GaN HEMT epitaxial structure with special high-resistance layer and preparation method of GaN HEMT epitaxial structure
By introducing alternating high-resistivity layers and delta-doped layers into the GaN HEMT epitaxial structure, the electric field distribution is optimized, solving the problem that it is difficult to grow high-concentration C-doped layers using traditional self-doping methods. This improves the breakdown voltage and breakdown voltage performance, making it suitable for high-voltage and high-power devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-09
- Publication Date
- 2026-04-07
AI Technical Summary
In traditional GaN HEMT epitaxial structures, it is difficult to grow a high concentration of C doped layer by self-doping, which limits the breakdown voltage and affects the breakdown voltage performance of the device.
A special high-resistivity layer is introduced between the transition layer and the barrier layer. By alternately stacking the high-resistivity layer and the δ-doped layer, the carbon doping concentration of the δ-doped layer is higher than that of the high-resistivity layer, thus optimizing the electric field distribution and forming a multi-layered special high-resistivity layer structure.
It significantly improves the breakdown voltage of HEMT devices, enhances their withstand voltage performance, reduces leakage current, avoids carbon doping inhomogeneity issues, and is suitable for high-voltage and high-power applications.
Smart Images
Figure CN121815707A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of GaN HEMT epitaxial structure technology, and in particular to GaN HEMT epitaxial structures with special high resistivity layers and their preparation methods. Background Technology
[0002] Traditional GaN HEMT epitaxial structures, such as Figure 1 As shown, and its self-doped carbon concentration is illustrated in the diagram below. Figure 2 As shown, since it is difficult to grow a C-doped layer with a high doping concentration on the substrate through conventional doping or self-doping methods, the breakdown voltage of existing HEMT devices is severely limited. Summary of the Invention
[0003] The purpose of this invention is to provide a GaN HEMT epitaxial structure with a special high-resistivity layer and its preparation method, which can effectively improve the breakdown voltage of the HEMT epitaxial structure and thus improve the breakdown voltage performance of the HEMT device.
[0004] To achieve the above objectives, this invention discloses a GaN HEMT epitaxial structure with a special high-resistivity layer, comprising: Substrate layer; A transition layer disposed on the substrate layer; A special high-resistivity layer is disposed in the transition layer, the special high-resistivity layer comprising at least one high-resistivity layer and at least one δ-doped layer arranged alternately in sequence, wherein the carbon doping concentration of the δ-doped layer is higher than the carbon doping concentration of the high-resistivity layer; A barrier layer is disposed on the special high-resistivity layer.
[0005] Preferably, the thickness of the high-resistivity layer ranges from 1 μm to 3 μm; and / or, the thickness of the δ-doped layer ranges from 1 nm to 10 nm.
[0006] Preferably, the carbon concentration of the high-resistivity layer is in the range of 3.0 × 10⁻⁶. 18 cm -3 ~5.0×10 18 cm -3 ; and / or, the carbon doping concentration of the δ-doped layer is greater than or equal to 7.0 × 10⁻⁶. 18 cm -3 . Preferably, the δ-doped layer is made of carbon and gallium, and the carbon doping concentration of the δ-doped layer is greater than or equal to 7.0 × 10⁻⁶. 18 cm -3 .
[0007] Preferably, the delta-doped layer includes a plurality of pointed bumps, the lateral dimensions of which range from 0.2 micrometers to 1 micrometer, and the density of the plurality of pointed bumps ranges from 1 × 10³ cm⁻¹. -2 Up to 1×105cm -2 .
[0008] Preferably, a polymer layer and / or a buffer layer are disposed between the substrate layer and the transition layer.
[0009] Preferably, an intermediate layer and / or a channel layer are disposed between the special high-resistivity layer and the barrier layer.
[0010] Preferably, the barrier layer is further provided with a capping layer and / or a passivation layer. To achieve the above objectives, this invention discloses a method for fabricating a GaN HEMT epitaxial structure with a special high-resistivity layer, comprising: Clean the substrate layer; A transition layer is grown on the substrate at a temperature range of 950°C to 1050°C. At least one high-resistivity layer and at least one δ-doped layer are sequentially and alternately grown in a temperature range of 850°C to 950°C to grow a special high-resistivity layer on the transition layer. An AlGaN barrier layer is grown on the special high-resistivity layer at a temperature range of 750°C to 850°C.
[0011] Preferably, the δ-doped layer is obtained by sequentially performing a purge growth process involving pulsed introduction of CH4 or C2H4 followed by the introduction of H2.
[0012] Compared with the prior art, the present invention provides a special high-resistivity layer between the transition layer and the barrier layer. The special high-resistivity layer includes at least one high-resistivity layer and at least one δ-doped layer arranged alternately in sequence. The carbon doping concentration of the δ-doped layer is higher than that of the high-resistivity layer. The δ-doped layer can optimize the electric field distribution to effectively improve the breakdown voltage of the HEMT epitaxial structure, thereby improving the breakdown voltage performance of the HEMT device. Attached Figure Description
[0013] Figure 1 This is a schematic diagram of an existing epitaxial structure.
[0014] Figure 2 This is a schematic diagram of the carbon concentration of existing epitaxial structures.
[0015] Figure 3 This is a schematic diagram of a GaN HEMT epitaxial structure with a special high-resistivity layer according to an embodiment of the present invention.
[0016] Figure 4This is a schematic diagram of the carbon concentration of a GaN HEMT epitaxial structure with a special high-resistivity layer according to an embodiment of the present invention. Detailed Implementation
[0017] To illustrate the technical content, structural features, objectives, and effects of the present invention in detail, the following description is provided in conjunction with the embodiments and accompanying drawings.
[0018] Please see Figure 3 and Figure 4 This invention discloses a GaN HEMT epitaxial structure with a special high-resistivity layer, comprising: Substrate 1; Transition layer 2 disposed on substrate layer 1; A special high-resistivity layer 3 is disposed on the transition layer 2. The special high-resistivity layer 3 includes at least one high-resistivity layer 31 and at least one δ-doped layer 32 arranged alternately in sequence. The carbon doping concentration of the δ-doped layer 32 is higher than that of the high-resistivity layer 31. Barrier layer 4 is set on special high-resistivity layer 3.
[0019] Compared with the prior art, the present invention provides a special high-resistivity layer 3 between the transition layer 2 and the barrier layer 4. The special high-resistivity layer 3 includes at least one high-resistivity layer 31 and at least one δ-doped layer 32 arranged alternately in sequence. The carbon doping concentration of the δ-doped layer 32 is higher than that of the high-resistivity layer 31. The δ-doped layer 32 can optimize the electric field distribution to effectively improve the breakdown voltage of the HEMT epitaxial structure, thereby improving the breakdown voltage performance of the HEMT device.
[0020] See Figure 3 and Figure 4 The thickness of the high-resistivity layer 31 ranges from 1 μm to 3 μm; and / or the thickness of the δ-doped layer 32 ranges from 1 nm to 10 nm.
[0021] Specifically, in this embodiment, both the high-resistivity layer 31 (C-GaN) and the δ-doped layer 32 are provided in multiple layers and are arranged alternately in sequence. However, it is not limited to this. In some embodiments, the δ-doped layer 32 grown and embedded in the grown high-resistivity layer 31 can also be a single-layer special δ-doped carbon layer structure.
[0022] Specifically, in some embodiments, the thickness of the special high-resistivity layer 3 is 1 μm, but it is not limited to this. See Figure 3 and Figure 4 The carbon concentration of the high-resistivity layer 31 ranges from 3.0 × 10⁻⁶. 18 cm -3 ~5.0×10 18 cm -3 ; and / or, the carbon doping concentration of the δ-doped layer 32 is greater than or equal to 7.0 × 10¹⁸ cm⁻¹. -3. Specifically, in this embodiment, one or more ultrathin high-concentration carbon doped layers are embedded in a conventional C high-resistivity layer 31 to form a special high-resistivity layer 3 with ultra-high carbon doping.
[0023] See Figure 3 and Figure 4 The δ-doped layer 32 is made of carbon and gallium (Ga), and the carbon doping concentration of the δ-doped layer 32 is greater than or equal to 7.0 × 10⁻⁶. 18 cm -3 .
[0024] Specifically, in this embodiment, such as Figure 4 As shown, spectral analysis confirms that the carbon element signal of the multi-layer special high-resistivity layer 3, which is formed by the combination of high-resistivity layer 31 (C-GaN) and δ-doped layer 32, is significantly enhanced. Furthermore, compared with the lateral breakdown voltage of HEMT devices with conventional doped or self-doped structures of ≤1200V, the lateral breakdown voltage of HEMT devices with δ-doped carbon layer structures is ≥1300V. Therefore, the breakdown voltage of this HEMT device is increased by more than 15%, and the leakage current is reduced by at least one order of magnitude. At the same time, it can effectively avoid the problem of carbon doping inhomogeneity caused by conventional self-doped structures.
[0025] contrast Figure 2 It is known that, under the same process conditions, compared with the special high-resistivity layer 3 with δ-doped structure, the breakdown voltage of the carbon-doped high-resistivity layer structure formed by self-doping effect is reduced by 15%-25%. Therefore, the present invention is applicable to 5G base stations, fast charging, electric vehicles, etc. with GaN HEMT devices equipped with high voltage and high power.
[0026] Furthermore, the δ-doped layer 32 includes a plurality of pointed bumps, the lateral dimensions of which range from 0.2 micrometers to 1 micrometer, and the density of the plurality of pointed bumps ranges from 1 × 10³ cm⁻¹. -2 Up to 1×105cm -2 .
[0027] Specifically, in this embodiment, when observing the epitaxial morphology of the special high-resistivity layer 3 formed by the δ-doped layer 32 under a microscope, multiple pointed cone-shaped black dots can be seen, but it is not limited to this.
[0028] See Figure 3 and Figure 4 A polymer layer (UGaN) and / or a buffer layer 5 are disposed between the substrate layer 1 and the transition layer 2 (GaN).
[0029] See Figure 3 and Figure 4 An intermediate layer 6 (iGaN) and / or a channel layer 7 are disposed between the special high-resistivity layer 3 and the barrier layer 4.
[0030] See Figure 3 and Figure 4 A capping layer and / or passivation layer 8 are also disposed on the barrier layer 4 (AlGaN). See Figure 3 and Figure 4 The thickness of the transition layer 2 ranges from 1 μm to 2 μm, but is not limited to this.
[0031] Please see Figure 3 and Figure 4 This invention discloses a method for fabricating a GaN HEMT epitaxial structure with a special high-resistivity layer 3, comprising: 101. Clean the substrate layer 1; Specifically, in this embodiment, substrate 1 is a sapphire substrate, but it is not limited to this.
[0032] 102. A transition layer 2 is grown on substrate 1 at a temperature range of 950℃ to 1050℃; 103. At least one high-resistivity layer 31 and at least one δ-doped layer 32 are sequentially and alternately grown in a temperature range of 850°C to 950°C, so as to grow a special high-resistivity layer 3 on the transition layer 2. Furthermore, the δ-doped layer 32 is obtained by sequentially performing a purge growth process involving pulsed introduction of CH4 or C2H4 and then H2.
[0033] Specifically, in this embodiment, during the growth stage of the high-resistivity layer 31, one or more layers of special high-resistivity layers 3 with higher concentrations are embedded on the high-resistivity layer 31 using the above-mentioned technology, which can effectively suppress the carbon tailing effect caused by self-doping.
[0034] 104. An AlGaN barrier layer 4 is grown on a special high-resistivity layer 3 at a temperature range of 750℃ to 850℃.
[0035] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.
Claims
1. A GaN HEMT epitaxial structure with a special high-resistivity layer, characterized in that, include: Substrate layer; A transition layer disposed on the substrate layer; A special high-resistivity layer is disposed in the transition layer, the special high-resistivity layer comprising at least one high-resistivity layer and at least one δ-doped layer arranged alternately in sequence, wherein the carbon doping concentration of the δ-doped layer is higher than the carbon doping concentration of the high-resistivity layer; A barrier layer is disposed on the special high-resistivity layer.
2. The GaN HEMT epitaxial structure with a special high-resistivity layer according to claim 1, characterized in that, The thickness of the high-resistivity layer ranges from 1 μm to 3 μm; and / or, the thickness of the δ-doped layer ranges from 1 nm to 10 nm.
3. The GaN HEMT epitaxial structure with a special high-resistivity layer according to claim 1, characterized in that, The carbon concentration range of the high-resistivity layer is 3.0 × 10⁻⁶. 18 cm -3 ~5.0×10 18 cm -3 ; and / or, the carbon doping concentration of the δ-doped layer is greater than or equal to 7.0 × 10⁻⁶. 18 cm -3 .
4. The GaN HEMT epitaxial structure with a special high-resistivity layer according to claim 1, characterized in that, The δ-doped layer is made of carbon and gallium, and the carbon doping concentration of the δ-doped layer is greater than or equal to 7.0 × 10⁻⁶. 18 cm -3 .
5. The GaN HEMT epitaxial structure with a special high-resistivity layer according to claim 1, characterized in that, The delta-doped layer includes a plurality of pointed bumps, the lateral dimensions of which range from 0.2 micrometers to 1 micrometer, and the density of the plurality of pointed bumps ranges from 1 × 10³ cm⁻¹. -2 Up to 1×105cm -2 .
6. The GaN HEMT epitaxial structure with a special high-resistivity layer according to claim 1, characterized in that, A polymer layer and / or a buffer layer are disposed between the substrate layer and the transition layer.
7. The GaN HEMT epitaxial structure with a special high-resistivity layer according to claim 1, characterized in that, An intermediate layer and / or a channel layer are provided between the special high-resistivity layer and the barrier layer.
8. The GaN HEMT epitaxial structure with a special high-resistivity layer according to claim 1, characterized in that, The barrier layer is further provided with a capping layer and / or a passivation layer.
9. A method for fabricating a GaN HEMT epitaxial structure with a special high-resistivity layer, characterized in that, include: Clean the substrate layer; A transition layer is grown on the substrate at a temperature range of 950°C to 1050°C. At least one high-resistivity layer and at least one δ-doped layer are sequentially and alternately grown in a temperature range of 850°C to 950°C to grow a special high-resistivity layer on the transition layer. An AlGaN barrier layer is grown on the special high-resistivity layer at a temperature range of 750°C to 850°C.
10. The method for fabricating a GaN HEMT epitaxial structure with a special high-resistivity layer according to claim 9, characterized in that, The δ-doped layer is obtained by sequentially performing a pulsed purging process involving the introduction of CH4 or C2H4 and then H2.