TWI474966B - A method for making epitaxial structure - Google Patents

Description

Method for preparing epitaxial structure

The invention relates to a method for preparing an epitaxial structure.

Epitaxial structures, especially heteroepitaxial structures, are one of the main materials for fabricating semiconductor devices. For example, in recent years, gallium nitride epitaxial wafers for preparing light-emitting diodes (LEDs) have become a research hotspot.

The gallium nitride epitaxial wafer refers to a GaN material molecule which is regularly arranged and oriented on a sapphire substrate under certain conditions. However, the preparation of high-quality GaN epitaxial wafers has been a difficult point of research. Due to the difference in lattice constant and thermal expansion coefficient of the gallium nitride and sapphire substrates, there are many dislocation defects in the gallium nitride epitaxial layer. Moreover, there is a large stress between the gallium nitride epitaxial layer and the sapphire substrate, and the greater the stress, the GaN epitaxial layer is broken. This heteroepitaxial structure generally has a lattice mismatch phenomenon, and is easy to form defects such as misalignment.

The prior art provides a method for improving the above-described deficiencies by epitaxially growing gallium nitride using a non-flat sapphire substrate. However, the prior art generally forms a groove on the surface of the sapphire substrate by a microelectronic method such as photolithography to constitute a non-planar epitaxial growth surface. The method not only has a complicated manufacturing process, but also has high cost, and pollutes the epitaxial growth surface of the sapphire substrate, thereby affecting the quality of the epitaxial structure.

In summary, the invention provides a simple process, low cost, and does not make the surface of the substrate. The preparation of contaminated epitaxial structures is necessary.

A method for preparing an epitaxial structure, comprising the steps of: providing a substrate having an epitaxial growth surface; providing a first carbon nanotube layer on an epitaxial growth surface of the substrate; and an epitaxial growth surface of the substrate Growing a first epitaxial layer and covering the first carbon nanotube layer; and providing a second carbon nanotube layer on a surface of the first epitaxial layer, wherein a surface of the first epitaxial layer is the first An epitaxial growth surface of the epitaxial layer; and a second epitaxial layer is grown on the surface of the first epitaxial layer and covers the second carbon nanotube layer.

A method for preparing an epitaxial structure, comprising the steps of: providing a substrate, wherein the substrate has an epitaxial growth surface; providing a photomask layer on the epitaxial growth surface of the substrate; and growing the first epitaxial growth surface on the epitaxial growth surface of the substrate And covering the photomask layer; the surface of the first epitaxial layer is sequentially stacked to grow the second to n epitaxial layers, and at least one adjacent epitaxial layer is provided with a photomask layer; wherein n is an integer greater than or equal to 3. At least one of the photomask layers is a carbon nanotube layer.

Compared with the prior art, the method for obtaining a patterned photomask by providing a carbon nanotube layer on the epitaxial growth surface of the substrate is simple in process and low in cost, and the preparation cost of the epitaxial structure is greatly reduced, and the cost is reduced. Pollution to the environment. Further, the epitaxial structure including the carbon nanotube layer makes the epitaxial structure have a wide range of uses.

10,20,30‧‧‧ Epitaxial structures

100‧‧‧Base

101‧‧‧ Epitaxial growth surface

102‧‧‧First carbon nanotube layer

103‧‧‧First hole

104‧‧‧First epitaxial layer

105‧‧‧First opening

106‧‧‧ surface

107‧‧‧Second carbon nanotube layer

108‧‧‧second opening

109‧‧‧Second epilayer

1042‧‧‧ Epitaxial grains

1044‧‧‧ Epitaxial film

1092‧‧‧ Epitaxial grains

1093‧‧‧Second hole

1094‧‧‧ Epitaxial film

143‧‧‧Nano carbon nanotube fragments

145‧‧・Nano carbon tube

1 is a flow chart of a manufacturing method of a method for preparing an epitaxial structure according to an embodiment of the present invention.

2 is a scanning electron micrograph of a carbon nanotube film used in an embodiment of the present invention.

Fig. 3 is a schematic view showing the structure of a carbon nanotube segment in the carbon nanotube film of Fig. 2.

4 is a scanning electron micrograph of a carbon nanotube film disposed at a plurality of layers in an embodiment of the present invention.

Figure 5 is a scanning electron micrograph of a non-twisted nanocarbon pipeline used in an embodiment of the present invention.

Figure 6 is a scanning electron micrograph of a twisted nanocarbon line employed in an embodiment of the present invention.

FIG. 7 is a schematic diagram showing a growth process of a first epitaxial layer in an embodiment of the present invention.

Fig. 8 is a scanning electron micrograph of a cross section of an epitaxial structure prepared in accordance with a first embodiment of the present invention.

Fig. 9 is a transmission electron micrograph of the interface of the epitaxial structure prepared in the first embodiment of the present invention.

FIG. 10 is a schematic view showing a growth process of a second epitaxial layer according to an embodiment of the present invention.

FIG. 11 is a schematic perspective structural view of an epitaxial structure according to a first embodiment of the present invention.

Fig. 12 is a schematic cross-sectional view of the epitaxial structure shown in Fig. 11 taken along line XII-XII.

FIG. 13 is a schematic perspective structural view of an epitaxial structure according to a second embodiment of the present invention.

FIG. 14 is a schematic perspective structural view of an epitaxial structure according to a third embodiment of the present invention.

The epitaxial structure provided by the embodiment of the present invention and a preparation method thereof will be described in detail below with reference to the accompanying drawings. In order to facilitate understanding of the technical solution of the present invention, the present invention first introduces a method of preparing an epitaxial structure.

Referring to FIG. 1 , an embodiment of the present invention provides a method for preparing an epitaxial structure 10 . Specifically, the method includes the following steps: S10: providing a substrate 100, and the substrate 100 has an epitaxial growth surface 101 supporting the growth of the first epitaxial layer 104; S20: providing a first nanometer on the epitaxial growth surface 101 of the substrate 100 a carbon nanotube layer 102; S30: a first epitaxial layer 104 is grown on the epitaxial growth surface 101 of the substrate 100; S40: a second carbon nanotube layer 107 is disposed on the surface 106 of the first epitaxial layer 104; S50: The surface 106 of the first epitaxial layer 104 grows a second epitaxial layer 109.

In step S10, the substrate 100 provides an epitaxial growth surface 101 of the first epitaxial layer 104. The epitaxial growth surface 101 of the substrate 100 is a molecularly smooth surface, and impurities such as oxygen or carbon are removed. The substrate 100 can be a single layer or a plurality of layers. When the substrate 100 has a single layer structure, the substrate 100 may be a single crystal structure and have a crystal plane as the epitaxial growth surface 101 of the first epitaxial layer 104. The material of the single-layer structure substrate 100 may be GaAs, GaN, Si, SOI (silicon on insultor), AlN, SiC, MgO, ZnO, LiGaO ₂ , LiAlO ₂ or Al ₂ O ₃ or the like. When the substrate 100 has a plurality of layers, it is required to include at least one of the above single crystal structures, and the single crystal structure has a crystal plane as the epitaxial growth surface 101 of the first epitaxial layer 104. The material of the substrate 100 may be selected according to the first epitaxial layer 104 to be grown, preferably, the substrate 100 and the first epitaxial layer 104 have similar lattice constants and coefficients of thermal expansion. The thickness, size and shape of the substrate 100 are not limited and may be selected according to actual needs. The substrate 100 is not limited to the materials listed above, as long as the substrate 100 having the epitaxial growth surface 101 supporting the growth of the first epitaxial layer 104 is within the scope of the present invention.

In step S20, the first carbon nanotube layer 102 is a continuous overall structure including a plurality of carbon nanotubes. The plurality of carbon nanotubes in the first carbon nanotube layer 102 extend in a direction substantially parallel to the surface of the first carbon nanotube layer 102. When the first carbon nanotube layer 102 is disposed on the epitaxial growth surface 101 of the substrate 100, the extending direction of the plurality of carbon nanotubes in the first carbon nanotube layer 102 is substantially parallel to the substrate 100 Epitaxial growth surface 101. The first carbon nanotube layer 102 has a thickness of from 1 nm to 100 μm, or from 1 nm to 1 μm, or from 1 nm to 200 nm, preferably from 10 nm to 100 nm. The first carbon nanotube layer 102 can be a patterned carbon nanotube layer. The "patterning" means that the first carbon nanotube layer 102 has a plurality of first openings 105 penetrating the first opening 105 from the thickness direction of the first carbon nanotube layer 102. The carbon nanotube layer 102. When the first carbon nanotube layer 102 covers the epitaxial growth surface 101 of the substrate 100, the epitaxial growth surface 101 of the substrate 100 is exposed to the portion of the first opening 105 to facilitate growth. Epitaxial layer 104. The first opening 105 can be a micro hole or a gap. The size of the first opening 105 is 10 nm to 500 μm, and the size refers to the aperture of the micro hole or the pitch of the gap in the width direction. The first opening 105 has a size of 10 nm to 300 μm, or 10 nm to 120 μm, or 10 nm to 80 μm, or 10 nm to 10 μm. The smaller the size of the first opening 105, the less the generation of misalignment defects during the growth of the epitaxial layer is obtained to obtain the high quality first epitaxial layer 104. Preferably, the first opening 105 has a size of 10 nm to 10 μm. Further, the duty ratio of the first carbon nanotube layer 102 is 1:100~100:1, or 1:10~10:1, or 1:2~2:1, or 1:4~4 :1. Preferably, the duty ratio is 1:4~4:1. The "duty ratio" means that the first carbon nanotube layer 102 is disposed on the epitaxial growth surface 101 of the substrate 100, and the portion of the epitaxial growth surface 101 occupied by the first carbon nanotube layer 102 passes through the first opening. The area ratio of the exposed portion of 105.

Further, the "patterning" means that the arrangement of the plurality of carbon nanotubes in the first carbon nanotube layer 102 is ordered and regular. For example, the plurality of carbon nanotubes in the first carbon nanotube layer 102 have an axial direction substantially parallel to the epitaxial growth surface 101 of the substrate 100 and extend substantially in the same direction. Alternatively, the axial directions of the plurality of carbon nanotubes in the first carbon nanotube layer 102 may regularly extend substantially in more than two directions. Alternatively, the plurality of carbon nanotubes in the first carbon nanotube layer 102 extend axially along a crystal orientation of the substrate 100 or at an angle to a crystal orientation of the substrate 100. Adjacent carbon nanotubes extending in the same direction in the first carbon nanotube layer 102 are connected end to end by a van der Waals force.

On the premise that the first carbon nanotube layer 102 has the first opening 105 as described above, the plurality of carbon nanotubes in the first carbon nanotube layer 102 may also be disorderly arranged and randomly arranged. .

Preferably, the first carbon nanotube layer 102 is disposed on the entire epitaxial growth surface 101 of the substrate 100. The carbon nanotubes in the first carbon nanotube layer 102 may be one or a plurality of single-walled carbon nanotubes, double-walled carbon nanotubes or multi-walled carbon nanotubes, and the length and diameter thereof may be Choose as needed.

The first carbon nanotube layer 102 serves as a reticle for growing the first epitaxial layer 104. By "photomask" is meant that the first carbon nanotube layer 102 is used to shield a portion of the epitaxial growth surface 101 of the substrate 100 and expose a portion of the epitaxial growth surface 101 such that the first epitaxial layer 104 is only The exposed portion of the epitaxial growth surface 101 is grown. Since the first carbon nanotube layer 102 has a plurality of first openings 105, the first carbon nanotube layer 102 forms a patterned mask. After the first carbon nanotube layer 102 is disposed on the epitaxial growth surface 101 of the substrate 100, the plurality of carbon nanotubes extend in a direction parallel to the epitaxial growth surface 101. Since the first carbon nanotube layer 102 forms a plurality of first openings 105 on the epitaxial growth surface 101 of the substrate 100, the epitaxial growth surface 101 of the substrate 100 has a patterned mask. It can be understood that, compared with the microelectronic method such as photolithography, the method of epitaxial growth by providing the carbon nanotube layer 102 mask is simple in process, low in cost, and difficult to introduce pollution on the epitaxial growth surface 101 of the substrate 100, and is environmentally friendly. The production cost of the epitaxial structure 10 is greatly reduced.

It will be appreciated that the substrate 100 and the first nanotube layer 102 together form a substrate for growing the first epitaxial layer 104. The substrate can be used to grow a first epitaxial layer 104 of a different material, such as a semiconductor epitaxial layer, a metal epitaxial layer, or an alloy epitaxial layer. The substrate can also be used to grow a homoepitaxial layer.

The first carbon nanotube layer 102 may be directly formed on the epitaxial growth surface 101 of the substrate 100 after being formed. The first carbon nanotube layer 102 is a macroscopic structure, and the first carbon nanotube layer 102 is a self-supporting structure. By "self-supporting", it is meant that the first carbon nanotube layer 102 does not require a large area of carrier support, and that the first carbon nanotube layer 102 can be maintained by merely providing a supporting force on both sides to maintain its own state. When placed (or fixed) on two supports spaced apart by a certain distance, the first carbon nanotube layer 102 between the two supports can be suspended to maintain its own state. Since the first carbon nanotube layer 102 is of a self-supporting configuration, the first carbon nanotube layer 102 does not have to be formed on the epitaxial growth surface 101 of the substrate 100 by complicated chemical methods. Further preferably, the first carbon nanotube layer 102 is a pure carbon nanotube structure composed of a plurality of carbon nanotubes. By "pure carbon nanotube structure", it is meant that the carbon nanotube layer does not require any chemical modification or acidification treatment throughout the preparation process, and does not contain any functional group modification such as a carboxyl group.

The first carbon nanotube layer 102 can also be a plurality of carbon nanotubes and additives Composite structure of the material. The additive material includes one or a plurality of graphite, graphite thin, lanthanum carbide, boron nitride, tantalum nitride, cerium oxide, amorphous carbon, and the like. The additive material may further include one or a plurality of metal carbides, metal oxides, metal nitrides, and the like. The additive material is coated on at least a portion of the surface of the carbon nanotube layer 102 in the first carbon nanotube layer 102 or in the first opening 105 of the first carbon nanotube layer 102. Preferably, the additive material is coated on the surface of the carbon nanotube. Since the additive material is coated on the surface of the carbon nanotube, the diameter of the carbon nanotubes becomes large, so that the first opening 105 between the carbon nanotubes is reduced. The additive material may be formed on the surface of the carbon nanotube by chemical vapor deposition (CVD), physical vapor deposition (PVD), magnetron sputtering, or the like.

Laying the first carbon nanotube layer 102 on the epitaxial growth surface 101 of the substrate 100 may further include an organic solvent treatment step to make the first carbon nanotube layer 102 and the epitaxial growth surface 101 closer. Combine. The organic solvent may be selected from a mixture of one or more of ethanol, methanol, acetone, dichloroethane and chloroform. The organic solvent in this embodiment employs ethanol. The step of treating with an organic solvent may drip the organic solvent on the surface of the first carbon nanotube layer 102 through a test tube to infiltrate the entire first carbon nanotube layer 102 or the substrate 100 together with the entire first carbon nanotube layer 102. Immerse in a container filled with an organic solvent.

The first carbon nanotube layer 102 may also be directly grown on the epitaxial growth surface 101 of the substrate 100 or by the surface of the crucible substrate by chemical vapor deposition (CVD) or the like, and then transferred to the substrate 100. The epitaxial growth surface 101 is formed by directly depositing a solution containing a carbon nanotube on the epitaxial growth surface 101 of the substrate 100.

Specifically, the first carbon nanotube layer 102 may include a carbon nanotube film or a nano carbon line. The first carbon nanotube layer 102 can be a single layer of carbon nanotube film or a plurality of layers Stacked carbon nanotube membranes. The first carbon nanotube layer 102 may include a plurality of carbon nanotubes disposed in parallel or a plurality of carbon nanotubes disposed in an intersecting manner. When the first carbon nanotube layer 102 is a plurality of carbon nanotube films stacked, the number of layers of the carbon nanotube film is not too high, and preferably, it is 2 to 100 layers. When the first carbon nanotube layer 102 is a plurality of parallel carbon nanotubes, the distance between adjacent two nanocarbon lines is from 0.1 micrometer to 200 micrometers, preferably from 10 micrometers to 100 micrometers. A space between the adjacent two nanocarbon lines constitutes a first opening 105 of the first carbon nanotube layer 102. The length of the gap between two adjacent nanocarbon lines may be equal to the length of the nanocarbon line. The carbon nanotube film or the nanocarbon line may be directly laid on the epitaxial growth surface 101 of the substrate 100 to constitute the first carbon nanotube layer 102. The size of the first opening 105 in the first carbon nanotube layer 102 can be controlled by controlling the number of layers of the carbon nanotube film or the distance between the carbon nanotubes.

The carbon nanotube membrane is a self-supporting structure composed of a number of carbon nanotubes. The plurality of carbon nanotubes extend in a preferred orientation along the same direction. The preferred orientation means that the majority of the carbon nanotubes in the carbon nanotube film extend substantially in the same direction. Moreover, the overall direction of extension of the majority of the carbon nanotubes is substantially parallel to the surface of the carbon nanotube film. Further, the plurality of carbon nanotubes in the carbon nanotube film are connected end to end by van der Waals force. Specifically, each of the carbon nanotubes in the majority of the carbon nanotube membranes extending in the same direction and the carbon nanotubes adjacent in the extending direction are connected end to end by van der Waals force. Of course, there are a few randomly arranged carbon nanotubes in the carbon nanotube film, and these carbon nanotubes do not significantly affect the overall orientation of most of the carbon nanotubes in the carbon nanotube film. The self-supporting carbon nanotube film does not require a large-area carrier support, but can maintain a self-membrane state as long as the supporting force is provided on both sides, that is, the carbon nanotube film is placed (or fixed on) ) when the two supports are placed at a certain distance, the nano between the two supports The carbon tube film can be suspended to maintain its own membranous state. The self-supporting is mainly achieved by the presence of continuous carbon nanotubes extending through the end-to-end extension of the van der Waals force in the carbon nanotube film.

Specifically, the plurality of carbon nanotubes extending substantially in the same direction in the carbon nanotube film are not absolutely linear, and may be appropriately bent; or may not be completely aligned in the extending direction, and may be appropriately deviated from the extending direction. Therefore, it is not possible to exclude partial contact between the carbon nanotubes juxtaposed in the plurality of carbon nanotubes extending substantially in the same direction of the carbon nanotube film.

Referring to Figures 2 and 3, in particular, the carbon nanotube film comprises a plurality of continuous and oriented extended carbon nanotube segments 143. The plurality of carbon nanotube segments 143 are connected end to end by van der Waals force. Each of the carbon nanotube segments 143 includes a plurality of carbon nanotubes 145 that are parallel to each other, and the plurality of parallel carbon nanotubes 145 are tightly coupled by van der Waals force. The carbon nanotube segments 143 have any length, thickness, uniformity, and shape. The carbon nanotube film can be obtained by directly pulling a part of a carbon nanotube from an array of carbon nanotubes. The carbon nanotube film has a thickness of 1 nm to 100 μm, and the width is related to the size of the carbon nanotube array for taking out the carbon nanotube film, and the length is not limited. There are micropores or gaps between adjacent carbon nanotubes in the carbon nanotube film to constitute the first opening 105, and the pore size or gap size of the micropores is less than 10 micrometers. Preferably, the carbon nanotube film has a thickness of from 100 nm to 10 μm. The carbon nanotubes 145 in the carbon nanotube film extend in a preferred orientation in the same direction. For details of the carbon nanotube film and the preparation method thereof, please refer to the patent document "Nano Carbon Tube Film" of the Patent No. I327177, which was filed on February 12, 2010 by the applicant. Preparation". In order to save space, only the above is cited, but all the technical disclosures of the above application are also considered as part of the disclosure of the technology of the present application.

Referring to FIG. 4, when the carbon nanotube layer comprises a plurality of laminated carbon nanotube films stacked in a stack, the extending direction of the carbon nanotubes in the adjacent two layers of carbon nanotube film forms an intersection angle α, And α is greater than or equal to 0 degrees and less than or equal to 90 degrees (0° ≦ α ≦ 90 °).

In order to reduce the thickness of the carbon nanotube film, the carbon nanotube film may be further heat treated. In order to prevent the carbon nanotube film from being destroyed upon heating, the method of heating the carbon nanotube film adopts a local heating method. Specifically, the method comprises the steps of: locally heating the carbon nanotube film, so that a part of the carbon nanotube film is oxidized at a local position; and moving the carbon nanotube to be locally heated, from the local to the whole Heating of the carbon nanotube film. Specifically, the carbon nanotube film can be divided into a plurality of small regions, and the carbon nanotube film is heated region by region in a partial to overall manner. The method of locally heating the carbon nanotube film may be plural, such as laser heating, microwave heating, or the like. In this embodiment, the carbon nanotube film is irradiated by a laser scan having a power density of more than 0.1 × 10 ⁴ watts/m 2 , and the carbon nanotube film is heated from a partial to a whole. The carbon nanotube film is irradiated by laser, and some of the carbon nanotubes are oxidized in the thickness direction, and at the same time, the larger diameter carbon nanotube bundle in the carbon nanotube film is removed, so that the carbon nanotube film becomes thin.

It is to be understood that the above method of scanning the carbon nanotube film is not limited as long as the carbon nanotube film can be uniformly irradiated. The laser scanning can be performed row by row along the arrangement direction of the carbon nanotubes in the parallel carbon nanotube film, or can be performed column by column in the direction perpendicular to the arrangement of the carbon nanotubes in the carbon nanotube film. The smaller the speed of the laser-scanned carbon nanotube film with fixed power and fixed wavelength, the more heat absorbed by the carbon nanotube bundle in the carbon nanotube film, the more the corresponding carbon nanotube bundle is destroyed, after laser treatment The thickness of the carbon nanotube film becomes small. However, if the laser scanning speed is too small, the carbon nanotube film will absorb too much heat and be burned. In this embodiment, the laser power density is greater than 0.053×10 ¹² watts/square meter, the laser spot diameter is in the range of 1 mm to 5 mm, and the laser scanning illumination time is less than 1.8 seconds. Preferably, the laser is a carbon dioxide laser having a power of 30 watts, a wavelength of 10.6 microns, a spot diameter of 3 mm, and a relative movement speed of the laser device and the carbon nanotube film of less than 10 mm/sec. .

The nanocarbon line can be a non-twisted nanocarbon line or a twisted nanocarbon line. The non-twisted nanocarbon pipeline and the twisted nanocarbon pipeline are both self-supporting structures. Specifically, referring to FIG. 5, the non-twisted nanocarbon pipeline includes a plurality of carbon nanotubes extending in a direction parallel to the length of the non-twisted nanocarbon pipeline. Specifically, the non-twisted nanocarbon pipeline includes a plurality of carbon nanotube segments, and the plurality of carbon nanotube segments are connected end to end by a van der Waals force, and each of the carbon nanotube segments includes a plurality of parallel and pass through a van der Waals force. Tightly bonded carbon nanotubes. The carbon nanotube segments have any length, thickness, uniformity, and shape. The non-twisted nano carbon line is not limited in length and has a diameter of 0.5 nm to 100 μm. The non-twisted nano carbon pipeline is obtained by treating the carbon nanotube membrane with an organic solvent. Specifically, the organic solvent is used to impregnate the entire surface of the carbon nanotube film, and the mutually parallel complex carbon nanotubes in the carbon nanotube film pass through the surface tension generated by the volatilization of the volatile organic solvent. The wattage is tightly combined to shrink the carbon nanotube membrane into a non-twisted nanocarbon pipeline. The organic solvent is a volatile organic solvent such as ethanol, methanol, acetone, dichloroethane or chloroform, and ethanol is used in this embodiment. The non-twisted nanocarbon line treated by the organic solvent has a smaller specific surface area and a lower viscosity than the carbon nanotube film which is not treated with the organic solvent.

The twisted nanocarbon line is obtained by twisting both ends of the carbon nanotube film in opposite directions by a mechanical force. Referring to FIG. 6, the twisted nanocarbon pipeline includes a plurality of carbon nanotubes extending axially around the twisted nanocarbon pipeline. Specifically, the twist The converted nano carbon pipeline includes a plurality of carbon nanotube segments, and the plurality of carbon nanotube segments are connected end to end by van der Waals, and each carbon nanotube segment includes a plurality of carbon nanotubes which are parallel to each other and closely coupled by van der Waals force. Carbon tube. The carbon nanotube segments have any length, thickness, uniformity, and shape. The twisted nanocarbon line is not limited in length and has a diameter of 0.5 nm to 100 μm. Further, the twisted nanocarbon line can be treated with a volatile organic solvent. Under the action of the surface tension generated by the volatilization of the volatile organic solvent, the adjacent carbon nanotubes in the treated twisted nanocarbon pipeline are tightly bonded by van der Waals to make the specific surface area of the twisted nanocarbon pipeline Decrease, increase in density and strength.

For the nano carbon pipeline and the preparation method thereof, please refer to the patent of the Republic of China, No. I303239, filed on November 5, 2008, filed by the applicant on November 5, 2002, the applicant: Hon Hai Precision Industry Co., Ltd. And the application of the Republic of China patent No. I312337, which was filed on December 16, 2005, was filed on July 21, 2009. Applicant: Hon Hai Precision Industry Co., Ltd.

The carbon nanotube film can also be formed by the following steps: a, placing a substrate at the bottom of a beaker; b, dispersing the prepared single-walled carbon nanotube tube in a solvent in another beaker, and ultrasonically shaking for ten minutes. Left and right, remove the precipitate and obtain a solution floating on the surface layer, and then pour the solution floating on the surface layer into a beaker provided with a substrate; c, heat the beaker to evaporate the solvent, so that the carbon carbon nanotube tube is uniformly deposited on the substrate Upper, thereby forming a carbon carbon nanotube film on the surface of the substrate. In addition, the carbon nanotube film obtained by the method has a non-directional arrangement of carbon nanotubes. It will be appreciated that the carbon nanotube film can be formed by other methods such as electrophoresis or precipitation.

In step S30, the growth method of the first epitaxial layer 104 may be performed by molecular beam epitaxy (MBE), chemical beam epitaxy (CBE), reduced pressure epitaxy, low temperature epitaxy, Selective epitaxy, liquid phase deposition epitaxy (LPE), metal organic vapor phase epitaxy (MOVPE), ultra-vacuum chemical vapor deposition (UHVCVD), hydride vapor phase epitaxy (HVPE), and metal organic chemical vapor phase One or a plurality of implementations of deposition methods (MOCVD) and the like.

The first epitaxial layer 104 refers to a single crystal structure grown by epitaxial growth on the epitaxial growth surface 101 of the substrate 100, and the material thereof is different from the substrate 100, so it may also be referred to as a heteroepitaxial layer. The thickness of the growth of the first epitaxial layer 104 can be prepared as needed. Specifically, the first epitaxial layer 104 may have a growth thickness of 0.5 nm to 1 mm. For example, the first epitaxial layer 104 may have a thickness of from 100 nanometers to 500 micrometers, or from 200 nanometers to 200 micrometers, or from 500 nanometers to 100 micrometers. The first epitaxial layer 104 may be a semiconductor epitaxial layer, and the material of the semiconductor epitaxial layer is GaMnAs, GaAlAs, GaInAs, GaAs, SiGe, InP, Si, AlN, GaN, GaInN, AlInN, GaAlN or AlGaInN. The first epitaxial layer 104 can be a metal epitaxial layer, and the metal epitaxial layer is made of aluminum, platinum, copper or silver. The first epitaxial layer 104 may be an alloy epitaxial layer, and the material of the epitaxial layer of the alloy is MnGa, CoMnGa or Co ₂ MnGa.

Referring to FIG. 7 , specifically, the growth process of the first epitaxial layer 104 specifically includes the following steps: S31 : nucleating and epitaxially growing along the epitaxial growth surface 101 substantially perpendicular to the substrate 100 to form a plurality of epitaxial grains 1042: S32: the plurality of epitaxial grains 1042 are epitaxially grown along a direction substantially parallel to the epitaxial growth surface 101 of the substrate 100 to form a continuous epitaxial film 1044; S33: the epitaxial film 1044 is substantially perpendicular to the Epitaxial growth of substrate 100 Epitaxial growth in the direction of the face 101 forms a first epitaxial layer 104.

In step S31, the plurality of epitaxial grains 1042 are grown on a portion of the epitaxial growth surface 101 of the substrate 100 exposed through the first opening 105 of the first carbon nanotube layer 102, and the growth direction thereof is substantially perpendicular to The epitaxial growth surface 101 of the substrate 100, that is, the plurality of epitaxial grains 1042 in this step is longitudinally epitaxially grown.

In step S32, the plurality of epitaxial grains 1042 are homogenously epitaxially grown and integrated in a direction substantially parallel to the epitaxial growth surface 101 of the substrate 100 by controlling growth conditions to integrate the first carbon nanotube layer 102. cover. That is, the plurality of epitaxial grains 1042 are directly closed in the lateral epitaxial growth in this step, and finally a plurality of first holes 103 are formed around the carbon nanotubes to surround the carbon nanotubes. Preferably, the carbon nanotubes are spaced apart from the first epitaxial layer 104 surrounding the carbon nanotubes. The shape of the holes is related to the arrangement direction of the carbon nanotubes in the first carbon nanotube layer 102. When the first carbon nanotube layer 102 is a single-layer carbon nanotube film or a plurality of parallel disposed nano carbon lines, the plurality of first holes 103 are substantially parallel grooves. When the first carbon nanotube layer 102 is a plurality of layers of carbon nanotube film or a plurality of interdigitated carbon nanotubes, the plurality of first holes 103 are intersecting groove networks.

In step S33, due to the presence of the first carbon nanotube layer 102, lattice dislocations between the epitaxial grains 1042 and the substrate 100 stop growing during the formation of the continuous epitaxial film 1044. Therefore, the first epitaxial layer 104 of this step is equivalent to homoepitaxial growth on the surface of the epitaxial film 1044 having no defects. The first epitaxial layer 104 has fewer defects.

In the first embodiment of the present invention, the substrate 100 is a sapphire (Al ₂ O ₃ ) substrate, and the first carbon nanotube layer 102 is a single-layer carbon nanotube film. This embodiment uses epitaxial growth by MOCVD. Among them, high-purity ammonia (NH ₃ ) is used as the source gas of nitrogen, hydrogen (H ₂ ) is used as the carrier gas, and trimethylgallium (TMGa) or triethylgallium (TEGa) or trimethylindium (TMIn) is used. And trimethylaluminum (TMAl) as a Ga source, an In source, and an Al source. Specifically, the method includes the following steps: First, the sapphire substrate 100 is placed in a reaction chamber, heated to 1100 ° C to 1200 ° C, and H ₂ , N ₂ or a mixed gas thereof is introduced as a carrier gas, and baked at a high temperature for 200 seconds to 1000 seconds.

Secondly, continue to pass the carrier gas, and cool down to 500 ° C ~ 650 ° C, through the introduction of trimethyl gallium or triethyl gallium and ammonia, grow GaN low temperature buffer layer, the thickness of 10 nm ~ 50 nm.

Then, the passage of trimethylgallium or triethylgallium is stopped, and the ammonia gas and the carrier gas are continuously supplied, and the temperature is raised to 1100 ° C to 1200 ° C, and the temperature is maintained for 30 seconds to 300 seconds for annealing.

Finally, the temperature of the substrate 100 is maintained at 1000 ° C ~ 1100 ° C, and the ammonia gas and the carrier gas are continuously introduced, and trimethylgallium or triethylgallium is re-introduced, and the lateral epitaxial growth process of GaN is completed at a high temperature. And a high quality GaN epitaxial layer is grown.

After the sample was grown, the samples were observed and tested by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. Referring to FIG. 8 and FIG. 9, in the epitaxial structure prepared in this embodiment, the first epitaxial layer is grown only from the position where the epitaxial growth surface of the substrate has no carbon nanotube layer, and then integrated. The surface of the first epitaxial layer in contact with the substrate forms a plurality of holes, and the carbon nanotube layer is disposed in the hole and spaced apart from the first epitaxial layer. Since the shape of the pore is related to the arrangement direction of the carbon nanotubes in the carbon nanotube layer, the plurality of pores are distributed in a plane in communication with each other. Preferably, the plurality of holes are nano-scale holes. Specifically, it can be clearly seen from FIG. 8 that the interface between the GaN epitaxial layer and the sapphire substrate is seen, wherein The color portion is a GaN epitaxial layer, and the light portion is a sapphire substrate. The surface of the GaN epitaxial layer in contact with the sapphire substrate has a row of holes. As can be seen from Fig. 9, a carbon nanotube is disposed in each of the holes. The carbon nanotubes in the holes are disposed on the surface of the sapphire substrate and spaced apart from the GaN epitaxial layer forming the holes.

In the step S40, the structure, the arrangement, the forming method, the material and the like of the second carbon nanotube layer 107 are the same as those of the first carbon nanotube layer 102, and therefore will not be described herein.

The second carbon nanotube layer 107 has a plurality of second openings 108 penetrating the second carbon nanotube layer 107 from the thickness direction of the second carbon nanotube layer 107. When the second carbon nanotube layer 107 covers the surface 106 of the first epitaxial layer 104, the surface 106 of the first epitaxial layer 104 is exposed to the portion of the second opening 108 for growth. Two epitaxial layers 109. The second opening 108 can be a micro hole or a gap. The second opening 108 is sized and distributed in the same manner as the first opening 105.

In the step S50, the second epitaxial layer 109 refers to a single crystal structure grown on the surface 106 of the first epitaxial layer 104 by epitaxial method, and the material thereof may be the same as or different from the material of the first epitaxial layer 104. . The growth method and material of the second epitaxial layer 109 may adopt the growth method and material of the first epitaxial layer 104 in step S20.

Referring to FIG. 10, in particular, the growth process of the second epitaxial layer 109 specifically includes the following steps: S51: nucleating along a direction substantially perpendicular to the surface 106 of the first epitaxial layer 104 away from the substrate 100 and Epitaxially growing to form a plurality of epitaxial grains 1092; S52: the plurality of epitaxial grains 1092 are substantially parallel to the first epitaxial layer 104 Epitaxially growing from the surface 106 of the substrate 100 to form a continuous epitaxial film 1094; S53: the epitaxial film 1094 is epitaxially grown along a direction substantially perpendicular to the surface 106 of the first epitaxial layer 104 remote from the substrate 100. A second epitaxial layer 109 is formed.

In step S51, the plurality of epitaxial grains 1092 start to grow at a portion of the first epitaxial layer 104 that is away from the surface 106 of the substrate 100 through the second opening 108 of the second carbon nanotube layer 107. And the growth direction thereof is substantially perpendicular to the surface 106 of the first epitaxial layer 104 away from the substrate 100, that is, the plurality of epitaxial grains 1092 are longitudinally epitaxially grown in this step.

In step S52, the plurality of epitaxial grains 1092 are homogenously epitaxially grown and integrated in a direction substantially parallel to the surface 106 of the first epitaxial layer 104 away from the substrate 100 by controlling growth conditions. The carbon nanotube layer 107 is covered. That is, in the step, the plurality of epitaxial grains 1092 undergo direct lateral epitaxial growth, and finally a plurality of second holes 1093 are formed around the carbon nanotubes to surround the carbon nanotubes. Preferably, the carbon nanotubes are spaced apart from the second epitaxial layer 109 surrounding the carbon nanotubes. The shape of the holes is related to the arrangement direction of the carbon nanotubes in the second carbon nanotube layer 107. When the second carbon nanotube layer 107 is a single-layer carbon nanotube film or a plurality of parallel carbon nanotubes, the plurality of second holes 1093 are substantially parallel grooves. When the second carbon nanotube layer 107 is a plurality of layers of carbon nanotube film or a plurality of interdigitated carbon nanotubes, the plurality of second holes 1093 are intersecting groove networks.

In step S53, due to the presence of the second carbon nanotube layer 107, lattice dislocations between the epitaxial grains 1092 and the substrate 100 stop growing during the formation of the continuous epitaxial film 1094. Therefore, the second epitaxial layer 109 of this step is equivalent to no shortage The surface of the depressed epitaxial film 1094 is subjected to homoepitaxial growth. The second epitaxial layer 109 has fewer defects.

In the first embodiment of the present invention, the second carbon nanotube layer 107 is a single-layer carbon nanotube film. In this embodiment, the second epitaxial layer 109 is epitaxially grown by the MOCVD method. Among them, high-purity ammonia (NH3) is used as the source gas of nitrogen, hydrogen (H2) is used as the carrier gas, and trimethylgallium (TMGa) or triethylgallium (TEGa) or trimethylindium (TMIn) is used. Trimethylaluminum (TMAl) is used as a Ga source, an In source, and an Al source. Specifically, the method includes the following steps: First, the substrate 100 on which the first epitaxial layer 104 is grown is placed in a reaction chamber, heated to 1100 ° C to 1200 ° C, and H ₂ , N ₂ or a mixed gas thereof is introduced as a carrier gas, and baked at a high temperature. 200 seconds to 1000 seconds.

Secondly, continue to carry the same carrier gas, and cool down to 500 ° C ~ 650 ° C, through the introduction of trimethyl gallium or triethyl gallium and ammonia, grow GaN low temperature buffer layer, the thickness of 10 nm ~ 50 nm.

Then, the passage of trimethylgallium or triethylgallium is stopped, and the ammonia gas and the carrier gas are continuously supplied, and the temperature is raised to 1100 ° C to 1200 ° C, and the temperature is maintained for 30 seconds to 300 seconds for annealing.

Finally, the temperature of the substrate 100 on which the first epitaxial layer 104 is grown is maintained at 1000 ° C to 1100 ° C, and the ammonia gas and the carrier gas are continuously introduced, and the trimethyl gallium or triethyl gallium is re-introduced at a high temperature. The lateral epitaxial growth process of GaN and the growth of a higher quality GaN epitaxial layer.

Referring to FIG. 11 and FIG. 12, an epitaxial structure 10 prepared by the first embodiment of the present invention includes: a substrate 100, a first carbon nanotube layer 102, a first epitaxial layer 104, and a first The carbon nanotube layer 107 and the second epitaxial layer 109. The substrate 100 has an epitaxial growth surface 101. The first carbon nanotube layer 102 is disposed on the epitaxial growth surface 101 of the substrate 100. The first carbon nanotube layer 102 has a plurality of first openings 105, and the epitaxial growth surface 101 of the substrate 100 corresponds to the A portion of the first opening 105 of the first carbon nanotube layer 102 is exposed. The first epitaxial layer 104 is disposed on the epitaxial growth surface 101 of the substrate 100 and covers the first carbon nanotube layer 102. The first carbon nanotube layer 102 is disposed between the first epitaxial layer 104 and the substrate 100. The second carbon nanotube layer 107 is disposed on the surface 106 of the first epitaxial layer 104 away from the substrate 100. The second carbon nanotube layer 107 has a plurality of second openings 108, and the first epitaxial layer 104 The surface 106 remote from the substrate 100 is exposed to a portion of the second opening 108 of the second carbon nanotube layer 107. The second epitaxial layer 109 is disposed on the surface 106 of the first epitaxial layer 104 away from the substrate 100 and covers the second carbon nanotube layer 107. The second carbon nanotube layer 107 is located between the second epitaxial layer 109 and the first epitaxial layer 104.

The first epitaxial layer 104 covers the first carbon nanotube layer 102, and penetrates the plurality of first openings 105 of the first carbon nanotube layer 102 to contact the epitaxial growth surface 101 of the substrate 100, That is, the first epitaxial layer 104 is infiltrated into the plurality of first openings 105 of the first carbon nanotube layer 102. The first epitaxial layer 104 is microscopically spaced from the first carbon nanotube layer 102 covered by the first epitaxial layer 104, that is, the surface of the first epitaxial layer 104 in contact with the substrate 100 forms a plurality of first holes 103, the first nai The carbon nanotube layer 102 is disposed in the first hole 103. Specifically, the carbon nanotubes in the first carbon nanotube layer 102 are respectively disposed in the plurality of first holes 103. The first hole 103 is formed on a surface of the first epitaxial layer 104 that is in contact with the substrate 100. The first holes 103 are blind holes in the thickness direction of the first epitaxial layer 104. Within each of the first holes 103, the carbon nanotubes are substantially not in contact with the first epitaxial layer 104.

The second epitaxial layer 109 covers the second carbon nanotube layer 107 and penetrates the plurality of second openings 108 of the second carbon nanotube layer 107 and the first epitaxial layer 104 away from the substrate 100 The surface 106 is in contact with the second epitaxial layer 109 in the plurality of second openings 108 of the second carbon nanotube layer 107. The second epitaxial layer 109 is microscopically spaced from the second carbon nanotube layer 107 covered by the second epitaxial layer 109, that is, the surface of the second epitaxial layer 109 contacting the first epitaxial layer 104 forms a plurality of second holes 1093. The second carbon nanotube layer 107 is disposed in the second hole 1093. Specifically, the carbon nanotubes in the second carbon nanotube layer 107 are respectively disposed in the plurality of second holes 1093. The second hole 1093 is formed on a surface of the second epitaxial layer 109 that is in contact with the first epitaxial layer 104. The second hole 1093 is a blind hole in a thickness direction of the first epitaxial layer 104. Within each of the second holes 1093, the carbon nanotubes are substantially not in contact with the second epitaxial layer 109.

The first carbon nanotube layer 102 and the second carbon nanotube layer 107 are both self-supporting structures. The carbon nanotube layer comprises a carbon nanotube membrane or a nanocarbon pipeline. In this embodiment, the first carbon nanotube layer 102 and the second carbon nanotube layer 107 are respectively a single-layer carbon nanotube film, and the carbon nanotube film comprises a plurality of carbon nanotubes. The axial direction of the plurality of carbon nanotubes extends in a preferred orientation in the same direction, and adjacent carbon nanotubes extending in the same direction are connected end to end by van der Waals force. Micropores or gaps are provided at intervals between adjacent carbon nanotubes perpendicular to the extending direction to constitute a first opening 105 and a second opening 108.

Referring to FIG. 13, an epitaxial structure 20 prepared according to a second embodiment of the present invention includes: a substrate 100, a first carbon nanotube layer 102, a first epitaxial layer 104, and a second nanometer. The carbon tube layer 107 and a second epitaxial layer 109. The material of the first epitaxial layer 104 and the second epitaxial layer 109 of the epitaxial structure 20 in the second embodiment of the present invention The positional relationship of the substrate 100, the first carbon nanotube layer 102, the first epitaxial layer 104, the second carbon nanotube layer 107, and the second epitaxial layer 109 is substantially the same as that of the epitaxial structure 10 of the first embodiment. The difference is that the first carbon nanotube layer 102 and the second carbon nanotube layer 107 are respectively composed of a plurality of parallel and spaced carbon nanotube lines, and micropores are formed between adjacent nano carbon lines.

The nanocarbon line can be a non-twisted nanocarbon line or a twisted nanocarbon line. Specifically, the non-twisted nanocarbon pipeline includes a plurality of carbon nanotubes extending along the length of the non-twisted nanocarbon pipeline. The twisted nanocarbon pipeline includes a plurality of carbon nanotubes extending axially around the twisted nanocarbon pipeline.

In addition, in the embodiment, the substrate 100 is a silicon-on-insulator (SOI) substrate. The first epitaxial layer 104 of this embodiment is epitaxially grown by the MOCVD method. Among them, trimethylgallium (TMGa) and trimethylaluminum (TMAl) are used as the source materials of Ga and Al, ammonia (NH ₃ ) is used as the source of nitrogen, and hydrogen (H 2 ) is used as the carrier gas. The leveling furnace is heated. Specifically, a plurality of parallel and spaced carbon nanotube lines are first laid on the epitaxial growth surface 101 of the SOI substrate 100. Then, a GaN epitaxial layer is epitaxially grown on the epitaxial growth surface 101 of the substrate 100, and the growth temperature is 1070 ° C, and the growth time is 450 seconds, mainly for longitudinal growth of GaN; then, the pressure of the reaction chamber is kept constant, and the temperature is raised to 1110 ° C while decreasing. The Ga source flow rate while maintaining the ammonia flow rate constant to promote lateral epitaxial growth with a growth time of 4900 seconds; finally, the temperature was lowered to 1070 ° C while increasing the Ga source flow rate and continuing longitudinal growth for 10,000 seconds.

Referring to FIG. 14 , a third embodiment of the present invention provides an epitaxial structure 30 including a substrate 100 , a first carbon nanotube layer 102 , a first epitaxial layer 104 , and a second carbon nanotube layer . 107 and a second epitaxial layer 109. In the third embodiment of the present invention The substrate 100 of the epitaxial structure 30, the material of the first epitaxial layer 104 and the second epitaxial layer 109, and the substrate 100, the first carbon nanotube layer 102, the first epitaxial layer 104, and the second carbon nanotube layer 107 are The positional relationship of the second epitaxial layer 109 is substantially the same as that of the epitaxial structure 10 of the first embodiment, except that the first carbon nanotube layer 102 and the second carbon nanotube layer 107 are each crossed and spaced apart. The nano carbon line is formed by forming micropores between the four nano carbon lines that are crossed and adjacent. Specifically, the plurality of carbon carbon pipelines are respectively disposed in parallel with the second direction along the first direction, and the first direction is disposed to intersect with the second direction. An opening is formed between the four nano carbon lines that are crossed and adjacent. In this embodiment, two adjacent nanocarbon pipelines are arranged in parallel, and the two nanocarbon pipelines intersecting each other are perpendicular to each other. It can be understood that the nano carbon pipeline can also be disposed in any intersection manner, and only the first carbon nanotube layer 102 and the second carbon nanotube layer 107 are respectively formed into a plurality of openings, thereby making the substrate 100 and the first epitaxy. The epitaxial growth surface of layer 104 may be partially exposed.

The epitaxial structure 30 of the third embodiment of the present invention can be produced by the same method as the first embodiment or the second embodiment.

A fourth embodiment of the present invention provides a complex layer epitaxial structure comprising: a substrate, a plurality of carbon nanotube layers, and a plurality of epitaxial layers. The carbon nanotube layer in the fourth embodiment of the present invention may adopt the carbon nanotube layer of the first to third embodiments, the material and the positional relationship between the substrate, the carbon nanotube layer and the epitaxial layer, and the first The embodiments are basically the same, except that the epitaxial structure of the present embodiment includes a plurality of stacked epitaxial layers, and a carbon nanotube layer is disposed between the epitaxial growth surface of the substrate and each adjacent epitaxial layer.

The fourth embodiment of the present invention further provides a method for preparing a plurality of layers of epitaxial structures, which specifically includes the following steps: The first step: providing a substrate, the substrate has an epitaxial growth surface supporting the epitaxial layer growth; and the second step: providing a carbon nanotube layer on the epitaxial growth surface of the substrate, the substrate and the carbon nanotube layer Forming a substrate together; a third step: growing a first epitaxial layer on the epitaxial growth surface of the substrate; a fourth step: providing a carbon nanotube layer on the surface of the first epitaxial layer; and a fifth step: in the first epitaxial layer Surface growth of the second epitaxial layer; sixth step: providing a carbon nanotube layer on the surface of the second epitaxial layer away from the first epitaxial layer; and seventh step: growing on the surface of the second epitaxial layer away from the first epitaxial layer 3 epitaxial layer; ... S step: providing a carbon nanotube layer on the surface of the nth epitaxial layer away from the epitaxial layer n-1; Step S+1: away from the epitaxial layer n- in the nth epitaxial layer The n+1th epitaxial layer was grown on the surface of 1.

Wherein S is an integer greater than or equal to 8, and n is an integer greater than or equal to 3.

The method of growing each epitaxial layer of the fourth embodiment of the present invention is substantially the same as the method of growing the epitaxial layer of the first embodiment.

It can be understood that the second to n-th epitaxial layers are sequentially stacked and grown on the surface of the first epitaxial layer, and a photomask layer is disposed between each adjacent epitaxial layer, and at least one photomask layer in the photomask layer is nanocarbon. Pipe layer. When the nth epitaxial layer is grown, the surface of the n-1th epitaxial layer away from the n-2th epitaxial layer may be provided with, for example, a patterned SiO ₂ or the like in addition to a carbon nanotube layer. Mask layer.

The invention adopts a carbon nanotube layer as a photomask disposed on the epitaxial growth surface growth epitaxial layer of the substrate to have the following effects:

First, the carbon nanotube layer is a self-supporting structure, and can be directly laid on the epitaxial growth surface of the substrate, and the photomask is formed by a manufacturing method such as post-deposition lithography, which is simple in process and low in cost. Conducive to mass production.

Secondly, the carbon nanotube layer is a patterned structure, and the thickness and the opening size thereof can reach a nanometer level, and the epitaxial grains formed when the substrate is used to grow the epitaxial layer have a smaller size, which is advantageous for Reduce the generation of dislocation defects to obtain a high quality epitaxial layer.

Third, the carbon nanotube layer has an opening size up to the nanometer scale, and the epitaxial layer is grown from the exposed epitaxial growth surface corresponding to the nanometer opening, such that the contact area between the grown epitaxial layer and the substrate The reduction and the stress between the epitaxial layer and the substrate during the growth process are reduced, so that the epitaxial layer having a larger thickness can be grown, and the quality of the epitaxial layer can be further improved.

Fourth, by setting the carbon nanotube film multiple times and epitaxially growing the epitaxial layer multiple times, defects in the epitaxial layer can be further reduced, and the quality of the epitaxial layer can be improved.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by those skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

10‧‧‧ Epitaxial structures

100‧‧‧Base

101‧‧‧ Epitaxial growth surface

102‧‧‧First carbon nanotube layer

103‧‧‧First hole

104‧‧‧First epitaxial layer

105‧‧‧First opening

106‧‧‧ surface

107‧‧‧Second carbon nanotube layer

108‧‧‧second opening

109‧‧‧Second epilayer

1093‧‧‧Second hole

Claims (12)

A method for preparing an epitaxial structure, comprising the steps of: providing a substrate having an epitaxial growth surface; providing a first carbon nanotube layer on an epitaxial growth surface of the substrate; and an epitaxial growth surface of the substrate Growing a first epitaxial layer and covering the first carbon nanotube layer; and providing a second carbon nanotube layer on a surface of the first epitaxial layer, wherein a surface of the first epitaxial layer is the first An epitaxial growth surface of the epitaxial layer; and a second epitaxial layer is grown on the surface of the first epitaxial layer and covers the second carbon nanotube layer; wherein the first and second carbon nanotube layers Each is a continuous unitary structure comprising a plurality of carbon nanotubes, and the plurality of carbon nanotubes extend in a direction parallel to the surfaces of the first and second carbon nanotube layers, respectively. The method for preparing an extended structure according to claim 1, wherein the first epitaxial layer is a heteroepitaxial layer. The method for preparing an outer structure according to the first aspect of the invention, wherein the substrate is a single crystal structure, and the material of the substrate is GaAs, GaN, Si, SOI, AlN, SiC, MgO, ZnO, LiGaO ₂ , LiAlO ₂ or Al ₂ O ₃ . The method for preparing an outer structure according to the first aspect of the invention, wherein the method of disposing a carbon nanotube layer on an epitaxial growth surface of the substrate or a surface of the first epitaxial layer is a carbon nanotube The film or nano carbon line is directly laid on the epitaxial growth surface of the substrate as a carbon nanotube layer. The method for preparing an outer structure according to the first aspect of the invention, wherein the nano carbon The tube layer has a plurality of openings therein, and the first epitaxial layer or the second epitaxial layer is grown from a portion of the epitaxial growth surface exposed through the opening. The method for preparing an outer structure according to the first aspect of the invention, wherein the method for growing the first epitaxial layer or the second epitaxial layer comprises the following steps: forming a direction substantially perpendicular to the epitaxial growth surface And epitaxially growing to form a plurality of epitaxial grains; the plurality of epitaxial grains are epitaxially grown substantially parallel to the epitaxial growth surface to form a continuous epitaxial film; and the epitaxial film is substantially perpendicular to the epitaxial Epitaxial growth in the growth plane direction forms an epitaxial layer. The method for preparing an outer structure according to the first aspect of the invention, wherein the method for growing the first or second epitaxial layer comprises a molecular beam epitaxy method, a chemical beam epitaxy method, a vacuum deuteration method, and a low temperature epitaxy method. One or more of an epitaxial method, a liquid phase deposition epitaxy method, a metal organic vapor phase epitaxy method, an ultra-vacuum chemical vapor deposition method, a hydride vapor phase epitaxy method, and a metal organic chemical vapor deposition method. The method for preparing an outer structure according to claim 6, wherein the first or second epitaxial layer forms a plurality of holes around the second carbon nanotube layer to form the carbon nanotube layer. Surrounded by carbon nanotubes in the middle. The method for preparing an extended structure according to claim 1, wherein the first epitaxial layer or the second epitaxial layer is a homoepitaxial layer. The method for preparing an outer structure according to the first aspect of the invention, wherein the carbon nanotube layer is a self-supporting structure. The method for preparing an outer structure according to the first aspect of the invention, wherein the placing the carbon nanotube layer on the epitaxial growth surface further comprises treating the carbon nanotube layer with an organic solvent to make a nanometer The carbon tube layer is more closely attached to the epitaxial growth surface. A method for preparing an epitaxial structure, comprising the steps of: providing a substrate, wherein the substrate has an epitaxial growth surface; providing a photomask layer on the epitaxial growth surface of the substrate; and forming an epitaxial growth surface on the substrate Growing a first epitaxial layer and covering the photomask layer; sequentially forming a second to n epitaxial layer on the surface of the first epitaxial layer, and each adjacent epitaxial layer in the second to n epitaxial layers A photomask layer is disposed therebetween; wherein n is an integer greater than or equal to 3, at least one photomask layer in the photomask layer is a carbon nanotube layer; wherein the carbon nanotube layer comprises a plurality of nanometer tubes A continuous overall configuration of the carbon tubes, and the plurality of carbon nanotubes extend in a direction parallel to the surface of the carbon nanotube layer, respectively.