Nitride semiconductor device, radio frequency amplifier, and communication apparatus

Abstract

The invention discloses a nitride semiconductor device, which comprises a first nitride layer, a second nitride layer and a third nitride layer, a second nitride layer disposed on the first nitride layer; the second nitride layer is composed of a first element, a second element and a third element, the first element is an aluminum element, the second element is a nitrogen element, the third element is a gallium element, and the concentration of the first element is gradually increased in the thickness direction; the third nitride layer is arranged on the second nitride layer, and the third nitride layer is a ternary nitrogen compound or a quaternary nitrogen compound; the maximum value of the first element concentration of the second nitride layer is smaller than or equal to the first element concentration value of the third nitride layer; in the thickness direction, the thickness of the first nitride layer is d1, the thickness of the second nitride layer is d2, and d2 is smaller than d1; compared with the prior art, the nitride semiconductor device has the advantages that the current density of the device can be improved, the leakage current is reduced, and the reliability of the device is improved.

Description

Technical Field

[0001] This invention relates to the field of nitride semiconductors, and particularly to semiconductor devices used in the field of radio frequency. Background Technology

[0002] GaN-based high electron mobility transistors (GaN HEMTs) utilize the strong piezoelectric polarization effect of AlGaN / GaN heterojunctions to form a high-mobility, high-density two-dimensional electron gas (2DEG) at the interface, thereby enabling high-frequency signal processing and transmission under high power conditions.

[0003] JP2004200711A discloses a technique for improving electrical characteristics by setting an AlN enhancement layer between the electron transport layer and the electron supply layer. The thickness of the AlN enhancement layer is more than one molecular layer to four molecular layers; in one embodiment, the thickness of the AlN enhancement layer is set to two molecular layers to five angstroms. The AlN layer has a large band gap of 6.2 eV, which can reduce the probability of current injection from the channel layer to the barrier layer, thus functioning as a heterojunction. Furthermore, in practical applications of GaN RF devices, the AlN insertion layer cannot be too thick, generally set at around 0.2–2 nm; otherwise, it is prone to causing excessive gate leakage current and drain leakage current, leading to device reliability failure. Conversely, an excessively thin AlN insertion layer will not achieve the effect of increasing current density.

[0004] Therefore, how to improve carrier concentration, reduce scattering, and thus increase current density in GaN HEMT while ensuring reliability is a current technical challenge. Summary of the Invention

[0005] To address the above problems, this invention provides a nitride semiconductor device that can increase the current density of the device while reducing leakage current, thereby improving the reliability of the device.

[0006] To achieve the above objectives, in one specific embodiment of the present invention, a method for fabricating a high electron mobility transistor is provided, comprising the following:

[0007] A nitride semiconductor device includes a first nitride layer, which is a binary nitrogen compound; a second nitride layer disposed on the first nitride layer; the first nitride layer has opposing first and second surfaces, the second surface being the interface between the first and second nitride layers, and the direction from the first surface to the second surface is defined as the thickness direction; the second nitride layer is composed of a first element, a second element, and a third element, wherein the first element is aluminum, the second element is nitrogen, and the third element is gallium, and the concentration of the first element increases along the thickness direction; a third nitride layer disposed on the second nitride layer, which is a ternary nitrogen compound or a quaternary nitrogen compound; the band gap of the third nitride layer is larger than that of the second nitride layer, generating a two-dimensional electron gas within the first nitride layer; the maximum concentration of the first element in the second nitride layer is less than or equal to the concentration of the first element in the third nitride layer; along the thickness direction, the thickness of the first nitride layer is d1, the thickness of the second nitride layer is d2, and the thickness of the third nitride layer is d3; wherein d2 < d1. In a further preferred embodiment,

[0008] Furthermore, the nitride semiconductor device also includes a substrate, and a nucleation layer is provided between the substrate and the first nitride layer.

[0009] Furthermore, the nitride semiconductor device also includes a cap layer, which is an unintentionally doped GaN layer.

[0010] Furthermore, along the thickness direction, the thickness of the cap layer is d4, and the sum of the thicknesses of the second nitride layer, the third nitride layer, and the cap layer is d2 + d3 + d4, where,

[0011] In one specific embodiment of the present invention, the first nitride layer is an unintentionally doped GaN layer; wherein, Furthermore, the sum of the thicknesses of the first nitride layer and the second nitride layer is d1 + d2, where, The ratio of the thickness of the first nitride layer to the thickness of the second nitride layer is d1 / d2, where 17 ≤ d1 / d2 ≤ 1000. In a further preferred embodiment, 35 ≤ d1 / d2 ≤ 350.

[0012] Furthermore, in the nitride semiconductor device of the present invention, the third nitride layer is AlyGa1-yN, In1-zAlzN, or InkAljGa1-j-kN; wherein, 15% ≤ y ≤ 35%; 70 ≤ z ≤ 100%; 0 < k ≤ 20%; and 10% ≤ j < 80%.

[0013] In another specific embodiment of the present invention, the first nitride layer includes a first GaN layer and a second GaN layer disposed on the first GaN layer; the second GaN layer is an unintentionally doped GaN layer with a thickness ranging from [missing information]. The first GaN layer is a C- or Fe-doped GaN layer, wherein Furthermore, the sum of the thicknesses of the first nitride layer and the second nitride layer is d1 + d2, where, Wherein, 50≤d1 / d2≤5000. In a further preferred embodiment, where 100≤d1 / d2≤3000.

[0014] Furthermore, in the nitride semiconductor device of the present invention, the ratio of the thickness of the third nitride layer to the thickness of the second nitride layer is d3 / d2; wherein 2≤d3 / d2≤70. In a further preferred embodiment, 5≤d3 / d2≤20.

[0015] Accordingly, the present invention also provides a radio frequency amplifier, including the above-described nitride semiconductor device.

[0016] Accordingly, the present invention also provides a communication device including the radio frequency amplifier described above.

[0017] The nitride semiconductor device of this invention utilizes a second nitride layer disposed between the channel layer and the barrier layer. This second nitride layer is composed of a first element, a second element, and a third element, wherein the first element is aluminum, the second element is nitrogen, and the third element is gallium, with the concentration of the first element increasing along the thickness direction. This can improve the device's current intensity by 15%. Meanwhile, the prior art, by adding an AlN insertion layer, exhibits high leakage current during high-temperature reverse bias tests. The structure of this invention reduces the leakage current during high-temperature reverse bias tests to 1 / 10 of that of the prior art, thus improving device reliability while increasing current density. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the nitride semiconductor device in Example 1;

[0019] Figure 2 This is a schematic diagram of a nitride semiconductor device including a nucleation layer according to Example 1;

[0020] Figure 3 This is a schematic diagram of a nitride semiconductor device including a nucleation layer and a capping layer according to Example 1;

[0021] Figure 4 This is a comparison graph of the Ids-Vds curves of AlGaN / GaN HEMT at Vgs = 2V between the present invention and a comparative example;

[0022] Figure 5 This is a comparison diagram of leakage current in the high temperature reverse bias test (HTRB) of the present invention and the comparative example.

[0023] Figure 6 This is a schematic diagram of the nitride semiconductor device in Example 2;

[0024] Figure 7 This is a schematic diagram of a nitride semiconductor device including a nucleation layer according to Example 2;

[0025] Figure 8 This is a schematic diagram of a nitride semiconductor device including a nucleation layer and a cap layer according to Example 2. Detailed Implementation

[0026] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0027] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. The accompanying drawings in this specification are only illustrative; it should be understood that the dimensions of the various parts shown in the drawings are not drawn to actual scale.

[0028] Example 1

[0029] This invention provides a nitride semiconductor device, as shown in the attached figure. Figure 1The device includes a source (S), a drain (D), and a gate (G). The source (S) and drain (D) are disposed opposite each other on the epitaxial layer of the nitride semiconductor device. The gate (G) is disposed on the epitaxial layer between the source (S) and drain (D). The epitaxial layer includes a first nitride layer 1 disposed on a substrate 10, the first nitride layer 1 being a binary nitrogen compound; and a second nitride layer 2 disposed on the first nitride layer 1. The first nitride layer has opposing first surfaces 1a and 1b, the second surface 1b being the interface between the first nitride layer and the second nitride layer. The direction from surface 1a to surface 1b is defined as the thickness direction x; the second nitride layer is composed of a first element, a second element, and a third element, wherein the first element is aluminum, the second element is nitrogen, and the third element is gallium, and the concentration of the first element increases along the thickness direction x; a third nitride layer is disposed on the second nitride layer 2, wherein the third nitride layer 3 is a ternary nitrogen compound or a quaternary nitrogen compound; the first nitride layer 1, the second nitride layer 2, and the third nitride layer 3 constitute the epitaxial layer of the nitride semiconductor device.

[0030] The band gap of the third nitride layer 3 is larger than that of the second nitride layer 2, generating a two-dimensional electron gas within the first nitride layer 1; the maximum value of the first element concentration in the second nitride layer 2 is less than or equal to the first element concentration value in the third nitride layer 3; along the thickness direction x, the thickness of the first nitride layer is d1, the thickness of the second nitride layer is d2, and the thickness of the third nitride layer is d3; wherein, d2 < d1.

[0031] In this embodiment of the invention, the first nitride layer 1 is an unintentionally doped GaN layer; wherein,

[0032] In a more preferred embodiment, preferably When d2 value is less than The second nitride layer forms a high potential barrier on the AlGaN side of the 2DEG interface. This barrier provides a confinement domain for electrons in the channel layer (2DEG), improving the electron leakage characteristics of AlGaN / GaN HEMT devices. The confinement effect is better with increasing second nitride layer thickness; a higher 2DEG areal density results in a higher current density. However, the thickness of the second nitride layer cannot be too large; when d² is greater than a certain value... On the one hand, in the manufacturing process of devices, such as ohmic processes, source / drain ohmic contacts will encounter difficulties in manufacturing, making it difficult to form a good ohmic contact. On the other hand, an excessively thick second nitride layer can easily cause interface lattice mismatch, leading to an increase in growth defects, which in turn reduces 2DEG mobility, resulting in a decrease in overall current and a decline in RF performance.

[0033] The substrate 10 can be made of materials such as silicon carbide (SiC), sapphire, and silicon (Si). In this embodiment of the invention, the substrate 10 is a silicon carbide substrate.

[0034] The third nitride layer 3 is Al y Ga 1-y N, where 15% ≤ y ≤ 35%. The sum of the thicknesses of the first nitride layer 1 and the second nitride layer 2 is d1 + d2, where, Specifically, the second nitride layer is Al x Ga 1-x N, from the interface between the first nitride layer and the second nitride layer to the interface between the second nitride layer and the third nitride layer, the value of x gradually increases from 0 to y.

[0035] In this embodiment of the invention, the ratio of the thickness d1 of the first nitride layer 1 to the thickness d2 of the second nitride layer 2 is d1 / d2, where 17≤d1 / d2≤1000.

[0036] The sum of the thicknesses of the first nitride layer 1 and the second nitride layer 2 is within a certain range. When d1 / d2 is less than 17, meaning the thickness d1 of the first nitride layer 1 is set too small, or the thickness d2 of the second nitride layer 2 is set too large, a third nitride layer 3 (AlyGa1-yN barrier layer, y value is fixed) will grow on the second nitride layer 2. In this case, epitaxial defects may grow in the second nitride layer 2 and / or the third nitride layer, leading to excessive leakage current and poor reliability. When the thickness d1 of the first nitride layer 1 is set too small, especially when d1 is less than 17... The first nitride layer 1 has poor crystal quality, which makes it easy for defect scattering to occur between the first nitride layer 1 and the second nitride layer 2, leading to a decrease in current density. At the same time, due to the decrease in crystal quality and defects, problems such as current collapse can also be caused.

[0037] When d1 / d2 is greater than 1000, that is, the thickness d1 of the first nitride layer 1 is set too large, or the thickness d2 of the second nitride layer 2 is set too small, the current density of the device cannot be improved; similar to the traditional epitaxial structure in which an AlN insertion layer is set between the barrier layer and the channel layer, there is no over-intercalation, no effective barrier intercalation is formed, and the current density is small.

[0038] In a preferred embodiment, 35 ≤ d1 / d2 ≤ 350. Within this range, the formed nitride semiconductor device exhibits a superior current density.

[0039] In other embodiments, as shown in the appendix Figure 2 As shown, a nucleation layer 101 is further provided between the substrate 10 and the first nitride layer 1. The nucleation layer material is AlN or AlGaN. For example, an aluminum nitride nucleation layer has a thickness of [missing information]. The introduction of nucleation layer 101 forms a high-quality initial growth surface on substrate 10, providing a good foundation for subsequent epitaxial growth layers. This can significantly reduce the dislocation density of the material, improve lattice quality, and thus enhance the electron mobility, breakdown voltage, and leakage current characteristics of HEMT devices.

[0040] The epitaxial layer of the present invention further includes a cap layer 4, wherein the cap layer 4 is an unintentionally doped GaN layer, such as... Figure 3 As shown. It should be noted that the cap layer 4 serves two purposes: firstly, it protects the third nitride barrier layer from oxidation, preventing device performance degradation; secondly, it reduces surface traps, improving device performance. Specifically, along the thickness direction, the thickness of the cap layer 4 is d4, and the sum of the thicknesses of the second nitride layer, the third nitride layer, and the cap layer is d2 + d3 + d4.

[0041] The ratio of the thickness of the third nitride layer to the thickness of the second nitride layer is d3 / d2; where 2≤d3 / d2≤70.

[0042] When d3 / d2 is less than 2, meaning the thickness d3 of the third nitride layer is set too small and the thickness d2 of the second nitride layer is set too large (the insertion layer is too thick), direct tunneling (DT) and Fowler-Nordheim (FN) tunneling are easily caused. If the thickness of the third nitride layer is too small, incomplete growth and merging can easily lead to lattice defects, resulting in defect-induced tunneling (TAT). All of these tunneling effects will cause leakage current I at the gate. G Excessive size increases the risk of leakage current and affects the reliability of the device;

[0043] When d3 / d2 > 70, on the one hand, because the second nitride layer is too small, the effective increase in ΔEc caused by structural polarization is not significant, failing to generate a deeper quantum well. Consequently, electron density and mobility are not improved, resulting in a higher electron concentration, leading to a lower carrier concentration, reduced transconductance, and other RF performance degradation, such as lower gain and lower power density. On the other hand, the gate is too far from the actual two-dimensional electron gas, limiting gate control capability and increasing the source and drain leakage current I. DS Leakage current deteriorates in high-voltage applications, reducing the reliability of the device.

[0044] Furthermore, an even better solution is 5 ≤ ​​d3 / d2 ≤ 20.

[0045] In a detailed embodiment, the nitride semiconductor device comprises an AlN nucleation layer, a first nitride layer, a second nitride layer, and a third nitride layer sequentially formed on a silicon carbide substrate, wherein the thickness of the silicon carbide substrate is 500 μm, and the thickness of the AlN nucleation layer is [missing information - likely a number]. The first nitride layer is an unintentionally doped GaN layer with a thickness of [missing information]. The second nitride layer is The second nitride layer is Al. x Ga 1-x N, from the interface between the first and second nitride layers to the interface between the second and third nitride layers, x gradually increases from 0 to 0.2. The third nitride layer is Al. 0.2 Ga 0.8 N, the thickness of the third nitride layer is The AlGaN / GaN HEMT Ids-Vds curve of this invention, at Vgs = 2V, is shown below. Figure 4 As shown on the right, the leakage current diagram of the high temperature reverse bias test (HTRB) of the present invention is as follows. Figure 5 As shown on the right.

[0046] Comparative Example

[0047] A comparative example of a prior art nitride semiconductor device includes an AlN nucleation layer, an undoped GaN layer, an AlN insertion layer, and a barrier layer sequentially stacked on a silicon carbide substrate; wherein the thickness of the silicon carbide substrate is 500 μm, and the thickness of the AlN nucleation layer is [missing information - likely a number]. The thickness of the unintentionally doped GaN layer is The thickness of the AlN insertion layer is The barrier layer is Al 0.2 Ga 0.8 N, the thickness of the barrier layer The comparative AlGaN / GaN HEMT Ids-Vds curves, at Vgs = 2V, are shown below. Figure 4 As shown on the left. The comparative high-temperature reverse bias test (HTRB) leakage current diagram is shown below. Figure 5 As shown on the left, where Figure 4 In the diagram, the horizontal axis represents Vds, which is the drain voltage in volts (V), and the vertical axis represents Ids, which is the relative intensity of the drain current. Figure 5 In the graph, the horizontal axis represents stress duration in hours, and the vertical axis represents the relative intensity of drain current Ids (au). au is an abbreviation for arbitrary unit, meaning any unit, and represents relative intensity.

[0048] from Figure 4 As shown in the comparison graph of Ids-Vds for AlGaN / GaN HEMT, the current intensity of this invention is increased by 15% compared to the comparative example. From... Figure 5 As can be seen from the comparison of leakage current diagrams in the high temperature reverse bias test (HTRB), the structure of the present invention can reduce the leakage current of the high temperature reverse bias test to 1 / 10 of that in the comparative example, thereby improving the reliability of the device while increasing the current density.

[0049] Accordingly, embodiments of the present invention also provide a radio frequency (RF) amplifier, which includes a nitride semiconductor device. The RF amplifier can be applied in communication equipment such as microwave systems, radar, wireless communication modules, and network devices.

[0050] Accordingly, embodiments of the present invention also provide a communication device, which includes the aforementioned radio frequency amplifier. The communication device may be a microwave system, radar, wireless communication module, network equipment, etc.

[0051] Example 2

[0052] In Example 1, the first nitride layer is composed of an unintentionally doped GaN layer. Unlike Example 1, in this example, as... Figure 6 As shown, the first nitride layer includes a first GaN layer 11 and a second GaN layer 12 disposed on the first GaN layer 11; the second GaN layer 12 is an unintentionally doped GaN layer with a thickness ranging from [missing information]. The first GaN layer 11 is a C- or Fe-doped GaN layer, wherein the thickness is... The sum of the thicknesses of the first nitride layer 1 and the second nitride layer 2 is d1 + d2, where,

[0053] Furthermore, with a thicker first nitride layer, the electron density and mobility are improved, resulting in a higher electron concentration, less leakage current, and better device reliability.

[0054] In a preferred embodiment, 100 ≤ d1 / d2 ≤ 3000. Within this range, the resulting nitride semiconductor device exhibits superior current density, current collapse electrical characteristics, and reliability.

[0055] Furthermore, in this embodiment of the invention, a nucleation layer 101 is further provided between the substrate 10 and the first nitride layer 1. The nucleation layer material is AlN or AlGaN, as shown in the attached figure. Figure 7 As shown, a nucleation layer 101 is further provided between the substrate 10 and the first nitride layer 1. The nucleation layer material is AlN or AlGaN. For example, an aluminum nitride nucleation layer has a thickness of [missing information]. The introduction of nucleation layer 101 forms a high-quality initial growth surface on substrate 10, providing a good foundation for subsequent epitaxial growth layers. This can significantly reduce the dislocation density of the material, improve lattice quality, and thus enhance the electron mobility, breakdown voltage, and leakage current characteristics of HEMT devices.

[0056] Furthermore, in this embodiment of the invention, the epitaxial layer further includes a cap layer 4, wherein the cap layer 4 is an unintentionally doped GaN layer, such as... Figure 8As shown. It should be noted that the cap layer 4 serves two purposes: firstly, it protects the third nitride barrier layer from oxidation, preventing device performance degradation; secondly, it reduces surface traps, improving device performance. Specifically, along the thickness direction, the thickness of the cap layer 4 is d4, and the sum of the thicknesses of the second nitride layer, the third nitride layer, and the cap layer is d2 + d3 + d4.

[0057] Accordingly, embodiments of the present invention also provide a radio frequency (RF) amplifier, which includes a nitride semiconductor device. The RF amplifier can be applied in communication equipment such as microwave systems, radar, wireless communication modules, and network devices.

[0058] Accordingly, embodiments of the present invention also provide a communication device, which includes the aforementioned radio frequency amplifier. The communication device may be a microwave system, radar, wireless communication module, network equipment, etc.

[0059] In other embodiments, the third nitride layer may be In 1-z Al z N or In k Al j Ga 1-j-k N; when the third nitride layer is In 1-z Al z N, where 70 ≤ z ≤ 100%. When the third nitride layer is In k Al j Ga 1-j-k N, where 0 < k ≤ 20%, 10% ≤ j < 80%.

[0060] It should be noted that, in practical applications, the substrate of the nitride semiconductor device in the embodiments of the present invention can be further reduced in thickness through a thinning process. For example, if the silicon carbide substrate has a thickness of 500 μm, it can be further thinned to 100 μm after the nitride semiconductor device fabrication process through a thinning process.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention 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 or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention fall within the protection scope of the technical solutions of the present invention.

Claims

1. A nitride semiconductor device, comprising: a first nitride layer, the first nitride layer being a binary nitride compound; a second nitride layer disposed on the first nitride layer; the first nitride layer having opposite first and second surfaces, the second surface being an interface between the first nitride layer and the second nitride layer, a thickness direction being defined as a direction from the first surface to the second surface; the second nitride layer being composed of a first element, a second element, and a third element, the first element being an aluminum element, the second element being a nitrogen element, and the third element being a gallium element, a concentration of the first element increasing along the thickness direction; a third nitride layer disposed on the second nitride layer, the third nitride layer being a ternary nitride compound or a quaternary nitride compound; a band gap of the third nitride layer being greater than a band gap of the second nitride layer, a two-dimensional electron gas being generated in the first nitride layer; a maximum value of a concentration of the first element in the second nitride layer being less than or equal to a value of the first element in the third nitride layer; a thickness of the first nitride layer being d1, a thickness of the second nitride layer being d2, and a thickness of the third nitride layer being d3 along the thickness direction. 2.The nitride semiconductor device according to claim 1, further comprising a substrate, a nucleation layer being disposed between the substrate and the first nitride layer. 3.The nitride semiconductor device according to claim 1, further comprising a cap layer, the cap layer being an unintentionally doped GaN layer. 4.The nitride semiconductor device according to claim 3, wherein a thickness of the cap layer is d4 along the thickness direction. 5.The nitride semiconductor device according to claim 1, wherein the first element is Al, the second element is N, and the third element is Ga. 6.The nitride semiconductor device according to claim 5, wherein the first element is Al, the second element is N, and the third element is Ga. 7.The nitride semiconductor device according to claim 5, wherein the first element is Al, the second element is N, and the third element is Ga. A ratio of the thickness of the first nitride layer to the thickness of the second nitride layer is d1 / d2, wherein 17≤d1 / d2≤1000. wherein d2 < d1 ; 8.The nitride semiconductor device according to claim 7, wherein 35≤d1 / d2≤350. 9.The nitride semiconductor device according to claim 1, wherein 15%≤y≤35%; 70≤z≤100%; 0<k≤20%, 10%≤j<80%. 10.The nitride semiconductor device according to claim 1, wherein the first element is Al, the second element is N, and the third element is Ga. 11.The nitride semiconductor device according to claim 10, wherein the first element is Al, the second element is N, and the third element is Ga. 12.The nitride semiconductor device according to claim 10, wherein the first element is Al, the second element is N, and the third element is Ga. A ratio of the thickness of the third nitride layer to the thickness of the second nitride layer is d3 / d2; wherein 2≤d3 / d2≤70. The sum of the thicknesses of the second nitride layer, the third nitride layer, and the cap layer is d2+d3+d4, where 13.The nitride semiconductor device according to claim 12, wherein 100≤d1 / d2≤3000. The first nitride layer is an unintentionally doped GaN layer; wherein 14.The nitride semiconductor device according to claim 1, wherein a ratio of the thickness of the third nitride layer to the thickness of the second nitride layer is d3 / d2; wherein 2≤d3 / d2≤70. The sum of the thicknesses of the first nitride layer and the second nitride layer is d1+d2, wherein ​ ​ ​ wherein ​ ​ the third nitride layer is Al y Ga 1-y N, In 1-z Al z N or In k Al j Ga 1-j-k N; ​ ​ The first nitride layer comprises a first GaN layer, and a second GaN layer arranged on the first GaN layer; the second GaN layer is an unintentionally doped GaN layer, and the thickness range is The first GaN layer is a GaN layer doped with C or Fe, wherein ​ The sum of the thicknesses of the first nitride layer and the second nitride layer is d1+d2, wherein ​ wherein ​ ​ wherein ​ ​ ​ 15. The nitride semiconductor device according to claim 14, wherein 5 < d3 / d2 < 20.

16. A radio frequency amplifier, characterized by A nitride semiconductor device comprising any one of the nitride semiconductor devices according to claims 1 to 15.

17. A communication device, characterized by A radio frequency amplifier comprising the radio frequency amplifier according to claim 16.

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