Seed layer, heterogeneous structure including the seed layer, and method for forming a material layer using the seed layer

Abstract

A seed layer (102) for inducing nucleation to form a material layer (106) is described. In one embodiment, the seed layer (102) includes a layer of a two-dimensional (2D) monolayer amorphous material having a disordered atomic structure suitable for generating localized electronic states to form potential wells for binding adatoms to the surface of the seed layer (102) via van der Waals (vdW) interactions to form the material layer, wherein the potential wells each have a potential energy greater in magnitude than the surrounding thermal energy to trap adatoms on the surface of the seed layer. Also described are embodiments of a method for forming the seed layer, a heterostructure 100 including the seed layer (102), a method (300) for forming the heterostructure including the seed layer, a device including the heterostructure, and a method for enhancing vdW interactions between adatoms and the surface of the seed layer. In a specific embodiment, the layer of the 2D monolayer amorphous material is a 2D monolayer amorphous carbon.

Description

Technical Field

[0001] The present disclosure relates to a seed layer, a heterostructure including the seed layer, and a method of forming a material layer using the seed layer. Background Art

[0002] The integration of heterogeneous materials is an important aspect of manufacturing high-performance semiconductor devices. For example, high-speed and efficient optoelectronic devices such as light-emitting diodes, infrared (IR) sensors, photodetectors and solar cells generally involve the need to integrate III-V (GaAs, GaN, InP, etc.) and II-VI (CdTe, CdS, ZnS, oxides, etc.) semiconductors with silicon (Si) microelectronics. The advantages of such integration are attributed to the excellent optoelectronic properties achieved by III-V or II-VI materials, as well as the compatibility and economic feasibility of Si with complementary metal oxide semiconductor (CMOS) technology.

[0003] The conventional technique for forming such multilayer heterostructures is epitaxial growth, in which epitaxial layers of material grown on a substrate are covalently bonded to the underlying substrate material. However, stringent requirements need to be met to achieve reasonable quality for such multilayer heterostructures, which has limitations on their general applicability. For example, direct heteroepitaxial growth of III-V or II-VI materials on Si using conventional epitaxial growth methods is generally not possible due to thermal expansion, polarity, and lattice mismatch between III-V or II-VI materials and Si.

[0004] One way to overcome this is by using van der Waals epitaxy (vdWE) technology. Van der Waals epitaxy (vdWE) technology is based on non-covalent interactions between adatoms and substrate surfaces. The non-covalent interactions relax the lattice alignment requirements and allow materials with relatively large mismatches to grow on each other. Due to its compatibility with the growth of two-dimensional (2D) materials, vdWE technology has become an interesting material growth method for promoting semiconductor device manufacturing in recent years. Unfortunately, crystalline 2D materials typically lack dangling bonds on their surfaces and therefore provide very low surface energy and adsorption energy for adatoms during subsequent epitaxial growth. This makes it challenging to grow heterostructures using vdWE technology for achieving uniform, strain-free films, which often result in island growth, low growth rate and defective films for subsequent epitaxial growth. This inadvertently affects the device performance of the resulting device. Due to the weak vdW interaction used in the vdWE technology, it is even more challenging to integrate three-dimensional (3D) materials on 2D materials. This weak vdW interaction causes the surface of 2D materials to be very poorly wetted by typical 3D materials, resulting in the formation of inhomogeneous, strained, and clustered 3D material films rather than uniform, planar films.

[0005] It is therefore desirable to provide a seed layer that solves the aforementioned problems and / or provides a useful alternative, a heterostructure comprising the seed layer, and a method for forming a material layer using the seed layer. Further, other desired features and characteristics will become apparent from the subsequent detailed description and the appended claims considered in conjunction with the accompanying drawings and the background technology of the present disclosure. Summary of the invention

[0006] Aspects of the present application relate to a seed layer, a method of forming the seed layer, a heterostructure including the seed layer, a device including the heterostructure, a method of forming a material layer using the seed layer, and a method of enhancing the van der Waals (vdW) interaction between adsorbed atoms and the surface of the seed layer.

[0007] According to a first aspect, a seed layer for inducing nucleation to form a material layer is provided. The seed layer comprises a layer of a two-dimensional (2D) monolayer amorphous material having a disordered atomic structure suitable for generating (multiple) localized electronic states to form (multiple) potential wells for binding adatoms to the surface of the seed layer via van der Waals (vdW) interactions to form the material layer, wherein the (multiple) potential wells each have a potential energy greater in magnitude than the surrounding thermal energy to trap adatoms on the surface of the seed layer.

[0008] By using a seed layer comprising a layer of a two-dimensional (2D) monolayer amorphous material having a disordered atomic structure, a plurality of localized electronic states are generated by the disordered atomic structure to form a plurality of potential wells that act as high energy sites for adsorption of adatoms during the growth of the material layer via vdW interactions. This results in a stronger interaction between adatoms and the surface of the seed layer and a higher nucleation density of adatoms on the surface of the seed layer (e.g., when compared to conventional vdW epitaxy), which together act to enhance the wettability of adatoms on the surface of the seed layer to achieve uniform planar material layer growth. In addition, the disordered atomic structure of the seed layer can also be adjusted from a fully amorphous phase to a nanocrystalline phase to regulate the interaction between the underlying substrate and the material layer, thereby providing a useful way to remotely control the growth of the material layer. Further, since the growth of the material layer is derived from the vdW interaction between adatoms and the seed layer, the seed layer acts as a universal seed layer for allowing the growth of any material layer on any substrate. Still further, stronger vdW interactions between the surface of the seed layer and the material layer allow the grown material layer to detach from the underlying substrate to produce a free-standing film, which can be advantageous in terms of the design of heterostructure electronic devices.

[0009] The layer of 2D single layer amorphous material may include a 2D single layer amorphous carbon.

[0010] The seed layer may have an optical transparency greater than 98% at a light wavelength of 550 nm to 800 nm.

[0011] The seed layer may be thermally stable from room temperature to 700°C, from room temperature to 600°C, from room temperature to 500°C, from room temperature to 400°C, from room temperature to 300°C, from room temperature to 200°C, from room temperature to 100°C, or at a temperature of 600°C-700°C, 500°C-700°C, 400°C-700°C, 300°C-700°C, 200°C-700°C, 100°C-700°C, 20°C-700°C, or at 700°C.

[0012] The seed layer may include one or more further layers of the 2D single layer amorphous material deposited on the layer of the 2D single layer amorphous material to form the seed layer of a multi-layer structure.

[0013] According to a second aspect, a method for forming a seed layer is provided, wherein the seed layer includes a layer of a two-dimensional (2D) single-layer amorphous material having the following disordered atomic structure: it is suitable for generating multiple localized electronic states to form multiple potential wells for binding adsorbed atoms to the surface of the seed layer via van der Waals (vdW) interactions to form the material layer, wherein each of the multiple potential wells has the following potential energy: it is larger in size than the surrounding thermal energy to trap adsorbed atoms on the surface of the seed layer, and the method includes: growing the seed layer on a substrate using laser assisted chemical vapor deposition (LCVD).

[0014] By utilizing a photolytic decomposition process, LCVD enables the non-catalytic growth of the seed layer at low temperatures directly on a wide variety of substrates (metals, semiconductors, insulators, glasses, and polymers). Photolytic decomposition refers to the use of one or more photons to induce a chemical reaction of a molecule to decompose the molecule into simpler particles. This provides many advantages. First, the use of laser-assisted CVD allows the seed layer to be grown directly on the substrate of interest and therefore bypasses the time-consuming transfer method that is usually practiced when the seed layer or the material of interest can only be grown on a specific base substrate. Second, by being able to grow the seed layer on the substrate of interest and bypassing the transfer method, it provides a cleaner surface of the seed layer for subsequent growth of the material layer, because the growth of the material layer can be formed in situ in the same CVD or growth process. This reduces possible impurities on the surface of the seed layer, thereby allowing a defect-free uniform planar material layer to be formed on the seed layer. For the sake of clarity, it should be appreciated that the subsequent growth of the material layer is not limited to LCVD. Other suitable growth processes for forming the material (e.g., 2D, 3D, or oxide material) layer can be used, wherein the growth process can be implemented in situ. Third, the LCVD process enables the seed layer to be grown at a lower temperature on the base substrate, thereby preserving the original surface of the base substrate and the crystallinity of its material for subsequent growth, especially if the material of the base substrate has low thermal stability (e.g., thermally stable at temperatures below 300° C. or 400° C.). Fourth, the low-temperature laser-assisted CVD process is also compatible with conventional semiconductor processing techniques.

[0015] According to a third aspect, a heterostructure is provided, comprising: a substrate; and a seed layer formed on the substrate, the seed layer comprising a layer of a two-dimensional (2D) single-layer amorphous material having the following disordered atomic structure: it is suitable for generating multiple localized electronic states to form multiple potential wells for binding adsorbed atoms to the surface of the seed layer via van der Waals (vdW) interactions, wherein the multiple potential wells each have a potential energy: it is greater in size than the surrounding thermal energy to trap the adsorbed atoms on the surface of the seed layer.

[0016] The substrate may include one of the following: a metal, a semiconductor, an insulator, a glass, a polymer, silicon, silicon carbide, sapphire, a Group III-V substrate, a Group II-VI substrate, or an oxide.

[0017] When the substrate is a crystalline substrate, the seed layer may be adapted to shield an effect provided by the crystallinity (degree) of the crystalline substrate.

[0018] The heterostructure may include a material layer formed on the seed layer, the material layer being formed by bonding adatoms of the material to a surface of the seed layer via van der Waals (vdW) interactions.

[0019] The material layer may include one or more layers of a 2D material, the 2D material including one of: graphene, borophene, boron nitride, perovskite, transition metal dichalcogenide, or phosphorene.

[0020] The material layers may include one or more layers of Group III-V semiconductor materials.

[0021] The Group III-V semiconductor material may include one of the following: GaAs, GaN, AlN, InP, and InN.

[0022] The material layers may include one or more layers of Group II-VI semiconductor materials.

[0023] The Group II-VI semiconductor material may include one of the following: CdTe, CdS, and ZnS.

[0024] The material layer may include one or more layers of oxide.

[0025] The oxide may include one of the following: hafnium oxide, aluminum oxide, manganese oxide, perovskite, or spinel.

[0026] The seed layer may include a 2D single layer of amorphous carbon.

[0027] According to a fourth aspect, there is provided a device comprising any of the aforementioned heterostructures.

[0028] According to a fifth aspect, a method for forming a material layer on a substrate is provided. The method comprises: forming a seed layer on the substrate, the seed layer comprising a layer of a two-dimensional (2D) monolayer amorphous material having the following disordered atomic structure: it is suitable for generating multiple localized electronic states to form multiple potential wells for binding adsorbed atoms to the surface of the seed layer via van der Waals (vdW) interactions, wherein each of the multiple potential wells has the following potential energy: it is greater than the surrounding thermal energy in size to capture adsorbed atoms on the surface of the seed layer; and forming the material layer on the seed layer by binding the adsorbed atoms of the material to the surface of the seed layer via van der Waals (vdW) interactions.

[0029] The method may include changing the disordered atomic structure of the layer of the 2D monolayer amorphous material to adjust the strength of the vdW interaction between adatoms of the material and the surface of the seed layer.

[0030] The method may include: forming a handling layer on the material layer; and releasing the seed layer from the substrate to form a self-supporting film including the seed layer and the material layer.

[0031] Forming the seed layer on the substrate may include forming the seed layer on the substrate using laser assisted chemical vapor deposition (LCVD).

[0032] Laser-assisted CVD may be performed at temperatures ranging from room temperature (e.g., 20°C) to 400°C, 20°C to 50°C, 20°C to 100°C, 20°C to 150°C, 20°C to 200°C, 20°C to 300°C, 100°C to 200°C, 100°C to 300°C, 200°C to 300°C, 200°C to 400°C, or 300°C to 400°C. In some embodiments, the temperature range of 20°C to 300°C or 20°C to 400°C may be advantageous because it is compatible with industrial processes since complementary metal oxide semiconductor (CMOS) technology typically has temperature limitations within these temperature ranges. For example, nano-sized domains in thin film materials may be destroyed if they are exposed to high temperatures above 300°C or 400°C. In some embodiments, growing the seed layer using LCVD at room temperature may be advantageous because no heating is required for the LCVD growth process and therefore the growth equipment used may not need to be equipped with a heater or suitable thermal insulation / containment. Further, eliminating heating for LCVD growth of the seed layer also reduces energy consumption and thus the overall cost of material growth.

[0033] According to a sixth aspect, a method for enhancing van der Waals (vdW) interactions between adsorbed atoms and a surface of a seed layer to form a material layer on the seed layer is provided. The seed layer comprises a layer of a two-dimensional (2D) monolayer, and the method comprises: generating a disordered atomic structure in the seed layer, the disordered atomic structure of the seed layer being suitable for generating a plurality of localized electronic states to form a plurality of potential wells for binding adsorbed atoms to the surface of the seed layer via vdW interactions to form the material layer, wherein the plurality of potential wells each have a potential energy that is greater in magnitude than the surrounding thermal energy to trap adsorbed atoms on the surface of the seed layer.

[0034] It should be appreciated that features associated with one aspect may be applicable to other aspects. Therefore, an embodiment provides a seed layer comprising a layer of a two-dimensional (2D) monolayer amorphous material having a disordered atomic structure, wherein a plurality of localized electronic states are generated by the disordered atomic structure to form a plurality of potential wells that act as high-energy sites for adsorption of adatoms during the growth of the material layer via vdW interactions. This results in a stronger interaction between the adatoms and the surface of the seed layer and a higher nucleation density of the adatoms on the surface of the seed layer, which together act to enhance the wettability of the adatoms on the surface of the seed layer to achieve uniform planar material layer growth. In addition, the disordered atomic structure of the seed layer can also be adjusted from a completely amorphous phase to a nanocrystalline phase to regulate the interaction between the underlying substrate and the material layer, thereby providing a useful way to remotely control the growth of the material layer. Further, the stronger vdW interaction between the surface of the seed layer and the material layer allows the grown material layer to detach from the underlying substrate to produce a self-supporting film, which can be advantageous in terms of the design of heterostructure electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0036] Figure 1 shows a schematic structure of a heterostructure including a seed layer according to an embodiment;

[0037] Figure 2 A schematic diagram showing a plan view of a seed layer including a single layer of amorphous carbon (MAC) according to an embodiment;

[0038] Figure 3 The following flow chart is shown: Figure 1 The steps of the method for forming a heterostructure;

[0039] Figure 4 The following flowchart is displayed: Figure 1 The steps of forming a self-supporting film comprising a seed layer and a material layer from a heterostructure;

[0040] Figure 5 Show About Figure 4 A schematic diagram illustrating the steps of a method for forming a self-supporting film;

[0041] Figure 6 shows photographs taken of grown MAC films on three different substrates, namely titanium, glass and copper, according to an embodiment;

[0042] Figure 7 show Figure 6 Raman spectra of the as-grown MAC films;

[0043] Figure 8 shows a diagram illustrating theoretical simulation of out-of-plane structural relaxation within a MAC film, which induces local strain within the lattice structure of the MAC film according to an embodiment;

[0044] Fig. 9 Display for Figure 8 A model of theoretical simulation with the squared norm of the wave function superimposed on it to show the localized electron distribution in the atomic structure of MAC;

[0045] Fig.10 A plot showing the optical transmission spectrum of a MAC according to an embodiment;

[0046] Fig.11A and 11B Scanning transmission electron microscopy (STEM) images showing a seed layer with two different structural variations according to an embodiment, wherein Fig.11A STEM images of MAC membranes are shown and Fig. 11B STEM image showing nanocrystalline graphene film;

[0047] Fig. 12A and 12B Raman spectra of MAC before and after temperature treatment at about 700° C. are shown according to an embodiment, wherein Fig. 12A The Raman spectrum of MAC before treatment at this temperature is shown and Fig. 12B The Raman spectrum of MAC after treatment at this temperature is shown;

[0048] Fig.13 show Fig. 12B Transmission electron microscopy (TEM) of MAC after treatment at this temperature;

[0049] Fig.14 A schematic diagram showing a heterostructure including a two-dimensional (2D) material grown on a seed layer on a substrate according to an embodiment;

[0050] Fig.15A schematic diagram showing a heterostructure including a three-dimensional (3D) material grown on a seed layer on a substrate according to an embodiment;

[0051] Fig.16A , 16B 16C and 16C show optical images of MoS2 grown on three different surfaces according to an embodiment, wherein Fig.16A Optical image showing MoS2 grown on silicon dioxide (SiO2), Fig. 16B Optical images showing MoS2 grown on MAC monolayer on SiO2, and Fig. 16C Optical image showing MoS2 grown on MAC few-layer on SiO2;

[0052] Fig.17A and 17B A scanning electron microscopy (SEM) image of MoS2 grown using a sapphire substrate according to an embodiment is shown, wherein Fig.17A SEM images of MoS2 grown directly on sapphire substrate and on MAC monolayer on sapphire substrate are shown, and Fig. 17B Magnified SEM image showing MoS2 grown on MAC monolayer on sapphire substrate;

[0053] Fig.18A and 18B A scanning electron microscopy (SEM) image of MoS2 grown using a sapphire substrate according to an embodiment is shown, wherein Fig.18A SEM images showing MoS2 grown directly on sapphire substrate and on MAC few layers on sapphire substrate, and Fig.18B A magnified SEM image showing MoS2 grown on a MAC few-layer on a sapphire substrate; and

[0054] Fig.19 Atomic force microscopy (AFM) images of In2Se3 grown on a MAC monolayer on a SiO2 substrate according to an embodiment are shown. DETAILED DESCRIPTION

[0055] Exemplary embodiments relate to a seed layer, a method of forming the seed layer, a heterostructure including the seed layer, a device including the heterostructure, a method of forming a material layer using the seed layer, and a method of enhancing vdW interaction between adsorbed atoms and a surface of the seed layer.

[0056] It is understood that in this application, the use of the singular includes the plural unless specifically stated otherwise. It should be noted that when used in the specification and the appended claims, the singular forms "a, an," and "the" include plural referents unless the context clearly dictates otherwise. In addition, the use of the terms "including," and "having," as well as other forms such as "comprising," "having," are not to be considered limiting.

[0057] In the present application, the devices and / or heterostructures as described herein may be capable of operating in various orientations, and therefore it should be understood that when used in the following description, the terms "top", "base", "underlying", etc. are used for convenience and to assist in the understanding of relevant positions or directions, and are not intended to limit the orientation of the devices and / or heterostructures.

[0058] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0059] In the present embodiment, by using a seed layer comprising a layer of a two-dimensional (2D) monolayer amorphous material having a disordered atomic structure (wherein a plurality of localized electronic states are generated by the disordered atomic structure to form a plurality of potential wells), the seed layer has high energy sites for adsorption of adatoms during growth of the material layer via vdW interactions. The plurality of localized electronic states refers to the distribution of a plurality of electronic states within the 2D monolayer amorphous material that are not extended to overlap each other. In particular, in a disordered material system, these localized electronic states are sufficiently separated from each other, which may result in the absence of electrical conduction of the 2D monolayer amorphous material. The potential wells formed by the plurality of localized electronic states of the 2D monolayer amorphous material refer to capture sites whose potential energy is greater in magnitude than the available ambient thermal energy to capture adatoms on the surface of the seed layer, preferably at the locations of these potential wells. These potential wells formed by multiple localized electronic states generated by the disordered atomic structure of the 2D monolayer amorphous material provide strong interactions between the adatoms and the surface of the seed layer and high nucleation density of the adatoms on the surface of the seed layer, which work together to enhance the wettability of the adatoms on the surface of the seed layer to achieve subsequent uniform planar material layer growth. In this case, enhancing the wettability of the adatoms refers to improving the attractive force between the adatoms and the surface of the seed layer so that the attractive force is stronger than the attractive interaction force between the adatoms. Enhancing the wettability of the adatoms results in a uniform distribution of the adatoms on the surface of the seed layer, rather than forming clusters of adatoms on the surface. In addition, the disordered atomic structure of the seed layer can also be adjusted from a completely amorphous phase to a nanocrystalline phase to regulate the interaction between the underlying substrate and the material layer, thereby providing a useful way to remotely control the growth of the material layer. Further, the strong vdW interaction between the surface of the seed layer and the material layer allows the grown material layer to be detached from the underlying substrate to produce a self-supporting film, which can be advantageous for heterostructure electronic devices. In this context, the term "amorphous material" refers to a material that lacks the long-range order typical of crystalline materials. The term "monolayer" refers to a one-atom-thick layer that can range from a few angstroms to to a few nanometers thick.

[0060] Figure 1 A schematic structure of a heterostructure 100 according to an embodiment is shown. The heterostructure 100 includes a seed layer 102 formed on a substrate 104. Figure 1As shown in FIG. 1 , the seed layer 102 is formed directly on the substrate 104 (i.e., the seed layer 102 is formed on top of and adjacent to the substrate 104). The substrate 104 provides structural support for the seed layer 102. The heterostructure 100 also includes a material layer 106 formed on the seed layer 102. The material layer 106 includes any material of interest and will be described below with respect to Fig.14 and 15 This is further described. The seed layer 102 includes a layer of a two-dimensional (2D) monolayer amorphous material having a disordered atomic structure. The disordered atomic structure is suitable for generating multiple localized electronic states to form multiple potential wells for bonding adsorbed atoms to the surface of the seed layer 102 via van der Waals (vdW) interactions to form a material layer 106. The seed layer 102 including the layer of the 2D monolayer amorphous material can be formed of any 2D material, as long as the seed layer 102 has a disordered atomic structure that generates multiple localized electronic states to form multiple potential wells for enhancing the vdW interaction between the adsorbed atoms and the surface of the seed layer 102.

[0061] In the embodiments described below, a monolayer amorphous carbon (MAC) is used as an exemplary 2D monolayer amorphous material for the seed layer 102. The following description will be made with respect to using one or more layers of MAC as the seed layer 102. Figure 2-19 MAC includes sp 2 A bonded carbon lattice that retains vdW interactions similar to a graphene monolayer, but provides additional vdW interactions due to its disordered atomic structure that produces multiple localized electronic states that can act as a driving force for aligning in-plane adatoms with the surface of the MAC. When using MAC as a seed layer 102, this results in higher surface wettability of the adatoms on the surface of the seed layer 102 (e.g., when compared to graphene or other crystalline 2D materials), thereby enabling uniform and planar growth of the material layer 106. This makes MAC an ideal candidate as a seed layer 102 for epitaxial and / or non-epitaxial growth of a wide variety of material films, in contrast to, for example, graphene.

[0062] Figure 2 A schematic diagram of a plan view 200 of a seed layer including a MAC is shown. Figure 2 As shown in , MAC includes unordered sp 2A disordered atomic arrangement and continuous network of carbon (C) atoms in two-dimensional (2D) form and without any grain boundaries (homogeneous). This is in contrast to conventional polycrystalline graphene (inhomogeneous) which includes ordered crystalline domains separated by grain boundaries. Due to the lack of grain boundaries in the MAC seed layer 102, the disclosed MAC seed layer 102 is ultra-strong, making it suitable for applications that may require deformation, such as bending and stretching. In the MAC, the ratio of hexagonal carbon rings to the total number of carbon rings (i.e., the total number of hexagonal and non-hexagonal carbon rings) may be less than 1.

[0063] Figure 3 The following flow chart is shown: Figure 1 The method 300 of the heterostructure 100 includes steps.

[0064] In step 302, a seed layer 102 is formed on a substrate 104. In the present embodiment, the seed layer 102 includes a single layer of amorphous carbon (MAC), and the substrate 104 includes a sapphire substrate. In the present embodiment, the MAC is formed at room temperature using a laser-assisted chemical vapor deposition (LCVD) process with hydrocarbons as precursors (e.g., CH4, C2H2, etc.). Hydrogen (H2) and argon (Ar) may also be mixed with the precursor. In the LCVD process, the laser acts as both an energy source for decomposing the precursor gas in a process called photolytic decomposition and a local heat source. In the present embodiment, the LCVD process for manufacturing the MAC seed layer 102 uses the following parameters: (i) process gas: C2H2; (ii) chamber pressure: 2x10 -2 mbar; (iii) laser fluence: 70 mJ / cm; (iv) growth time: 1 minute; (v) plasma power: 5 W. Although an LCVD process is used to form the MAC in the present embodiment, it will be appreciated that an LCVD process may also be used to form the non-carbon-based seed layer 102 in other embodiments.

[0065] For the growth process, the above exemplary process uses acetylene (C2H2) in the growth chamber. The gas pressure in the chamber is always controlled to 2x10 -2mbar. The gas was in the presence of a plasma generator operating at 5W power. Growth began when a 248nm excimer laser was exposed to the surface of the sapphire substrate 104 at a fluence of 70mJ / cm and a pulse frequency of 50Hz. The laser exposure time (i.e., growth duration) was set to 1 minute to obtain a continuous MAC seed layer 102 on the substrate 104. In this growth, no stage heater was used. In order to control and / or change the properties of the disclosed MAC seed layer 102, multiple parameters disclosed herein can be adjusted, including, but not limited to, hydrocarbons as precursors, precursor mixtures, adjustments to the photolysis decomposition process and equipment, temperature adjustments, substrate temperature adjustments, changes in C values, changes in the number of atomic layers, sp 2 Change to sp 3 The ratio of MAC seed layer 102 to MAC seed layer 104 is determined by the following method:

[0066] Further, it should be appreciated that the use of a photolytic decomposition method to form the seed layer 102 as described above is different from a typical method of forming a 2D material film using, for example, thermal CVD (TCVD). In particular, TCVD requires a hot substrate to cause chemical reactions of bond breaking and bond formation of adsorbed atoms on the surface of the substrate. However, the temperature required for such reactions to occur is typically much higher than the crystallization temperature of the 2D material. This means that at the lowest growth temperature required to form a 2D material film on the surface of the substrate, the atoms of the 2D material deposited on the surface of the substrate are highly mobile (e.g., surface diffusion) and will rearrange themselves, resulting in some degree of crystallization during the formation of the 2D material. As a result, the 2D material film formed will have varying degrees of crystallinity and may not be completely or fully amorphous. In contrast, by using a photolytic decomposition method, when the atoms of the 2D material are deposited on the surface of the substrate at a lower temperature (e.g., at room temperature, or at a temperature below the crystallization temperature), the energy from the laser breaks the bonds of the precursor gas and provides additional energy for subsequent 2D material film formation. Therefore, by using a photolytic decomposition method at low temperature, the deposited atoms of the 2D material have low mobility and are unlikely to move after landing on the surface of the substrate. The restriction in atomic motion (surface diffusion) of the atoms prevents the crystal formation of the 2D material. Therefore, a single layer amorphous film can be formed.

[0067] By using a photolysis decomposition method to form a MAC seed layer 102 as described above, many advantages can be provided. First, the MAC seed layer 102 synthesized by LCVD can be integrated with existing semiconductor processing technology. In particular, LCVD is an industrially scalable process that can achieve high yields of large-area films. Therefore, the LCVD process for seed layer formation can be easily integrated with current semiconductor processing technology, making the process industrially compatible and scalable. In addition, LCVD is an ultrafast deposition technology in which the entire surface of the substrate 104 can be covered with a MAC film in less than 60 seconds. Therefore, LCVD is more efficient than the widely used atomic layer deposition (ALD) process.

[0068] Second, the use of LCVD means that the MAC seed layer 102 can be synthesized at low temperatures, below 300°C (e.g., as low as 200°C or even at room temperature), which is compatible with silicon-based technologies. Moreover, in contrast to the growth of graphene, the cost of MAC growth using LCVD is significantly lower because less energy is required for LCVD growth than for conventional thermal chemical vapor deposition of graphene, which requires temperatures of about 1000°C. Further, a reduction in the synthesis temperature (e.g., to a temperature of 20°C-150°C) can enable direct MAC growth on polymer substrates for OLEDs and flexible electronic devices. Low temperature growth of MAC as a seed layer 102 is also advantageous because it minimizes lattice damage or surface reconstruction of a single crystal substrate, thereby maintaining a pristine and smooth interface between the seed layer 102 and the substrate 104.

[0069] Third, in the case of low temperature photolytic growth of MAC by LCVD, direct growth of MAC seed layer 102 can be performed on a wide variety of substrates, including Si, single crystal, polycrystalline, metal, glass, polymer, etc. Moreover, the subsequent growth of material layer 106 on seed layer 102 is dominated by the vdW interaction of the surface of the MAC seed layer and the adsorbed adatoms, thereby minimizing the effect of substrate 104 on the subsequent material growth. In particular, one or more layers of MAC can be adapted to shield the underlying substrate 104 crystalline information and thus dominate the subsequent growth mechanism.

[0070] In step 304, a material layer 106 is formed or deposited on the seed layer 102. Due to the stronger vdW interaction between the adatoms and the surface of the seed layer 102 as provided by the disordered atomic structure of the seed layer 102, a wide variety of materials may be used to form the material layer 106. Fig.14 and 15This is further described. It will therefore be appreciated that a number of growth or deposition techniques may be used to form the material layer 106, depending on the material used for the material layer 106. Examples of applicable deposition techniques include molecular beam epitaxy (MBE), atmospheric pressure CVD (APCVD), metal organic CVD (MOCVD), plasma enhanced CVD (PECVD), thermal CVD (TCVD), and atomic layer deposition (ALD). Figure 16A-19 , embodiments of different materials for forming material layer 106 are discussed.

[0071] Figure 4 The following flowchart is shown: Figure 1 The steps of method 400 of forming a free-standing film of the heterostructure 100 including the seed layer 102 and the material layer 106 are shown.

[0072] In step 402, an operating layer is formed on the material layer 106. In other words, the operating layer is formed on and adjacent to the material layer 106. The operating layer includes a metal stressor layer, a flexible tape layer, or an adhesive material layer that may have stronger adhesion to the underlying material layer 106 than the adhesion between the seed layer 102 and the substrate 104.

[0073] In step 404, the seed layer 102 is detached from the substrate 104 to form a self-supporting film. This is achieved by peeling or stripping the material layer 106 and the seed layer 102 from the substrate 104 to form a self-supporting film, and then removing the operating layer formed or attached to the material layer 106. Peeling is dominated by a stronger interaction between the seed layer 102 and the material layer 106 than the interaction with the substrate 104. The stronger interface between the seed layer 102 and the material layer 106, and the non-covalent bonding of the seed layer 102 to the underlying substrate 104 help to peel the self-supporting film from the substrate 104. This is advantageous because the self-supporting film including the seed layer 102 and the material layer 106 can be separated and used in, for example, flexible and transparent optoelectronic devices, and the substrate 104 can be reused.

[0074] Figure 5 Display pair Figure 4 Schematic diagram 500 is provided to illustrate the steps of the method 400 for forming a self-supporting film. In this embodiment, a double layer of MAC is formed on a substrate 510 and used as a seed layer 512. A double layer of 2D material is formed on the seed layer 512 as a material layer 514.

[0075] As shown in schematic diagram 502, an operating layer 516 is formed on top of material layer 514. This corresponds to step 402 as described above.

[0076] As shown in schematic 504, the peeling or exfoliation of material layer 514 and seed layer 512 from substrate 510 is performed using handling layer 516. A detached free-standing layer 518 includes material layer 514 and seed layer 512.

[0077] As shown in schematic 506, the operating layer 516 is then removed from the self-supporting layer 518. The operating layer 516 can be removed, for example, by the following means. When the operating layer 516 is a metal stressor layer, it can be removed by immersing the operating layer 516 in a metal etchant. When the operating layer 516 is a flexible tape layer, the flexible tape layer can include heat release or UV release adhesion, which can be removed by heating the tape or exposing it to UV light, respectively.

[0078] Figure 6 Photographs 600 taken of grown MAC films on three different substrates, namely titanium, glass, and copper, are shown. Figure 6 As shown in FIG. 6 , photo 602 shows a grown MAC film on a titanium substrate, photo 604 shows a grown MAC film on a glass substrate, and photo 606 shows a grown MAC film on a copper substrate. As is clear from at least photo 604, the deposited MAC film is transparent in visible light.

[0079] Figure 7 show Figure 6 Raman spectra of the grown MAC films. Raman spectrum 702 is obtained using a MAC film grown on a glass substrate, Raman spectrum 704 is obtained using a MAC film grown on a titanium substrate, and Raman spectrum 706 is obtained using a MAC film grown on a copper substrate. Figure 7 As shown in all Raman spectra 702, 704, and 706, there is no 2D peak (at about 2700 cm -1 In contrast, the Raman spectra 702, 704, 706 all show a broad G peak 708 (at about 1600 cm -1 ) and D peak 710 (at about 1350 cm -1 The broadening of the D and G peaks generally indicates a transition from nanocrystalline graphene to an amorphous film. The Raman spectra 702, 704, 706 also show a D / G ratio in the range of about 0.5-1. This D / G ratio combined with the absence of the 2D peak distinguishes the disordered atomic structure of MAC from that of 2D graphene and diamond. The Raman spectra 702, 704, 706 also confirm the growth of the grown MAC films on these three different substrates.

[0080] Figure 8A diagram 800 is shown illustrating a theoretical simulation of out-of-plane structural relaxation within a MAC film 802, which induces local strain in the lattice structure of the MAC film 802. In this theoretical simulation, the atomic coordinates of the atoms of the MAC film 802 in the model are initially arranged in a flat 2D plane. By taking into account the interaction forces between these atoms, an atomic rearrangement of these atoms occurs in 3D space, and the atomic coordinates of the atoms of the MAC film 802 occupy their new equilibrium positions in which the structure of the MAC film 802 is in its most stable configuration with the lowest internal energy. As shown in diagram 800, the simulated MAC film 802 is a single layer and has about The amorphous or disordered atomic structure of the MAC film 802 produces a strained 2D lattice with a localized electron distribution, thereby providing a surface with relatively high energy. Such a surface induces strong interactions with adsorbed adatoms, resulting in higher surface wettability required for uniform and planar 2D and / or 3D material film formation. This helps to overcome the low wetting of 3D material films on 2D surfaces for vdW epitaxy due to the inherently lower surface energy of the surfaces of 2D crystalline materials.

[0081] Further, the higher surface energy of MAC 802 due to its disordered atomic arrangement and enhanced vdW interaction results in a high number of nucleation sites for the adsorbed adatoms on the MAC seed layer. The high number of nucleation sites (or higher nucleation density) can significantly reduce the growth rate and temperature requirements for the subsequent material layer growth, making the growth process more energy-efficient and cost-effective. In addition, the enhanced vdW interaction between MAC 802 (i.e., seed layer) and the material layer (or epitaxial layer) results in a stronger interface that is stable even during the subsequent high-temperature growth process. This ensures the uniformity of the subsequent formation of a planar material layer and prevents or reduces the formation of islands and / or clusters during the subsequent growth of the material layer. Note that the formation of islands and / or clusters in the material layer results in a non-planar active layer material film, which is detrimental to the device performance of subsequent devices formed using such non-planar material layers.

[0082] Fig. 9 Display for Figure 8 Model 900 of a theoretical simulation of MAC 802. Model 900 is superimposed with the norm square of the wave function to show the localized electron distribution 902 in the atomic structure of MAC 802.

[0083] like Fig. 9As shown in the model 900 of MAC film, a 1-atom-thick carbon film has a mixture of hexagonal and non-hexagonal rings in its structure. The rings are completely connected to each other, forming a network of polygons in the form of a large-area film with a scale of at least micrometers. The ratio of the number of hexagonal rings to the total number of carbon rings (i.e., the total number of hexagonal and non-hexagonal rings) is a measure of crystallinity (or amorphism), C. Non-hexagons are in the form of 4, 5, 7, 8, 9-membered rings. Fig. 9 5-membered rings 904 and 7-membered rings 906 are shown in contrast to the regular 6-membered rings 908 typical of crystalline graphene. The disclosed embodiments may demonstrate C values ​​ranging between 0.5-0.8, inclusive. This is different from graphene, where C=1 due to the pure hexagonal network.

[0084] Fig.10 Plot 1000 showing the optical transmission spectrum of a MAC 1002 according to an embodiment.

[0085] Plot 1000 illustrates the optical transparency of MAC 1002 over a range of optical wavelengths. Fig.10 As shown in , the optical transparency is ˜98.1% at a wavelength of light of 550 nm, and the transparency increases as the wavelength of light increases. Thus, embodiments of the present invention provide MACs having an optical transparency equal to or greater than 98% at wavelengths of 550 nm or higher. The disclosed MACs are different from graphene. Line 1004 shows the theoretical limit of 97.7% of the optical transparency of graphene. Thus, at least as evidenced by plot 1000, the MAC 1002 of the present embodiment exhibits a higher optical transparency at wavelengths of about 550 nm or higher than graphene. In particular, the transparency of the MAC 1002 does not decrease rapidly at short wavelengths (<400 nm). This may be due in part to fewer contaminants during the growth of the MAC 1002, since the MAC 1002 can be grown on any substrate without using a transfer method. The high optical transparency of MAC in the visible range (~98.1% at 550 nm and increasing at higher wavelengths) makes MAC an ideal candidate for seed layers on transparent substrates (e.g., glass or suitable polymers) for forming subsequent active semiconductor films for transparent devices.

[0086] Fig.11A and 11B Scanning transmission electron microscopy (STEM) images 1100, 1110 of a seed layer having two different structural variations are shown according to an embodiment, wherein Fig.11A STEM image 1100 showing a MAC membrane and Fig. 11B STEM image 1110 of a nanocrystalline graphene film is shown. Fig. 11BThe "white" clusters 1112 shown in FIG. 1 are related to contaminants absorbed on the surface of the nanocrystalline graphene film and have nothing to do with the crystallinity of its atomic structure.

[0087] Depending on the synthesis conditions, the carbon-based seed layer can range from a completely amorphous layer (e.g., MAC) to nanocrystalline sp 2 -A wide range of atomic structural changes of the carbon layer (e.g., nanocrystalline graphene layer) is possible. In addition, a seed layer ranging from a single layer to a multilayer stack on a substrate can be formed. Such structural changes can adjust the vdW interaction between the seed layer and the material layer (or epitaxial layer), and can remotely adjust the interaction between the substrate and the adsorbed atoms to form the material layer during growth. For example, by adjusting the crystallinity of the seed layer from fully amorphous to nanocrystalline, a greater interaction between the substrate and the adsorbed atoms can be achieved because the multiple potential wells of the disordered atomic structure of the 2D amorphous seed layer provide shielding for the crystallinity effect of the substrate.

[0088] One example of adjusting the crystallinity of the carbon-based seed layer may be performed using laser-based growth conditions similar to those described with respect to step 302, but using, for example, a methane precursor gas and a copper foil substrate. Fig. 11B The temperature of the copper foil can be set in the range of 500°C to 600°C to form a completely amorphous film such as Fig.11A As shown in , the temperature of the copper foil can be set to below 400° C. This is because higher substrate temperatures during growth result in a more crystalline material.

[0089] Fig. 12A and 12B Raman spectra 1200, 1210 of MAC before and after temperature treatment at about 700°C are shown according to an embodiment, wherein Fig. 12A The Raman spectrum of MAC before the temperature treatment is shown in 1200 and Fig. 12B The Raman spectrum 1210 of the MAC after the temperature treatment is shown.

[0090] Fig. 12A Raw data 1202 obtained by Raman spectroscopy of the MAC before temperature treatment is shown, which fits the D band 1204 and the G band 1206, while Fig. 12BRaw data 1212 obtained by Raman spectroscopy of the MAC after this temperature treatment is shown, which fits the D band 1214 and the G band 1216. As shown in the Raman spectra 1200, 1210, the shapes of the D bands 1204, 1214 and the G bands 1206, 1216 and their D / G ratios are similar. This confirms that there is no observable change in the crystallinity or grain size of the MAC after heat treatment at about 700°C. Therefore, the MAC is thermally stable at high temperatures of ~700°C, making the MAC a stable seed layer for subsequent high temperature growth material layers. It will be appreciated that since the MAC is thermally stable at a temperature of ~700°C, it is also thermally stable at any temperature below 700°C.

[0091] Fig.13 show Fig. 12B Transmission electron microscopy (TEM) image 1300 of MAC after the temperature treatment. The TEM image 1300 of MAC has a 10×10 nm 2 The size of Fig.13 The clusters 1302 shown in FIG. 1300 are contaminants covering some areas of the MAC. The contaminant clusters 1302 may be formed due to the transfer process from the substrate (eg, copper foil) to the TEM grid for taking the TEM image 1300 and have nothing to do with the crystallinity of the MAC. Fig.13 The inset 1304 of FIG. 1 is a Fourier transform of the TEM image 1300 and shows the diffraction pattern of the TEM image 1300. In particular, the inset 1304 shows an amorphous halo, rather than clear rings or individual spots indicating nanocrystalline graphene or polycrystalline graphene, respectively.

[0092] In addition to MAC being a thermally stable layer, MAC also has high thermal conductivity, which enables it to act as a heat diffusion layer in a heterostructure including an active semiconductor epitaxial layer to transfer heat to a heat sink. This is advantageous because thermal management is an essential part of thin film devices such as LEDs. The ability of MAC to quickly diffuse heat helps avoid overheating and degradation of device performance.

[0093] Fig.14 A schematic diagram of a heterostructure 1400 including a two-dimensional (2D) material layer 1402 grown on a seed layer 1404 on a substrate 1406 is shown according to an embodiment. The heterostructure 1400 has a structure similar to Figure 1 The heterostructure 100 shown in FIG. 1 may be similar in structure to that shown in FIG. Figure 3 Method 300 of forming or manufacturing.

[0094] The seed layer 1404 includes a single layer of amorphous 2D material (e.g., MAC in this embodiment, but other single layers of 2D amorphous materials may also be used) grown directly on a substrate 1406. The substrate 1406 in this embodiment includes SiO2, but other substrates such as Si, SiC, sapphire, III-V materials, II-VI materials, oxides, etc. may also be used. The seed layer 1404 grown on the substrate 1406 is used to stabilize the subsequent growth of the 2D material layer 1402 by utilizing the strong vdW interaction between the adsorbed atoms of the 2D material layer 1402 and the surface of the seed layer 1404. This advantageously helps to circumvent the strict requirement of using a dedicated substrate for the stable growth of the 2D material layer 1402.

[0095] Although Fig.14 A single layer of amorphous carbon (MAC) is shown as the seed layer 1404, but multiple layers of MAC may also be used by direct growth or transfer methods. The grown 2D material layer 1402 includes one or more of the following layers: a single layer of 2D amorphous film, a 2D crystalline film, graphene, black phosphorene, borophene, hexagonal boron nitride (hBN) or boron nitride, transition metal dichalcogenide (TMD), perovskite and / or boron phosphide (BP). The 2D material layer 1402 may be grown on the seed layer 1404 using deposition techniques such as metal-organic chemical vapor deposition (MOCVD), thermal chemical vapor deposition (TCVD), plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD). The 2D-2D composite structure (i.e., a self-supporting structure including layers 1402, 1404) may be detached from the substrate 1406 after growth to form a self-supporting stack, which may be further integrated into the manufacturing process of thin film and flexible optoelectronic devices.

[0096] Fig.15 The structure of a heterostructure 1500 including a three-dimensional (3D) material layer 1502 grown on a seed layer 1504 on a substrate 1506 according to an embodiment is shown. The heterostructure 1500 has the same Figure 1 The heterostructure 100 shown in FIG. 1 may be similar in structure to that shown in FIG. Figure 3 The heterostructure 1500 is formed or manufactured by the method 300. The difference between the heterostructure 1500 and the heterostructure 1400 is that the material layer 1502 grown on the seed layer 1504 is a 3D material layer, which is in contrast to the 2D material layer 1402 included in the heterostructure 1400.

[0097] Different embodiments are described below including different types of used 3D materials and substrates.

[0098] i) Integration of CMOS compatible substrates (e.g. Si or Ge) with III-V semiconductor planar thin films

[0099] In this embodiment, a layer of MAC is formed on a Si or Ge substrate 1506. The MAC acts as a seed layer 1504 for the subsequent epitaxial or non-epitaxial growth of one or more layers 1502 of III-V semiconductors (e.g., GaAs, GaN, AlN, InP, InN, etc.) using existing deposition techniques (e.g., MOCVD, TCVD, PECVD, ALD, etc.). The III-V semiconductor materials can be used as active layers for applications such as light emitting diodes (LEDs), infrared (IR) sensors, photodetectors, and other optoelectronic devices.

[0100] ii) II-VI semiconductor thin films

[0101] The ability to integrate II-VI thin film semiconductors (e.g., CdTe, CdS, ZnS, etc.) on arbitrary substrates (e.g., Si, semiconductor materials, glass, metal foils, polymers, etc.) is advantageous for solar cell, photovoltaic, and aerospace applications. As discussed above, achieving uniform planar material layers by vdW epitaxy is challenging due to low wettability on the epitaxial surface. In this embodiment, a MAC layer 1504 acting as a seed layer 1504 may be formed on a substrate 1506 for epitaxial or non-epitaxial growth of a layer 1502 of a 3D planar film of a II-VI semiconductor. Examples of 3D films of Group II-VI semiconductor materials include CdTe, CdS, ZnS, etc.

[0102] iii) Oxide film

[0103] Oxide thin films, including simple metal oxides (Hf2O3, Al2O3, MnO, etc.) and complex oxides (perovskites, spinels, etc.), play a significant role in a wide variety of electronic, spintronic, magnetoelectric, and energy storage devices due to their functional properties. These oxides can act as dielectrics, piezoelectric materials, thermoelectric materials, etc. Fig.15 In a similar scheme as shown in , one or more layers of oxide 1502 can be deposited on a substrate 1506 using MAC as a seed layer 1504. The substrate 1506 in this application can be any arbitrary substrate such as Si, semiconductor material, glass, metal foil, polymer, etc. Figure 4 and 5 The described method 400 peels off the deposited oxide film layer 1502 to obtain a free-standing film.

[0104] Fig.16A , 16B 16C and 1600 show optical images 1610, 1620 of MoS2 grown on three different surfaces according to an embodiment, wherein Fig.16A Optical image 1600 showing MoS2 grown on silicon dioxide (SiO2), Fig. 16B Optical image 1610 showing MoS2 grown on a MAC monolayer on SiO2, and Fig. 16C Optical image 1620 of MoS2 grown on MAC few layers on SiO2 is shown.

[0105] In this embodiment, first, as in Figure 3 As described in step 302 of , MAC is grown on a SiO2 substrate using an LCVD method. The growth conditions of MAC on a SiO2 substrate are the same as those described for a sapphire substrate with respect to step 302, and for the sake of brevity, these are not repeated here. The one or more MAC layers act as seed layers for the subsequent growth of a MoS2 layer. The MoS2 layer is a 2D material grown on top of the one or more MAC layers by thermal CVD. The parameters for the thermal CVD growth of the MoS2 layer are as follows: MoO3+S, atmospheric pressure chemical vapor deposition (APCVD), 750°C, 20 sccm Ar, and 10 minutes growth time.

[0106] As in Fig.16A , 16B As demonstrated in 16C and 16D, MoS2 layers grow differently on these three different surfaces (i.e., no MAC, MAC monolayer, and MAC minority layer, respectively). Fig.16A As shown in the optical image 1600 of , standard MoS 2 grown on SiO 2 forms triangular crystals 1602 . Fig. 16B The optical image 1610 shows that using a single MAC layer as a seed layer leads to the growth of MoS2 crystals 1612 with irregular shapes and multilayer centers. Fig. 16C As shown in the optical image 1620, using a MAC few layer as a seed layer leads to high density nucleation of MoS2 crystals.

[0107] Fig.17A and 17B Scanning electron microscopy (SEM) images 1702, 1704, 1710 of MoS2 grown using a sapphire substrate according to an embodiment are shown, wherein Fig.17A SEM images 1702, 1704 of MoS2 grown directly on a sapphire substrate and on a MAC monolayer on a sapphire substrate, respectively, are shown, and Fig. 17B A magnified SEM image 1710 is shown of MoS2 grown on a MAC monolayer on a sapphire substrate. Fig.18A and 18B Scanning electron microscopy (SEM) images 1802, 1804, 1810 of MoS2 grown using a sapphire substrate according to an embodiment are shown, wherein Fig.18ASEM images 1802, 1804 of MoS2 grown directly on a sapphire substrate and on a MAC few-layer on a sapphire substrate, respectively, are shown, and Fig.18B A magnified SEM image 1810 is shown of MoS2 grown on a MAC few-layer on a sapphire substrate.

[0108] In this embodiment, first, as in Figure 3 As described in step 302 of , MAC is grown on a sapphire substrate using an LCVD method. The one or more MAC layers act as seed layers for the subsequent growth of a MoS2 layer. The growth conditions of MAC on a sapphire substrate have been described above with respect to step 302, and for the sake of brevity, these are not repeated here. The MoS2 layer is a 2D material grown by thermal CVD on top of the one or more MAC layers. The parameters for the thermal CVD growth of the MoS2 layer are as follows: MoO3+S, atmospheric pressure chemical vapor deposition (APCVD), 850°C, 20sccm Ar, and 5 minutes growth time.

[0109] As in Fig.17A , 17B , 18A and 18B, MoS2 layers grow differently on these three different surfaces (i.e., no MAC, MAC monolayer and MAC few layers, respectively). Fig.17A and 18A As shown in the SEM images 1702 and 1802 of , standard MoS2 grown on sapphire forms triangular crystals 1706, 1806. Fig. 17B The SEM image 1710 shows that using a single MAC layer as a seed layer results in a high density of nucleation of MoS2 crystals 1712 having a triangular shape. Fig.18B As shown in the SEM image 1810, using the MAC few layer as a seed layer results in a high density nucleation of MoS2 crystals 1812 having a dendrite shape.

[0110] Fig.19 An atomic force microscopy (AFM) image 1900 is shown of indium selenide (In2Se3) grown on a MAC monolayer on a SiO2 substrate in accordance with an embodiment.

[0111] First, MAC is grown on a SiO2 substrate or transferred to a SiO2 substrate, where MAC acts as a seed layer for the subsequent growth of In2Se3. In2Se3 is a 2D material that is subsequently grown on MAC using molecular beam epitaxy (MBE). In this embodiment, at a base pressure of 6×10 –10In2Se3 was grown in a 1000 ft MBE chamber. Ultrapure In2Se3 powder (99.99%) was evaporated from a crucible heated by an electron beam source and maintained at 150°C. The chamber pressure during growth was ~6×10 –9 Entrust.

[0112] When using a MAC monolayer as a seed layer, the In2Se3 layer grows in a different manner compared to growing an In2Se3 layer on graphene or directly on a SiO2 substrate without MAC. As shown in AFM image 1900, the In2Se3 crystals 1902 formed using a MAC monolayer as a seed layer retain a range of The thickness of the In2Se3 crystals is about 10 nm (i.e., the thickness of a monolayer) to about 7 nm thick triangular facets. On the other hand, if In2Se3 is grown on a graphene layer on a SiO2 substrate, the grown In2Se3 crystals will be monolayer thick and have a triangular shape. If In2Se3 is grown directly on a SiO2 substrate, the grown In2Se3 crystals have a highly disordered bulk (3D) structure.

[0113] Alternative embodiments of the present invention include: (i) the seed layer 102 includes one or more layers of 2D amorphous materials selected from one or more of the following: amorphous MoS2, amorphous In2Se3, amorphous transition metal dichalcogenides, amorphous black phosphorene, amorphous borophene, amorphous boron nitride; (ii) the substrate 104 is selected from one of the following: Si, SiC, sapphire, III-V group materials, II-VI group materials, oxide semiconductor materials, glass, metals and polymers; (iii) the material layer 106 is selected from 2D materials or 3D materials, and examples of 2D materials and 3D materials are about Fig.14 and 15 provided; and (iv) the material layer 106 may be formed by various deposition techniques such as LPCVD, APCVD, MOCVD, TCVD, PECVD, MBE, and ALD.

[0114] Although only certain embodiments of the present invention have been described in detail, many variations are possible according to the appended claims. For example, features described with respect to one embodiment may be incorporated into one or more other embodiments, and vice versa.

Claims

1. A seed layer for inducing nucleation to form a material layer, the seed layer comprising a layer of a two-dimensional (2D) single-layer amorphous material having a disordered atomic structure, the disordered atomic structure producing a strained 2D lattice of the layer of the 2D single-layer amorphous material and causing atomic rearrangement of the layer of the 2D single-layer amorphous material in a three-dimensional (3D) space to produce localized electronic states to form potential wells for binding adsorbed atoms to the surface of the seed layer via van der Waals (vdW) interactions to form the material layer, wherein the potential wells each have a potential energy that is greater in size than the surrounding thermal energy to trap adsorbed atoms on the surface of the seed layer, wherein the layer of the 2D single-layer amorphous material comprises a homogeneous 2D single-layer amorphous carbon.

2. The seed layer of claim 1, wherein the seed layer has an optical transparency greater than 98% at a wavelength of light between 550 nm and 800 nm.

3. The seed layer of claim 1 or claim 2, wherein the seed layer is thermally stable at a temperature of 700°C.

4. The seed layer of claim 1 or claim 2, wherein the seed layer further comprises one or more additional layers of 2D monolayer amorphous carbon deposited on the layer of the 2D monolayer amorphous material to form a multilayer structured seed layer, thereby regulating the vdW interaction between the seed layer and the material layer.

5. A heterostructure comprising: substrate; and A seed layer is formed on the substrate, the seed layer comprising a layer of a two-dimensional (2D) single-layer amorphous material having a disordered atomic structure that produces a strained 2D lattice of the layer of the 2D single-layer amorphous material and causes atomic rearrangement of the layer of the 2D single-layer amorphous material in a three-dimensional (3D) space to produce localized electronic states to form potential wells for binding adsorbed atoms to the surface of the seed layer via van der Waals (vdW) interactions, wherein the potential wells each have a potential energy that is greater in size than the surrounding thermal energy to trap adsorbed atoms on the surface of the seed layer, wherein the layer of the 2D single-layer amorphous material comprises a homogeneous 2D single-layer amorphous carbon.

6. The heterostructure of claim 5, wherein the substrate comprises one of the following: a metal, an insulator, a glass, a polymer, an oxide, and a semiconductor.

7. The heterostructure of claim 6, wherein the semiconductor comprises silicon, silicon carbide, a Group III-V substrate, or a Group II-VI substrate, and wherein the oxide comprises sapphire.

8. The heterostructure of any one of claims 5 to 7, wherein the substrate is a crystalline substrate, and the seed layer is adapted to shield the effect provided by the crystallinity of the crystalline substrate.

9. The heterostructure according to any one of claims 5 to 7, further comprising a material layer formed on the seed layer, the material layer being formed by bonding adatoms of the material to a surface of the seed layer via van der Waals (vdW) interactions.

10. The heterostructure of claim 9, wherein the material layer comprises one or more layers of a 2D material, the 2D material comprising one of the following: graphene, borophene, boron nitride, perovskite, transition metal dichalcogenide, or phosphorene.

11. The heterostructure of claim 9, wherein the material layer comprises one or more layers of Group III-V semiconductor material.

12. The heterostructure of claim 11, wherein the Group III-V semiconductor material comprises one of the following: GaAs, GaN, AlN, InP, and InN.

13. The heterostructure of claim 9, wherein the material layer comprises one or more layers of Group II-VI semiconductor material.

14. The heterostructure of claim 13, wherein the Group II-VI semiconductor material comprises one of the following: CdTe, CdS, and ZnS.

15. The heterostructure of claim 9, wherein the material layer comprises one or more layers of an oxide.

16. The heterostructure of claim 15, wherein the oxide comprises one of the following: hafnium oxide, aluminum oxide, manganese oxide, perovskite, or spinel.

17. The heterostructure of claim 9, wherein the seed layer further comprises one or more additional layers of 2D monolayer amorphous carbon deposited on the layer of the 2D monolayer amorphous material to form a seed layer of a multilayer structure, thereby regulating the vdW interaction between the seed layer and the material layer and remotely regulating the interaction between the substrate and the adsorbed atoms to form the material layer during growth.

18. A device comprising the heterostructure according to any one of claims 5 to 7.

19. A method for forming a material layer on a substrate, the method comprising: forming a seed layer on the substrate, the seed layer comprising a layer of a two-dimensional (2D) monolayer amorphous material having a disordered atomic structure that produces a strained 2D lattice of the layer of the 2D monolayer amorphous material and causes atomic rearrangement of the layer of the 2D monolayer amorphous material in three-dimensional (3D) space to produce localized electronic states to form potential wells for binding adatoms to a surface of the seed layer via van der Waals (vdW) interactions, wherein the potential wells each have a potential energy that is greater in magnitude than surrounding thermal energy to trap adatoms on the surface of the seed layer; and forming a layer of the material on the seed layer by bonding adatoms of the material to a surface of the seed layer via van der Waals (vdW) interactions, Wherein the layer of 2D single layer amorphous material comprises a homogeneous 2D single layer amorphous carbon.

20. The method of claim 19, further comprising changing the disordered atomic structure of the layer of the 2D monolayer amorphous material to adjust the strength of the vdW interaction between the adatoms of the material and the surface of the seed layer.

21. The method of claim 19 or 20, further comprising depositing one or more additional layers of a 2D single-layer amorphous carbon on the layer of the 2D single-layer amorphous material to form a seed layer of a multilayer structure before forming the material layer on the seed layer, so as to regulate the vdW interaction between the seed layer and the material layer and remotely regulate the interaction between the substrate and the adsorbed atoms to form the material layer during growth.

22. The method of claim 19 or claim 20, further comprising: forming an operating layer on the material layer; and The seed layer is released from the substrate to form a self-supporting film including the seed layer and the material layer.

23. The method of claim 19 or claim 20, wherein forming the seed layer on the substrate comprises growing the seed layer on the substrate using laser assisted chemical vapor deposition (LCVD).

24. The method of claim 23, wherein the laser assisted CVD is performed at a temperature between 20°C and 400°C.

25. A method for enhancing van der Waals (vdW) interactions between adatoms and a surface of a seed layer to form a material layer on the seed layer, the seed layer comprising a two-dimensional (2D) monolayer of amorphous material, the method comprising: forming a disordered atomic structure in the seed layer, the disordered atomic structure of the seed layer generating a strained 2D lattice of the seed layer and causing atomic rearrangement of the seed layer in three-dimensional (3D) space to generate localized electronic states to form potential wells for binding adatoms to the surface of the seed layer via vdW interactions to form the material layer, wherein the potential wells each have a potential energy that is greater in size than the surrounding thermal energy to trap adatoms on the surface of the seed layer, Wherein the layer of 2D single layer amorphous material comprises a homogeneous 2D single layer amorphous carbon.

26. The method of claim 25, wherein the seed layer comprises two or more layers of homogeneous 2D monolayer amorphous carbon and is formed on a substrate, the method further comprising varying the number of layers of the homogeneous 2D monolayer amorphous carbon to adjust the vdW interaction between the seed layer and the material layer and remotely adjusting the interaction between the substrate and the adsorbed atoms to form the material layer during growth.

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