Novel epitaxial structure based on irradiation two-dimensional h-BN and preparation method

Abstract

The invention relates to the technical field of semiconductors, in particular to a novel epitaxial structure based on irradiation two-dimensional h-BN and a preparation method thereof.The structure comprises a free substrate, a buffer layer and a GaN epitaxial layer which are sequentially arranged from bottom to top, and the buffer layer comprises an irradiation two-dimensional h-BN layer, a low-temperature AlN layer and a high-temperature AlN layer; the irradiation two-dimensional h-BN layer is made of two-dimensional h-BN / Cu foil through nitrogen ion irradiation and gradient annealing processes. According to the method, h-BN is modified through nitrogen ion irradiation, the influence of the substrate is shielded, carrier scattering can be avoided, and local lattice reconstruction is induced to form epitaxial nucleation points while irradiation defects are stabilized through a gradient annealing process.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, specifically to a novel epitaxial structure based on irradiated two-dimensional h-BN and its preparation method. Background Technology

[0002] Third-generation semiconductors, represented by gallium nitride and silicon carbide, have attracted much attention due to their advantages such as band gaps higher than 3 eV, high critical breakdown field strength, and high electron saturation drift velocity. Among them, GaN and its alloy materials are widely used in power electronic devices and radio frequency devices because of their ideal band structure and strain engineering properties.

[0003] Based on experience in studying the interface characteristics of gallium arsenide-based heterojunctions, GaN high electron mobility transistors (HEMTs) with AlGaN / GaN heterojunctions as their core have emerged and are gradually being commercialized. Due to their unique properties and excellent radiation resistance, GaN-based HEMTs have enormous application potential in key fields such as satellites, space exploration, and nuclear reactors.

[0004] However, GaN heteroepitaxy is still limited by substrate selection, which severely restricts the further improvement of GaN HEMT performance. Summary of the Invention

[0005] To address the problems in the prior art, this invention provides a novel epitaxial structure based on irradiated two-dimensional h-BN and its preparation method.

[0006] This invention is achieved through the following technical solution: A novel epitaxial structure based on irradiated two-dimensional h-BN includes a free substrate, a buffer layer, and a GaN epitaxial layer arranged sequentially from bottom to top. The buffer layer includes an irradiated two-dimensional h-BN layer, a low-temperature AlN layer, and a high-temperature AlN layer. The irradiated two-dimensional h-BN layer is fabricated from a two-dimensional h-BN / Cu foil by nitrogen ion irradiation and gradient annealing.

[0007] A method for preparing a novel epitaxial structure based on irradiated two-dimensional h-BN as described in claim 1, comprising: Step 1: Peel off the two-dimensional h-BN / Cu foil; Step 2: Transfer the two-dimensional h-BN / Cu foil onto a free substrate; Step 3: Irradiate two-dimensional h-BN / Cu foil with nitrogen ions in a vacuum environment to obtain modified two-dimensional h-BN; Step 4: The modified two-dimensional material h-BN is treated with gradient annealing under a nitrogen atmosphere to obtain a stable two-dimensional irradiated h-BN layer. Step 5: Epitaxially grow high- and low-temperature AlN layers on a stable two-dimensional irradiated h-BN layer, and then epitaxially grow a GaN barrier layer to obtain a novel epitaxial structure based on irradiated two-dimensional h-BN.

[0008] Preferably, in step 1, plasma-assisted stripping of h-BN from the copper foil is used.

[0009] Preferably, in step 2, a transfer imprinting technique is used to transfer a two-dimensional h-BN / Cu foil onto a free substrate at 55±5℃ with a gravity of 300±10g.

[0010] Preferably, in step 3, irradiation is performed using a 5-30 keV nitrogen ion beam, and the dose of the nitrogen ion beam is 1. 10 14 ~1 10 16 ions / cm -2 The irradiation time is 10~30s.

[0011] Preferably, in step 5, the gradient annealing process includes a first stage and a second stage, the total annealing time is 1~2 hours, and nitrogen gas is introduced at a flow rate of 1~3 L / min; In the first stage, the temperature is 300~400℃ and the time is 1~2 hours; In the second stage, the temperature is increased from 300~400℃ to 800~1000℃ at a rate of 3~8℃ / min.

[0012] Preferably, in step 6, the high and low temperature AlN layers include a low temperature aluminum nitride layer and a high temperature aluminum nitride layer.

[0013] Preferably, the low-temperature aluminum nitride layer is epitaxially grown at 800°C and has a thickness of 100 nm.

[0014] Preferably, the high-temperature aluminum nitride layer is epitaxially grown at 1000℃ and has a thickness of 150nm.

[0015] A novel epitaxial GaN device comprising the aforementioned two-dimensional h-BN irradiated structure.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a novel epitaxial structure based on irradiated two-dimensional h-BN. Utilizing the characteristics of two-dimensional h-BN, the unique layer structure of two-dimensional h-BN (two-dimensional hexagonal boron nitride) can induce epitaxial layer defect co-exposition. Based on this, surface atomic-level coordination defects can be constructed through controlled irradiation. With the design of a buffer layer structure, precise substrate selection freedom can be achieved, ensuring the improvement of device performance. Therefore, this invention is of great significance to the development of existing power devices. In this invention, a novel epitaxial structure based on irradiated two-dimensional H-BN is prepared by irradiating the two-dimensional material h-BN with nitrogen ion beams at different doses in a vacuum environment for short periods of time, controlling the time and quantity, to modify the two-dimensional material h-BN. Then, annealing is carried out in a nitrogen atmosphere to eliminate the unstable defects of the two-dimensional material h-BN and ensure the stability of the two-dimensional material h-BN.

[0017] Furthermore, the first annealing is used to stabilize irradiation defects, while the second annealing, which gradually increases to a high temperature, is used to induce local lattice reconstruction to form epitaxial nucleation sites. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a novel epitaxial structure based on irradiated two-dimensional h-BN according to the present invention; Figure 2 This is a flowchart illustrating the fabrication process of a novel epitaxial structure based on irradiated two-dimensional h-BN according to the present invention.

[0019] In the figure: 1. Free substrate; 2. Irradiated two-dimensional h-BN layer; 3. Low-temperature AlN layer; 4. High-temperature AlN layer; 5. GaN epitaxial layer. Detailed Implementation

[0020] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0021] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0022] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0023] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0024] This invention discloses a novel epitaxial structure based on irradiated two-dimensional h-BN, with reference to... Figure 1The structure comprises, from bottom to top, a free substrate 1, a buffer layer, and a GaN epitaxial layer 5. The buffer layer includes an irradiated two-dimensional h-BN layer 2, a low-temperature AlN layer 3, and a high-temperature AlN layer 4. The irradiated two-dimensional h-BN layer 2 is fabricated from a two-dimensional h-BN / Cu foil using nitrogen ion irradiation and gradient annealing. This structure provides flexibility in choosing a free substrate, such as peelable GaN devices, vertical LED devices (by transferring GaN thin films onto highly thermally and electrically conductive metal or Si substrates, vertical LED devices can be fabricated), flexible devices (such as transferring GaN-based ultraviolet photodetectors onto flexible substrates for use in wearable devices and other fields), and high-performance electronic devices (GaN devices can be integrated with high-performance substrates through peeling and transfer techniques to improve device performance).

[0025] This invention also discloses a method for preparing a novel epitaxial structure of two-dimensional h-BN irradiated by radiation, referring to... Figure 2 ,include: Step 1: Plasma-assisted stripping of two-dimensional h-BN / Cu foil; Step 2: Transfer the two-dimensional h-BN / Cu foil onto the free substrate 1.

[0026] Specifically, a two-dimensional h-BN / Cu foil was transferred onto a free substrate 1 at 55±5℃ with a gravity of 300±10g.

[0027] Step 3: Irradiate a two-dimensional h-BN / Cu foil in a vacuum environment to obtain modified two-dimensional h-BN.

[0028] Specifically, irradiation is performed using a 5-30 keV nitrogen ion beam, with a nitrogen ion beam dose of 1×10¹⁴-1×10¹⁶ ions / cm⁻² and an irradiation time of 10-30 s.

[0029] Step 4: The modified two-dimensional material h-BN is treated with a gradient annealing process under a nitrogen atmosphere to obtain a stable two-dimensional irradiated h-BN layer.

[0030] Specifically, the gradient annealing process includes a first stage and a second stage, with a total annealing time of 1-2 hours and nitrogen gas introduced at a rate of 1-3 L / min. In the first stage, the temperature is 300~400℃ and the time is 1~2 hours; In the second stage, the temperature is increased from 300~400℃ to 800~1000℃ at a rate of 3~8℃ / min.

[0031] Step 5: Epitaxially grow high- and low-temperature AlN layers 3 on a stable two-dimensional irradiated h-BN layer, and then epitaxially grow a GaN barrier layer to obtain a novel epitaxial structure based on irradiated two-dimensional h-BN.

[0032] Among them, the high and low temperature AlN layer 3 includes a low temperature aluminum nitride layer and a high temperature aluminum nitride layer. The low temperature aluminum nitride layer is epitaxially grown at 800℃ and has a thickness of 100nm, while the high temperature aluminum nitride layer is epitaxially grown at 1000℃ and has a thickness of 150nm.

[0033] This invention modifies h-BN by nitrogen ion irradiation, shielding it from substrate influences and preventing carrier scattering. Gradient annealing stabilizes irradiation defects while inducing local lattice reconstruction to form epitaxial nucleation sites. Different process steps reduce dislocation density in the epitaxial layer, achieving defect coalescence and improving device performance. Due to the unique properties of two-dimensional materials, this method is unaffected by the substrate lattice. The design method differs theoretically from traditional substrate-constrained approaches. Different designers can adjust the method according to different products, and results meeting product requirements can be obtained by following this approach, making it widely applicable.

[0034] The present invention also discloses a novel epitaxial GaN device comprising the aforementioned two-dimensional h-BN irradiated epitaxial structure.

[0035] Example Step 1: Plasma-assisted stripping of two-dimensional h-BN / Cu foil. Specifically, plasma is used to strip the h-BN from the copper foil. The copper foil is cut into the appropriate shape according to the size of the substrate. First, the substrate surface is cleaned with acetone to remove organic contaminants and particles, ensuring the stability of subsequent processes. For the interfaces that need to be stripped, the surface energy is changed through chemical modification or plasma activation to promote subsequent stripping.

[0036] The plasma source is divided into reactive plasma (used for chemical etching or surface modification) and inert plasma (weakens the interfacial bonding force through physical bombardment). In order not to damage the h-BN film on the copper foil, a power of 200W and a gas pressure of 2Pa are used here, and the processing time is 1min, so as to balance the stripping efficiency and substrate damage.

[0037] Based on this, the interface cracks are expanded by thermal stress (heating to 100~300℃), and then h-BN is transferred to the target substrate using a precision fixture.

[0038] Step 2: Transfer the two-dimensional h-BN / Cu foil onto the free substrate.

[0039] Specifically, a transfer imprinting technique is used to transfer a two-dimensional h-BN / Cu foil onto a free substrate at 55°C with a gravity of 300.

[0040] Step 3: Irradiate a two-dimensional h-BN / Cu foil in a vacuum environment to obtain modified two-dimensional h-BN.

[0041] Specifically, irradiation with a 20keV nitrogen ion beam was used, and the dose of the nitrogen ion beam was 1. 10 15 ions / cm -2 The irradiation time was 20 seconds.

[0042] Step 4: The modified two-dimensional material h-BN is treated with a gradient annealing process under a nitrogen atmosphere to obtain a stable two-dimensional irradiated h-BN layer.

[0043] Specifically, the gradient annealing process includes a first stage and a second stage, with a total annealing time of 2 hours and a nitrogen flow rate of 2 L / min. In the first stage, the temperature is 350℃ and the time is 30 hours; In the second stage, the temperature was increased from 350℃ to 800℃ at a rate of 5℃ / min.

[0044] Step 5: Epitaxially grow high- and low-temperature AlN layers on a stable two-dimensional irradiated h-BN layer, and then epitaxially grow a GaN barrier layer to obtain a novel epitaxial structure based on irradiated two-dimensional h-BN.

[0045] The high and low temperature AlN layers include a low temperature aluminum nitride layer and a high temperature aluminum nitride layer. The low temperature aluminum nitride layer is epitaxially grown at 800℃ and has a thickness of 100nm, while the high temperature aluminum nitride layer is epitaxially grown at 1000℃ and has a thickness of 150nm.

[0046] Comparative Example Step 1: Peel off the two-dimensional h-BN / Cu foil; Step 2: Transfer the two-dimensional h-BN / Cu foil onto a free substrate; Step 3: Epitaxially grow high- and low-temperature AlN layers on a stable two-dimensional irradiated h-BN layer, and then epitaxially grow a GaN barrier layer to obtain a novel epitaxial structure based on irradiated two-dimensional h-BN.

[0047] Based on the experimental results presented by the two sets of techniques—unirradiated (comparative example) and irradiated (example) GaN—GaN epitaxial growth on substrates with disordered crystal arrangement, such as diamond, shows that the GaN film irradiated with h-BN as a buffer layer can exhibit low dislocation merging film at the level of about 100 micrometers. However, on the diamond substrate without h-BN irradiation, a flat GaN film cannot be formed, resulting in disordered arrangement of Ga and N atoms. This buffer layer technique can be used on any amorphous substrate, such as glass, greatly expanding the application fields of GaN devices.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the technical solution of the present invention in any way. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can be modified and replaced in several simple ways, and these modifications and replacements are all within the scope of protection covered by the claims.

Claims

1. A novel epitaxial structure based on irradiated two-dimensional h-BN, characterized in that, The application relates to a GaN epitaxial wafer, which comprises, from bottom to top, a free substrate, a buffer layer and a GaN epitaxial layer, wherein the buffer layer comprises an irradiated two-dimensional h-BN layer, a low-temperature AlN layer and a high-temperature AlN layer, and the irradiated two-dimensional h-BN layer is made of a two-dimensional h-BN / Cu foil through nitrogen ion irradiation and gradient annealing processes.

2. A method of producing a novel epitaxial structure based on irradiated two-dimensional h-BN according to claim 1, characterized in that, The application relates to a GaN epitaxial wafer, which comprises, from bottom to top, a free substrate, a buffer layer and a GaN epitaxial layer, wherein the buffer layer comprises an irradiated two-dimensional h-BN layer, a low-temperature AlN layer and a high-temperature AlN layer, and the irradiated two-dimensional h-BN layer is made of a two-dimensional h-BN / Cu foil through nitrogen ion irradiation and gradient annealing processes. The application relates to a GaN epitaxial wafer, which comprises, from bottom to top, a free substrate, a buffer layer and a GaN epitaxial layer, wherein the buffer layer comprises an irradiated two-dimensional h-BN layer, a low-temperature AlN layer and a high-temperature AlN layer, and the irradiated two-dimensional h-BN layer is made of a two-dimensional h-BN / Cu foil through nitrogen ion irradiation and gradient annealing processes. The application relates to a GaN epitaxial wafer, which comprises, from bottom to top, a free substrate, a buffer layer and a GaN epitaxial layer, wherein the buffer layer comprises an irradiated two-dimensional h-BN layer, a low-temperature AlN layer and a high-temperature AlN layer, and the irradiated two-dimensional h-BN layer is made of a two-dimensional h-BN / Cu foil through nitrogen ion irradiation and gradient annealing processes. The application relates to a GaN epitaxial wafer, which comprises, from bottom to top, a free substrate, a buffer layer and a GaN epitaxial layer, wherein the buffer layer comprises an irradiated two-dimensional h-BN layer, a low-temperature AlN layer and a high-temperature AlN layer, and the irradiated two-dimensional h-BN layer is made of a two-dimensional h-BN / Cu foil through nitrogen ion irradiation and gradient annealing processes. In step 1, the h-BN on the copper foil is peeled off by adopting plasma-assisted peeling. In step 2, the two-dimensional h-BN / Cu foil is transferred to the free substrate by adopting a transfer stamping technology, and the two-dimensional h-BN / Cu foil is transferred to the free substrate under the condition that the temperature is 55+ / -5 DEG C and the gravity is 300+ / -10 g.

3. The novel epitaxial structure based on irradiated two-dimensional h-BN according to claim 2, characterized in that, In step 5, the gradient annealing process comprises a first stage and a second stage, nitrogen gas with a flow rate of 1-3 L / min is introduced, and the whole annealing time is 1-2 h.

4. The novel epitaxial structure based on irradiated two-dimensional h-BN according to claim 3, characterized in that, In the first stage, the temperature is 300-400 DEG C, and the time is 1-2 h.

5. The novel epitaxial structure based on irradiated two-dimensional h-BN according to claim 4, characterized in that, In step 3, the 5-30 keV nitrogen ion beam is irradiated at a dose of 1 10 14 ~1 10 16 ions / cm -2 for 10-30 s.

6. The novel epitaxial structure based on irradiated two-dimensional h-BN according to claim 2, wherein In the second stage, the temperature is increased from 300-400 DEG C to 800-1000 DEG C at a rate of 3-8 DEG C / min. In step 6, the high and low temperature AlN layers comprise a low-temperature aluminum nitride layer and a high-temperature aluminum nitride layer. The low-temperature aluminum nitride layer is epitaxially grown at 800 DEG C and has a thickness of 100 nm.

7. The novel epitaxial structure based on irradiated two-dimensional h-BN according to claim 1, characterized in that The high-temperature aluminum nitride layer is epitaxially grown at 1000 DEG C and has a thickness of 150 nm.

8. The novel epitaxial structure based on irradiated two-dimensional h-BN according to claim 7, characterized in that, 10. A GaN device containing the novel epitaxial structure based on the irradiated two-dimensional h-BN according to claim 1.

9. The novel epitaxial structure based on irradiated two-dimensional h-BN according to claim 7, wherein ​ ​

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