Method for reducing fe tailing on a gan hemt

Abstract

The application is suitable for the technical field of semiconductor substrate material preparation, and provides a method for reducing Fe tailing on a GaN HEMT, which comprises the following steps: placing a substrate into a reaction chamber of a MOCVD device; growing a first GaN layer intentionally doped with Fe on the substrate; growing an AlN layer on the first GaN layer under high-temperature conditions; and growing a second GaN layer unintentionally doped on the AlN layer. In the application, the AlN layer is grown under high-temperature conditions, the small lattice constant of the AlN layer is utilized to increase the compressive stress of the subsequently grown GaN layer unintentionally doped, Fe is prevented from being doped into the GaN layer unintentionally doped through the phenomenon of segregation, and thus the problem of Fe tailing is effectively improved.

Description

Technical Field

[0001] This application belongs to the field of semiconductor substrate material preparation technology, and particularly relates to a method for reducing Fe tailing on GaN HEMT. Background Technology

[0002] During the high-temperature growth of GaN using MOCVD, impurities such as O and Si may be introduced. This will cause GaN to exhibit unintentional doping with a weak n-type structure, resulting in a high background electron concentration, which can even reach 10⁻⁶. 17 cm -3 The magnitude of the doping in GaN substrates means that conductive GaN substrates can form leakage channels between the source and drain. Therefore, this unintentional n-type doping not only continuously degrades the electrical characteristics of microwave devices but also affects optical devices that require controlled doping. Semi-insulating high-resistivity GaN substrates are very effective at suppressing leakage current. Typically, high-resistivity GaN can be obtained by introducing acceptors for compensation. Currently, the main compensation method is to introduce deep-level point defects, such as doping with elements like Fe and Cr.

[0003] However, due to segregation, compensating for background concentration with Fe doping leads to Fe tailing in the sample, where Fe atoms enter the two-dimensional electron gas channel, affecting material performance. Current methods to reduce Fe entry into the two-dimensional electron gas channel primarily involve growing a thicker undoped GaN layer after growing a high-resistivity GaN layer with Fe doping, gradually reducing the Fe doping concentration. The Fe concentration in the channel is altered by adjusting the thickness of the undoped GaN layer. This method requires growing a thick layer of undoped GaN, resulting in a long growth time and hindering cost reduction. Summary of the Invention

[0004] To overcome the problems existing in related technologies, this application provides a method for reducing Fe tailing on GaN HEMTs, in order to solve the phenomenon of Fe tailing in intentionally Fe-doped GaN HEMTs (High Electron Mobility Transistors).

[0005] This application is achieved through the following technical solution:

[0006] In a first aspect, embodiments of this application provide a method for reducing Fe tailing on a GaN HEMT, characterized by comprising: placing a substrate into the reaction chamber of an MOCVD apparatus; growing a first GaN layer intentionally doped with Fe on the substrate; growing an AlN layer on the first GaN layer under high temperature conditions; and growing a second GaN layer unintentionally doped on the AlN layer.

[0007] In conjunction with the first aspect, in some embodiments, the substrate is one of a SiC substrate, a Si substrate, or a sapphire substrate; after placing the substrate into the reaction chamber of the MOCVD equipment, and before growing the first GaN layer, the method further includes raising the temperature of the reaction chamber to a high temperature of 500°C to 1500°C.

[0008] In conjunction with the first aspect, in some embodiments, the temperature of the reaction chamber is increased at a rate of 1.5°C / second.

[0009] In conjunction with the first aspect, in some embodiments, growing a first Fe-doped GaN layer on the substrate includes: introducing a Ga source, ammonia gas, and an Fe source into the reaction chamber; growing a first Fe-doped GaN layer on the substrate under conditions where the temperature of the reaction chamber is 300°C to 1500°C and the pressure is 50 mbar to 1000 mbar; and turning off the Ga source and the ammonia gas, and turning off the Fe source.

[0010] In conjunction with the first aspect, in some embodiments, growing a deliberately Fe-doped first GaN layer on the substrate includes: introducing a Ga source, ammonia gas, and an Fe source into the reaction chamber; growing a deliberately Fe-doped first GaN layer on the substrate under the following conditions: a temperature of 1150°C, a pressure of 200 mbar, a carrier gas flow rate of 20 slm, a Ga source flow rate of 150 sccm, an Fe source flow rate of 150 sccm, an ammonia gas flow rate of 10000 sccm, and a flow time of 10 min; wherein the carrier gas is hydrogen gas; and shutting off the Ga source and the ammonia gas, and shutting off the Fe source.

[0011] In conjunction with the first aspect, in some embodiments, the growth of an AlN layer on the first GaN layer under high-temperature conditions includes: introducing ammonia gas and an Al source into the reaction chamber; and growing an AlN layer on the first GaN layer under the conditions of a temperature of 300°C to 1500°C and a pressure of 50 mbar to 1000 mbar in the reaction chamber.

[0012] In conjunction with the first aspect, in some embodiments, the growth of an AlN layer on the first GaN layer under high-temperature conditions includes: introducing ammonia gas and an Al source into the reaction chamber; and growing an AlN layer on the first GaN layer under the conditions that the temperature of the reaction chamber is 1180°C, the pressure is 50 mbar, the flow rate of the carrier gas is 35 slm, the flow rate of the ammonia gas is 500 sccm, the flow rate of the Al source is 200 sccm, and the introduction time is 3 min.

[0013] In conjunction with the first aspect, in some embodiments, growing an unintentionally doped second GaN layer on the AlN layer includes: introducing a Ga source and ammonia gas into the reaction chamber; and growing an unintentionally doped second GaN layer on the AlN layer under the conditions of a temperature of 300°C to 1500°C and a pressure greater than 0 mbar in the reaction chamber.

[0014] In conjunction with the first aspect, in some embodiments, growing an unintentionally doped second GaN layer on the AlN layer includes: introducing a Ga source and ammonia gas into the reaction chamber; and growing an unintentionally doped second GaN layer on the AlN layer under the conditions that the temperature of the reaction chamber is 1060°C, the pressure is 200 mbar, the flow rate of the carrier gas is 20 slm, the flow rate of the Ga source is 200 sccm, and the flow rate of the ammonia gas is 20000 sccm; wherein the carrier gas is hydrogen gas.

[0015] In conjunction with the first aspect, in some embodiments, the Ga source is trimethylgallium or triethylgallium, the Fe source is ferrocene, and the Al source is trimethylaluminum.

[0016] Secondly, embodiments of this application provide a structure for reducing Fe tailing on a GaN HEMT, comprising: a substrate layer; a first GaN layer intentionally doped with Fe, located above the substrate layer; an AlN layer, located above the first GaN layer; and a second GaN layer unintentionally doped, located above the AlN layer.

[0017] In conjunction with the second aspect, in some embodiments, the substrate layer is made of one of SiC, Si, or sapphire.

[0018] The beneficial effects of the embodiments in this application compared with the prior art are:

[0019] This application provides a method for reducing Fe tailing on GaN HEMTs, including placing a substrate into the reaction chamber of an MOCVD device; growing a first GaN layer intentionally doped with Fe on the substrate; growing an AlN layer on the first GaN layer under high temperature conditions; and growing a second GaN layer unintentionally doped on the AlN layer. In this application, the AlN layer is grown under high temperature conditions. Utilizing the low lattice constant of AlN, the compressive stress of the subsequently grown unintentionally doped GaN layer is increased, preventing Fe from being incorporated into the unintentionally doped GaN layer through segregation, thereby effectively improving the Fe tailing problem. Furthermore, growing an AlN layer on the intentionally Fe-doped GaN layer reduces the growth thickness of the unintentionally doped GaN layer, and the cost of growing an AlN layer is lower than the cost of growing an unintentionally doped GaN layer, thus saving production costs.

[0020] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this specification. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart illustrating a method for reducing Fe tailing on a GaN HEMT according to an embodiment of this application;

[0023] Figure 2 This is a schematic diagram of temperature changes for a method to reduce Fe tailing on a GaN HEMT according to an embodiment of this application;

[0024] Figure 3 This is a schematic diagram of a GaN HEMT structure for reducing Fe tailing provided in an embodiment of this application. Detailed Implementation

[0025] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limiting purposes, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details.

[0026] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0027] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0028] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0029] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0030] GaN is a third-generation semiconductor material. Compared to first-generation silicon (Si) and second-generation gallium arsenide (GaAs), GaN devices have a larger bandgap and higher thermal conductivity, allowing them to operate at temperatures above 200°C, handle higher energy densities, and offer higher reliability. Furthermore, its larger bandgap and higher critical electric field reduce on-resistance, improving overall energy efficiency. Additionally, its fast electron saturation velocity and high carrier mobility enable high-speed operation. Therefore, GaN devices offer advantages such as wider bandwidth, higher gain, higher energy efficiency, and smaller size, making them promising for a wide range of applications.

[0031] During the high-temperature growth of GaN using MOCVD (Metal-Organic Chemical Vapor Deposition), impurities such as O and Si may be introduced. This will cause GaN to exhibit unintentional doping with a weak n-type structure, resulting in a high background electron concentration, which can even reach 10⁻⁶. 17 cm -3 The magnitude of the doping in GaN substrates means that conductive GaN substrates can form leakage channels between the source and drain. Therefore, this unintentional n-type doping not only continuously degrades the electrical characteristics of microwave devices but also affects optical devices that require controlled doping. Semi-insulating high-resistivity GaN substrates are very effective at suppressing leakage current. Typically, high-resistivity GaN can be obtained by introducing acceptors for compensation. Currently, the main compensation method is to introduce deep-level point defects, such as doping with elements like Fe and Cr.

[0032] However, due to segregation, compensating for background concentration with Fe doping leads to Fe tailing in the sample, where Fe atoms enter the two-dimensional electron gas channel, affecting material performance. Current methods to reduce Fe entry into the two-dimensional electron gas channel primarily involve growing a thicker undoped GaN layer after growing a high-resistivity GaN layer with Fe doping, gradually reducing the Fe doping concentration. The Fe concentration in the channel is altered by adjusting the thickness of the undoped GaN layer. This method requires growing a thick layer of undoped GaN and has a long growth time, hindering cost reduction.

[0033] Based on the above problems, the method for reducing Fe tailing on GaN HEMT in this application includes placing a substrate into the reaction chamber of an MOCVD device; growing a first GaN layer intentionally doped with Fe on the substrate; growing an AlN layer on the first GaN layer under high temperature conditions; and growing a second GaN layer unintentionally doped on the AlN layer. Growing the AlN layer under high temperature conditions utilizes the low lattice constant of the AlN layer to increase the compressive stress of the subsequently grown unintentionally doped GaN layer, preventing Fe from being incorporated into the unintentionally doped GaN layer through segregation, thereby effectively improving the Fe tailing problem. Furthermore, growing an AlN layer on the intentionally Fe-doped GaN layer reduces the growth thickness of the unintentionally doped GaN layer, and the cost of growing an AlN layer is lower than the cost of growing an unintentionally doped GaN layer, thus saving production costs.

[0034] Figure 1 This is a schematic flowchart illustrating a method for reducing Fe tailing on a GaN HEMT according to an embodiment of this application, referring to... Figure 1 The method for reducing Fe tailing on GaN HEMT is described in detail below:

[0035] In step 101, the substrate is placed into the reaction chamber of the MOCVD equipment.

[0036] MOCVD is a novel vapor phase epitaxy (VPE) technology developed based on vapor phase epitaxy. An MOCVD apparatus typically consists of a source supply system, a gas transport and flow control system, a reaction chamber and temperature control system, a tail gas treatment and safety alarm system, and an automatic operation and electrical control system. In this embodiment, the substrate is placed in the material growth reaction chamber of the MOCVD apparatus, and vapor phase epitaxy is performed on the substrate.

[0037] In some embodiments, the substrate may be one of a SiC substrate, a Si substrate, or a sapphire substrate.

[0038] In this embodiment of the application, after step 101 and before step 102, the method further includes raising the temperature of the reaction chamber to a high temperature of 500°C to 1500°C. Further, the temperature rise rate of the reaction chamber can be 1.5°C / second.

[0039] In step 102, a first GaN layer intentionally doped with Fe is grown on the substrate.

[0040] In some embodiments, step 102 may specifically include S1021 to S1023:

[0041] In S1021, a Ga source, ammonia gas, and an Fe source are introduced into the reaction chamber.

[0042] The Ga source can be trimethylgallium or triethylgallium, and the Fe source can be ferrocene. The embodiments in this application are only for supplementing the method in this application and are not intended to limit it. Those skilled in the art can choose other Ga or Fe sources according to actual experimental conditions or specific needs.

[0043] In S1022, a first Fe-doped GaN layer is grown on a substrate under the conditions of a reaction chamber temperature of 300°C to 1500°C and a pressure of 50 mbar to 1000 mbar.

[0044] In S1023, the Ga source and ammonia gas are turned off, and the Fe source is turned off.

[0045] In some embodiments, step 102 may include: introducing a Ga source, ammonia gas, and an Fe source into the reaction chamber. Under the conditions of a reaction chamber temperature of 1150°C, a pressure of 200 mbar, a carrier gas flow rate of 20 slm (Standard Liter per Minute), a Ga source flow rate of 150 sccm (Standard Cubic Centimeter per Minute), an Fe source flow rate of 150 sccm, an ammonia gas flow rate of 10000 sccm, and an introduction time of 10 min, a first intentionally Fe-doped GaN layer is grown on the substrate. The Ga source and ammonia gas are then turned off, and the Fe source is also turned off.

[0046] The carrier gas can be hydrogen. In vapor phase epitaxy, the carrier gas is used to carry the vapor of gaseous or liquid precursors into the reaction chamber at a certain flow rate. Precursors are the reactants that participate in the chemical reaction. In MOCVD technology, the metal or organometallic compounds used as precursors are collectively referred to as MO sources.

[0047] In the above embodiments, the growth rate of GaN gradually decreases with increasing temperature, and the utilization efficiency of the MO source also gradually decreases. Lower growth temperatures lead to a decrease in the doping efficiency of the Fe source, making it impossible to achieve the target doping concentration. Therefore, the growth temperature of the first GaN layer needs to be balanced between the utilization efficiency of the Ga source and the doping efficiency of Fe. When the temperature of the reaction chamber is 1150℃, the utilization efficiency of the Ga source is high, while also ensuring the doping efficiency of Fe, thus achieving a good compensation effect for the Fe doping concentration.

[0048] In step 103, an AlN layer is grown on the first GaN layer under high temperature conditions.

[0049] In some embodiments, step 103 may specifically include S1031 and S1032:

[0050] In S1031, ammonia and Al source are introduced into the reaction chamber.

[0051] The Al source can be trimethylaluminum.

[0052] In S1032, an AlN layer is grown on the first GaN layer under the conditions of a reaction chamber temperature of 300°C to 1500°C and a pressure of 50 mbar to 1000 mbar.

[0053] In this embodiment of the application, the Al source can be turned off after the desired AlN layer is obtained.

[0054] In some embodiments, step 103 may include: introducing ammonia gas and an Al source into the reaction chamber. An AlN layer is grown on the first GaN layer under the following conditions: a reaction chamber temperature of 1180°C, a pressure of 50 mbar, a carrier gas flow rate of 35 slm, an ammonia gas flow rate of 500 sccm, an Al source flow rate of 200 sccm, and an introduction time of 3 min.

[0055] Al has a low atomic number and is chemically reactive. On the one hand, Al readily reacts with ammonia (NH3), rapidly producing intermediate reactants, which then generate AlN particles in the gas phase, forming debris that negatively impacts the growth of AlN films. On the other hand, when Al atoms are deposited on the substrate surface, their mean free path is short, making them prone to stacking and forming three-dimensional structures, which is detrimental to the growth of two-dimensional films. Therefore, the growth conditions for AlN layers should involve higher growth temperatures, which not only facilitate the decomposition of the MO source but also increase the mean free path of Al atoms, promoting the growth of two-dimensional films.

[0056] In the above embodiments, the pressure in the reaction chamber is 50 mbar. This is because, during AlN layer growth, it is necessary to minimize the pressure to reduce the gas concentration within the reaction chamber, thereby minimizing the generation of gaseous intermediates. Simultaneously, the ammonia flow rate during AlN layer growth is 500 sccm, significantly lower than the ammonia flow rate during the growth of the first GaN layer. This lower ammonia flow rate reduces the partial pressure of ammonia within the reaction chamber, further reducing the generation of gaseous intermediates.

[0057] In the above embodiment, under high temperature conditions, after the growth of the first Fe-doped GaN layer, an AlN layer is grown. By introducing the AlN layer, the stress of the subsequent GaN layer is changed, making it difficult for Fe to be incorporated into GaN, which can effectively improve the Fe tailing phenomenon.

[0058] In step 104, an unintentionally doped second GaN layer is grown on the AlN layer.

[0059] In some embodiments, step 104 may specifically include S1041 and S1042:

[0060] In S1041, a Ga source and ammonia gas are introduced into the reaction chamber.

[0061] In S1042, an unintentionally doped second GaN layer is grown on the AlN layer under the conditions of a reaction chamber temperature of 300°C to 1500°C and a pressure greater than 0 mbar.

[0062] In some embodiments, step 104 may include: introducing a Ga source and ammonia gas into the reaction chamber. Under conditions of a reaction chamber temperature of 1060°C, a pressure of 200 mbar, a carrier gas flow rate of 20 slm, a Ga source flow rate of 200 sccm, and an ammonia gas flow rate of 20000 sccm, an unintentionally doped second GaN layer is grown on the AlN layer. The carrier gas may be hydrogen gas.

[0063] After growing an intentionally Fe-doped first GaN layer and turning off the Fe source, the unintentionally doped second GaN layer is weakly N-type. Due to the memory effect, the Fe tailing will gradually decrease, eventually failing to compensate for the intrinsic electron concentration of the GaN layer, leading to device failure. Therefore, when growing unintentionally doped GaN, a slightly lower growth temperature should be selected to facilitate the incorporation of C atoms from the MO source, thereby compensating for the intrinsic electron concentration of the GaN layer and improving device performance.

[0064] Figure 2 This is a schematic diagram of the temperature change of a method for reducing Fe tailing on GaN HEMT according to an embodiment of this application. See [link / reference]. Figure 2Stage 21 involves heating the reaction chamber at a rate of 1.5°C / second after placing the substrate inside. Heating is stopped when the temperature reaches 1150°C, and the process proceeds to Stage 22. The pressure in the reaction chamber is adjusted to 200 mbar. Trimethylgallium (TMG), ammonia, and ferrocene are introduced into the reaction chamber using hydrogen gas. The flow rates are set as follows: hydrogen flow rate 20 slm, TMG flow rate 150 sccm, ferrocene flow rate 150 sccm, and NH3 flow rate 10000 sccm for 10 min, thereby growing an intentionally Fe-doped first GaN layer on the substrate. At node 23, the TMG and ammonia gases are shut off, and the ferrocene gas is also turned off. Adjust the temperature and pressure of the reaction chamber. When the temperature reaches 1180℃ and the pressure reaches 50 mbar, proceed to stage 24. In this stage, ammonia and trimethylaluminum are introduced into the reaction chamber using hydrogen gas at a flow rate of 35 slm, ammonia at 500 sccm, trimethylaluminum at 200 sccm, and a duration of 3 minutes. An AlN layer is then grown on the first GaN layer. The trimethylaluminum is then turned off. Next, adjust the temperature and pressure of the reaction chamber. When the temperature reaches 1060℃ and the pressure reaches 200 mbar, proceed to stage 25. In this stage, trimethylgallium and ammonia are introduced into the reaction chamber using hydrogen gas at a flow rate of 20 slm, trimethylgallium at 200 sccm, and ammonia at 20000 sccm. An unintentionally doped second GaN layer is then grown on the AlN layer.

[0065] The aforementioned method for reducing Fe tailing on GaN HEMTs involves growing an AlN layer on a first GaN layer under high-temperature conditions, followed by an unintentionally doped second GaN layer. Utilizing the lower lattice constant of the inserted AlN layer, the compressive stress on the second GaN layer is increased, thereby reducing its lattice constant. Considering the atomic weight of Fe, with a lower lattice constant in the second GaN layer, it is difficult for Fe to incorporate into it. Therefore, this method can prevent Fe from being incorporated into the unintentionally doped GaN through segregation, effectively improving the Fe tailing problem. On the other hand, growing an AlN layer on an intentionally Fe-doped GaN layer reduces the thickness of the unintentionally doped GaN layer compared to methods that grow thicker undoped GaN layers. Since the cost of growing an AlN layer is lower than that of growing an unintentionally doped GaN layer, production costs can be saved.

[0066] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0067] Corresponding to the method for reducing Fe tailing on GaN HEMT described in the above embodiments, Figure 3 The diagram shows a schematic of a GaN HEMT structure for reducing Fe tailing according to an embodiment of this application, including: a substrate layer 310; a first GaN layer 320 intentionally doped with Fe, located above the substrate layer 310; an AlN layer 330, located above the first GaN layer 320; and a second GaN layer 340 unintentionally doped, located above the AlN layer 330.

[0068] In some embodiments, the substrate layer 310 may be made of SiC, Si, or sapphire.

[0069] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for reducing Fe tailing on GaN HEMT, characterized in that, include: Place the substrate into the reaction chamber of the MOCVD equipment; A first Fe-doped GaN layer is grown on the substrate; An AlN layer is grown on the first GaN layer under high temperature conditions; An unintentionally doped second GaN layer is grown on an AlN layer; When the intentionally Fe-doped first GaN layer is grown on the substrate, the temperature of the reaction chamber is 1150°C and the pressure is 200 mbar. When growing an AlN layer on the first GaN layer, the temperature of the reaction chamber is 1180°C and the pressure is 50 mbar. When an unintentionally doped second GaN layer is grown on the AlN layer, the temperature of the reaction chamber is 1060°C; The AlN layer is used to increase the compressive stress of the second GaN layer, so as to reduce the lattice constant of the second GaN layer and prevent Fe from being incorporated into the second GaN layer through segregation. The process of growing a first Fe-doped GaN layer on the substrate includes: introducing a Ga source, ammonia gas, and an Fe source into the reaction chamber; wherein the flow rate of the ammonia gas is 10000 sccm. Growing an AlN layer on the first GaN layer includes: introducing ammonia gas and an Al source into the reaction chamber; wherein the flow rate of the ammonia gas is 500 sccm.

2. The method for reducing Fe tailing on GaN HEMT as described in claim 1, characterized in that, The growth of the intentionally Fe-doped first GaN layer on the substrate includes: Under the conditions that the flow rate of the carrier gas in the reaction chamber is 20 slm, the flow rate of the Ga source is 150 sccm, the flow rate of the Fe source is 150 sccm, and the infusion time is 10 min, a first Fe-doped GaN layer is grown on the substrate; wherein the carrier gas is hydrogen. The Ga source and the ammonia gas are shut off, and the Fe source is shut off.

3. The method for reducing Fe tailing on GaN HEMT as described in claim 1, characterized in that, The process of growing an AlN layer on a first GaN layer under high temperature conditions includes: An AlN layer is grown on the first GaN layer under the following conditions: the flow rate of the carrier gas in the reaction chamber is 35 slm, the flow rate of the Al source is 200 sccm, and the infusion time is 3 min; wherein the carrier gas is hydrogen and the Al source is trimethylaluminum.

4. The method for reducing Fe tailing on GaN HEMT as described in claim 1, characterized in that, The growth of an unintentionally doped second GaN layer on the AlN layer includes: A Ga source and ammonia gas are introduced into the reaction chamber; Under the condition that the pressure in the reaction chamber is greater than 0 mbar, an unintentionally doped second GaN layer is grown on the AlN layer.

5. The method for reducing Fe tailing on GaN HEMT as described in claim 1, characterized in that, The growth of an unintentionally doped second GaN layer on the AlN layer includes: A Ga source and ammonia gas are introduced into the reaction chamber; An unintentionally doped second GaN layer is grown on an AlN layer under the following conditions: a pressure of 200 mbar in the reaction chamber, a carrier gas flow rate of 20 slm, a Ga source flow rate of 200 sccm, and an ammonia flow rate of 20000 sccm; wherein the carrier gas is hydrogen.

6. The method for reducing Fe tailing on GaN HEMT as described in claim 2, characterized in that, The Ga source is trimethylgallium or triethylgallium, and the Fe source is ferrocene.

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