёбеля.Figure 1. The gradation of potential wells on the surface of the substrate for adsorbed particles of a substance. Ehrlich-Schwebel barrier. (

barrier). At physical adsorption, adsorbed atoms or particles on a crystal surface are held onto the surface by Van der Waals forces, which create a potential relief on the surface, the depth of which depends on the number of neighbors with which the particle interacts. In this model, an adsorbed particle (positions A and B) being held on the surface can relatively freely diffuse along it until it enters a potential well associated with the step. Being in this well, the particle can also move relatively freely along the step (type C position) until it reaches position D with a deeper and more localized potential well. In addition, depending on the nature of the substance, the exit of the adsorbed particle from the growing layer may be impeded by the Ehrlich-Schwebel barrier.

Figure 2. The main types of growth modes with epitaxial growth. The illustration is taken from [7]. Original: “Figure 1: Schematic representation of the three known film growth modes. The spheres can be either atoms or NPs. When NPs approach a substrate, either adsorption, desorption or diffusion occurs. Depending on the free energy contributions one finds Frank-van-der-Merwe (FvdM), Volmer-Weber (VW), or Stranski-Krastanov (SK) growth. ”Spheres are atoms or nanoparticles that are adsorbed or desorbed on the surface of a substrate or growing layer and which diffuse along these surfaces, lingering in shallow potential holes. At a low Ehrlich-Schwebel barrier or a sufficiently high temperature, particles adsorbed on a growing layer fall on the step of this layer and, again, with sufficient mobility of the particles along the step, migrate to its bend and settle in it. Particles adsorbed by a completed monolayer or surface of a substrate diffuse similarly to the step. In the case of low mobility of the adsorbed particles along the stage, there are many foci of growth of the stage. Thus, a layer-by-layer growth mode of the Franck van der Merwe, in which predominantly point growth or growth along the entire step can be realized, is realized. With a sufficiently high Ehrlich – Schwebel barrier, the Stransky – Krastanov layer-by-volume growth mode or the Volmer-Weber purely volume growth mode are realized

Figure 3. Schematic diagram of the molecular beam epitaxy unit with the control of the surface of the growing layer of the node by the intensity of diffraction of fast electrons. The figure explaining the principle of molecular beam epitaxy was taken from the Surface Physics course [19]. 9. Growth of Thin Films: Dr. Enrico Gnecco, Assistant NCCR Nanoscale Science of Basel University, https://nanolino.unibas.ch/pdf/surfacephysics/oberflaeche9.pdf

Figure 4. A characteristic graph of changes in the intensity of diffraction reflections of fast electrons and the growth phase of the monolayer. The figure is used in various sources and is taken from [19] here. It can also be seen from the figure that the fact of the nucleation of numerous islands in a layer-by-layer epitaxy regime is obvious and known.

Figure 5. An example of lateral modulation of the constant lattice of the buffer layer during epitaxy of potassium bromide on sodium chloride. The figure shows how the mismatch of the constant lattices of the substrate and the growing layer leads to regular deformation of this layer and the appearance of a superstructure of the layer with a large period of 3.95 nM instead of the initial 0.658 nM. Figure taken from [8] and [19]. This structure can serve as the basis for the production of membranes selectively retaining fullerene C ₆₀ molecules

Figure 6. The growth of a monolayer of fullerene C ₆₀ on a substrate of sodium chloride. The figure demonstrates the possibility of obtaining fullerene monolayers and the nontrivial epitaxial ratio of the C ₆₀ monolayer with the substrate. Figure taken from [8].

Figure 7. The structure of penetrating screw and edge dislocations, the formation of mixed dislocations. Legend: Screw - screw dislocation, Edge - edge dislocation, Mixed - mixed dislocation, b - Burgers vector. Figure taken from [18] p. 7 http://www.inorg.chem.msu.ru/pdf/Defects2.pdf

Figure 8. Implementation of growth modes. a) b) - Examples of the tangential displacement of steps during the growth of single crystals on screw dislocations. Figure taken from [18] p. 25. c) - three modes of the growth mode of the Frank van der Merwe platinum on platinum, realized at fairly close epitaxy temperatures of -300 K, 400 K, and 425 K. [18] p. 10-12

Figure 9. Scheme of layer-by-layer growth of a single crystal on a substrate with randomly spaced penetrating screw growth dislocations. Designations: Substrate - substrate. The dashed vertical lines show the axis of the screw dislocations of the substrate. Ellipsoids - denote repeating regions (fields) in each monolayer grown in the Franck van der Merwe mode, for the growth of which the corresponding dislocations were responsible.

Figure 10. Schematic diagram of the formation of a complex nanostructure on a single screw growth dislocation, a) Schedule of registration of the diffraction intensity of fast electrons (according to the type of figures 3 and 4). The graph shows sections A, B, C, during which materials “A”, “B”, “C” were fed into the growth zone. b) Formation of the distribution of materials A, B, C in two (in each) monolayer after its complete construction. The substrate material was taken as material C, c) Coaxial nanostructure obtained after removal of material C. In general, the sample is a network of such nanostructures, d) a legend indicating the designation of materials.

Figure 11. Schematic diagram of the formation of the molecular sieve element on a single screw growth dislocation or on a preformed nucleus on a modulated structure of the buffer layer (see Fig. 5 and 6 and the main test). During the growth of each layer, an expanding central zone of material “B” was formed around the embryo, then a ring of material “A” was formed and the layer was extruded to integrity by material “C” (in the description, this is the substrate material). In the final stage, material “C” was excluded and a thick membrane-bearing layer of material “A” was grown (in the description, platinum)

3.2.4.5. Information confirming the possibility of carrying out the invention.

The existence of the devices mentioned in the section "Background" for epitaxial film growth on single crystal substrates and control this growth is confirmed by the sources listed in the list of literature and, in particular, the description of the prototypes of the invention. In these sources, as educational material, information is given on the possibility of realizing a layered, in monolayer of atoms and particles of substance, epitaxial growth mode of Frank van der Merwe, along with other growth modes of Volmer-Weber and Stransky-Krastanov. The last named mode is used to obtain lateral nanostructures (semiconductor quantum dots) without using the technique of nanolithography.

The listed sources contain information about the tangential movement of the boundaries of the islands of monolayers during layer-by-layer epitaxial growth in the Franck van der Merwe mode, on which the inventive method for producing lateral nanostructures is based. This fact about the movement of boundaries naturally follows from the meaning of this layered epitaxial growth mode.

The listed sources also contain information on piercing dislocations, the role of screw dislocations in the growth of bulk single crystals, in particular, used for the preparation of substrates on which epitaxial layers of other materials are then grown. They also contain information about the main essence of the mechanism of the Frank van der Merwe growth mode — the expansion of the steps of monolayers — spontaneously nucleated, artificially created or existing from the sense of crystal structure defects (screw dislocations).

However, in all known sources there is no indication that certain defects on which the nucleation of a new epitaxial growing layer occurs are retained in the grown layer and transferred to a new layer. The same sources do not contain information on the use of the layered growth mode of Frank van der Merwe to obtain lateral nanostructures without the use of nanolithography, realizing the tangential movement of the boundaries of islands starting from defects inherited from layer to layer by sequential growth of various materials .

Bibliography,

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Claims (10)

A method for producing lateral nanostructures, including spatial modulation of the composition of nanostructures in the lateral direction due to temporal modulation during their epitaxial growth of the composition of the material flow supplied to the growing layer, characterized in that - temporary modulation of the composition of the material flow supplied to the growing layer is based on the design of the grown nanostructure, in accordance with the growth phase of each layer, which is also controlled by electron diffraction on this layer; - the growth of the lateral nanostructure is carried out in the growth mode of the Frank van der Merwe mode, supported, if necessary, by laser irradiation at the frequency of the vibrational mode of the adatoms and background bombardment by ions of light elements, the growth modes of Volmer-Weber and Stransky-Krastanov are used in preparatory operations; - to specify the primary spatial structure in the lateral direction, structured single-crystal substrates of a given orientation (vicinal, hexagonal, etc.) with a given character and density of growth dislocations can be used; - to set the primary spatial structure in the lateral direction, the effects of self-organization of clusters on the substrate surface can be used as multicomponent systems with repulsion between particles of the same kind and attraction between components; - to specify the primary spatial structure in the lateral direction, the effects of lateral modulation of the lattice size of the buffer layer can be used when the structures of the layer and substrate are mismatched; - to specify the primary spatial structure in the lateral direction, epitaxial molecular masks from large molecules or nanostructures such as fullerenes can be used, self-removing after creating a grid of clusters from the primary material; - during the in-phase change of the supplied material in order to keep the technological parameters within the growth mode used for this material, additional radiation heating of the deposited layer, its directed bombardment by light ions, variation of the energy of the deposited molecules or ions can be used; - to control the growth of islands in the lateral direction, the phase of the deposition of the deposited material, the energy and direction of incidence of the deposited particles or ions on the substrate, as well as the direction of incidence, the energy and intensity of the background bombardment by light ions, can vary; - to obtain lattices from specific nanostructures, namely: memory cells; catalysts with a special surface; molecular sieves and membranes; auto cathodes; ion sources and structural elements of ion engines and nanocannons; nano-devices of plasmonics, photonics, spintronics and electronics; technologically sacrificial materials are used.

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