A method for laser-induced in-situ growth of periodic nanostructures

Abstract

The application discloses a method for laser-induced in-situ growth of periodic nanostructure, comprising the following steps: step one: first growth is carried out on a substrate to form a buffer layer, and the surface of the substrate is flattened; and step two: while a plurality of laser beams are used to irradiate the substrate, the substrate is continuously grown, wherein the plurality of laser beams form interference on the substrate, and the periodic nanostructure is formed after the continuous growth for 1-4 hours. The laser interference is used to induce in-situ growth on the substrate, so that the complex processes such as photoetching, etching and cleaning are avoided, and the cost is reduced. The laser interference is used to induce positioning growth, so that the positioning is more accurate, and the accuracy is higher. Meanwhile, the opening cavity operation is avoided, so that the subsequent structure growth is not polluted, and the structure performance is better.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic materials, and more specifically, to a method for laser-induced in-situ growth of periodic nanostructures. Background Technology

[0002] Periodic nanostructures are a group of nanomaterials composed of single or multiple nanounits / components arranged periodically into ordered patterns (such as vertical and lateral superlattices). Due to their unique physicochemical properties, they have enormous application potential in energy conversion, electronics, and optoelectronics. Among them, two-dimensional photonic crystals, Bragg mirrors, and other nanostructures are widely used to enhance the luminescence efficiency, absorption efficiency, and Raman effect of materials.

[0003] Currently, the main methods for preparing periodic nanostructures include photolithography, electron beam lithography, nanoimprinting, and focused ion beam etching. However, these methods are not only complex to operate and have low yields, but also have low processing precision and high costs, which restricts their development.

[0004] Therefore, a high-precision, low-cost, and efficient method for preparing periodic nanostructures is needed to solve the above problems. Summary of the Invention

[0005] One object of the present invention is to provide a new technical solution for the growth of periodic nanostructures.

[0006] According to a first aspect of the present invention, a method for laser-induced in-situ growth of periodic nanostructures is provided, comprising the following steps:

[0007] Step 1: Perform the first growth on the substrate to form a buffer layer and smooth the substrate surface;

[0008] Step 2: Continue growth on the substrate while being irradiated with multiple laser beams. The multiple laser beams interfere with each other on the substrate. After 1-4 hours of continued growth, a periodic nanostructure is formed.

[0009] Preferably, the substrate includes, but is not limited to, one of GaAs, InP, Al2O3 or GaSb; in the initial growth, the material forming the buffer layer includes, but is not limited to, one of GaAs, InP, GaSb, GaN, SiC, InAs or GaP; and in the continued growth, the material forming the periodic nanostructure includes, but is not limited to, one of GaAs, InP, GaSb, GaN, SiC, InAs or GaP.

[0010] Preferably, in step two, the substrate temperature is controlled at 0-200°C for continued growth.

[0011] Preferably, in step two, the multiple laser beams are formed by using one laser beam to irradiate the beam splitter to form two laser beams, and the two laser beams are respectively irradiated onto the substrate through a reflector to form interference.

[0012] Preferably, in step two, the wavelength of the laser beam is 320-488nm; the pulse width of the laser beam is 2-1000ns; and the average power of the laser beam is 40-100mW.

[0013] Preferably, the angle between the laser beam and the substrate perpendicular to the direction is 40-70 degrees.

[0014] Preferably, the initial growth and subsequent growth are performed using molecular beam epitaxy or vapor phase epitaxy.

[0015] Preferably, in step one, the surface oxide of the substrate is first removed before the first growth is performed.

[0016] Preferably, in step one, after the buffer layer is grown for the first time, the lower confinement layer and the active region are grown before proceeding to step two.

[0017] According to one embodiment of this disclosure, laser interference-induced in-situ growth on a substrate is used, avoiding complex processes such as photolithography, etching, and cleaning, thus reducing costs. Laser interference-induced positioning growth offers more accurate positioning and higher precision. Simultaneously, it avoids cavity opening operations, preventing contamination of subsequent structure growth and resulting in better structural performance.

[0018] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0020] Figure 1 This is a schematic diagram of the optical path of the laser beam during laser-induced in-situ growth of periodic nanostructures in an embodiment of the present invention.

[0021] Figure 2 This is a microscope image of the periodic nanostructure prepared in Example 1.

[0022] Figure 3 These are schematic diagrams of the three epitaxial structures in the embodiments. Detailed Implementation

[0023] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0024] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0025] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0026] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0027] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0028] Example 1

[0029] The laser-induced in-situ growth method for periodic nanostructures in this embodiment includes the following steps:

[0030] Step 1: Using materials such as GaAs, InP, Al2O3, and GaSb as substrates, keeping the substrate position unchanged, perform the first growth on the substrate using molecular beam epitaxy (MBE) or vapor phase epitaxy (MOCVD) to grow a buffer layer of a certain thickness of materials such as GaAs, InP, GaSb, GaN, SiC, InAs, and GaP to flatten the substrate surface;

[0031] Step 2: Control the substrate temperature to 0-200℃, so that multiple laser beams form interference and irradiate the substrate. At the same time, use MBE or MOCVD to continue growth with materials such as GaAs, InP, GaSb, GaN, SiC, InAs, and GaP for 1-4 hours. After turning off the laser irradiation, a periodic nanostructure is formed.

[0032] This method uses multiple laser beams focused onto a substrate to generate interference. The interference forms periodic bright and dark nano-stripes in the light spot area on the substrate. The bright stripes have high thermal effect and high temperature, while the dark stripes have low thermal effect and low temperature. By controlling the laser parameters and growth conditions, the growth of the induced material at the bright stripes can be controlled, ultimately forming a periodic nanostructure.

[0033] In this embodiment, the substrate includes, but is not limited to, one of GaAs, InP, Al2O3 or GaSb. In the initial growth, the material forming the buffer layer includes, but is not limited to, one of GaAs, InP, GaSb, GaN, SiC, InAs or GaP. In the continued growth, the material forming the periodic nanostructure includes, but is not limited to, one of GaAs, InP, GaSb, GaN, SiC, InAs or GaP.

[0034] In this embodiment or other embodiments, in step two, a laser interference induction device is used for laser interference irradiation. The method by which multiple laser beams are formed in the laser interference induction device is as follows: Figure 1 As shown, a laser beam is rectified by a plano-concave lens 210 and a plano-convex lens 220 and then projected onto a 50:50 beam splitter 300, splitting the beam into two beams of equal intensity. These two beams are then focused onto the substrate 100 by total internal reflection through a reflector 410, resulting in interference.

[0035] In this embodiment or other embodiments, in step two:

[0036] The wavelength of the laser beam is 320-488nm;

[0037] The pulse width of the laser beam is 2-1000 ns;

[0038] The average power of the laser beam is 40-100mW. Too high a power may reduce the epitaxial quality, while too low a power will result in slow growth and ultimately fail to achieve the desired structural effect.

[0039] The angle between the laser beam and the substrate perpendicular to the laser beam is 40-70 degrees.

[0040] In other embodiments, the wavelength, pulse width, average power, and angle of the laser beam with respect to the substrate may be adjusted depending on the growth material and the equipment used.

[0041] In this embodiment, the different polarization states of the laser beam result in different periods of the bright and dark fringes formed by interference, meaning the periods of the in-situ grown nanostructures are different. If the incident laser beam polarization state is TE mode, the period calculation formula is:

[0042]

[0043] If the incident laser beam polarization state is TM mode, then the period calculation formula is:

[0044]

[0045] Where: Λ is the period of the bright and dark stripes in the formula, that is, the period of the nanostructure; λ is the wavelength of the incident laser beam; θ is the angle between the laser and the substrate perpendicular to the direction.

[0046] In this embodiment or other embodiments, after the buffer layer is grown, the Ga source is introduced while the As source remains open until a periodic nanostructure is formed.

[0047] In this embodiment or other embodiments, in step one, the surface oxide of the substrate is first removed to ensure the purity of the substrate before the first growth is performed, thereby ensuring the growth quality and accuracy of the periodic nanostructure.

[0048] In this embodiment or other embodiments, in step one, after the buffer layer is grown for the first time, the lower confinement layer and the multi-quantum well active region are grown, and then step two is performed. This allows the method to grow periodic nanostructures independently, or to grow periodic nanostructures during the growth of epitaxial structures.

[0049] According to this embodiment, laser interference-induced in-situ growth on the substrate avoids complex processes such as photolithography, etching, and cleaning, thus reducing costs. Laser interference-induced positioning growth offers more accurate positioning and higher precision. Simultaneously, it avoids cavity opening operations, preventing contamination of subsequent structure growth and resulting in better structural performance.

[0050] Example 2

[0051] In this specific embodiment, a 2-inch n-type GaAs substrate was deoxideized at 580°C in a microplate separator (MBE), followed by heating to 600°C to grow a 500nm thick n-type GaAs buffer layer. The substrate was then cooled to 200°C, and substrate rotation was stopped. The parameters of the laser interference induction device were adjusted to a laser beam wavelength of 355nm, a pulse width of 2ns, an average power of 52mW, an angle of 64 degrees with the substrate perpendicular to the beam, and a beam polarization state of TE mode. The laser source was turned on, and the laser beam was focused and interfered on the substrate. Simultaneously, the As source in the MBE was kept on, and Ga was slowly passed through. Under these conditions, growth was carried out for 4 hours, thus obtaining a periodic nanostructure. The Ga source, laser induction device, and As source were then turned off, and the substrate was cooled and removed. Figure 2 As shown, the growth region was tested using AFM, and the period of the grown nanostructure was found to be approximately 200 nm.

[0052] Example 3

[0053] In this specific embodiment, a 2-inch n-type GaAs substrate was deoxideized at 580°C in an MBE (Metal-Based Epitaxy) environment. The temperature was then raised to 600°C to grow a 300nm thick n-type GaAs buffer layer. Next, a 1.2µm n-type AlGaAs lower confinement layer was grown sequentially, followed by InGaAs multi-quantum-well active region growth at 500°C. After the above structure growth was complete, the substrate was cooled to 200°C, and substrate rotation was stopped. The parameters of the laser interference induction device were adjusted as follows: laser beam wavelength 355nm, pulse width 2ns, average power 52mW, angle with the substrate perpendicular to 64 degrees, and beam polarization state TE mode. The laser source was turned on, and the laser was focused and interfered on the substrate. Simultaneously, the As source in the MBE was kept on, and Ga was slowly passed through. Growth was carried out under these conditions for 4 hours, thus obtaining a periodic grating structure. Then, the laser induction device was turned off, and the temperature was raised to 600°C to continue growing a 1.2µm p-type AlGaAs upper confinement layer. Finally, a 300nm thick p-type heavily doped GaAs layer was grown to complete the entire epitaxial structure. Thus, the epitaxial structure of the DFB laser prepared by in-situ growth method is formed.

[0054] Example 4

[0055] In this specific embodiment, a 2-inch n-type GaAs substrate was deoxideized at 580°C in a microplate separator (MBE), followed by heating to 600°C to grow a 500nm thick n-type GaAs buffer layer. The substrate was then cooled to 200°C, and substrate rotation was stopped. The parameters of the laser interference induction device were adjusted to a laser beam wavelength of 405nm, a pulse width of 7ns, an average power of 34mW, an angle of 60 degrees with the substrate perpendicular to the beam, and a beam polarization state of TE mode. The laser source was turned on, and the laser beam was focused and interfered on the substrate. Simultaneously, the As source in the MBE was kept on, and Ga was slowly passed through. Under these conditions, growth was carried out for 4 hours, thus obtaining a periodic nanostructure. The Ga source, laser induction device, and As source were turned off, and the substrate was cooled and removed. The grown area was tested using an ablation function (AFM), and the period of the grown nanostructure was found to be approximately 235nm.

[0056] Example 5

[0057] In this specific embodiment, a 2-inch n-type InP substrate was subjected to surface oxide removal in a microplate eclectic apparatus (MBE) at 500-700°C, followed by cooling to 400°C to grow a 300nm thick InP buffer layer. The substrate was then cooled to room temperature, and substrate rotation was stopped. The parameters of the laser interference induction device were adjusted to a laser beam wavelength of 355nm, a pulse width of 5ns, an average power of 40mW, an angle of 64 degrees with the substrate perpendicular to the laser beam, and a beam polarization state of TE mode. The laser source was turned on, and the laser beam was focused and interfered on the substrate. Simultaneously, the P source in the MBE was kept on, and In was slowly introduced. Under these conditions, growth was carried out for 2 hours, thus obtaining a periodic nanostructure. The In source, laser induction device, and P source were turned off, and the substrate was removed. The grown area was tested using an ablation mechanism (AFM), and the period of the grown nanostructure was found to be approximately 198nm.

[0058] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A method for laser-induced in-situ growth of periodic nanostructures, characterized in that, Includes the following steps: Step 1: Perform the first growth on the substrate to form a buffer layer and smooth the substrate surface; after the first growth of the buffer layer is completed, continue to grow the lower confinement layer and the active region; the first growth is carried out by molecular beam epitaxy or vapor phase epitaxy. Step 2: Continue growth on the substrate while irradiating it with multiple laser beams. The multiple laser beams are formed as follows: one laser beam is used to irradiate a beam splitter to form two laser beams, and the two laser beams are respectively irradiated onto the substrate through a reflector to form interference; the substrate temperature is controlled at 0-200℃ for continued growth, and after 1-4 hours of continued growth, a periodic nanostructure is formed; the substrate is one of GaAs, InP, Al2O3 or GaSb; in the first growth, the material forming the buffer layer is one of GaAs, InP, GaSb, GaN, SiC, InAs or GaP; in the continued growth, the material forming the periodic nanostructure is one of GaAs, InP, GaSb, GaN, SiC, InAs or GaP. In step two, the continued growth is carried out using molecular beam epitaxy or vapor phase epitaxy, with a laser beam wavelength of 320-488 nm, a laser beam pulse width of 2-1000 ns, and an average laser beam power of 40-100 mW. The angle between the laser beam and the substrate perpendicular to the substrate is 40-70 degrees.

2. The method for laser-induced in-situ growth of periodic nanostructures according to claim 1, characterized in that, In step one, the surface oxide of the substrate is first removed, and then the first growth is performed.

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