An enhancement-mode GaN HEMT device based on RESURF electric field modulation
By introducing a p-type doped region into the AlGaN barrier layer and utilizing the RESURF effect to modulate the electric field, the problem of electric field concentration at the gate edge in traditional enhancement-mode GaN HEMT devices is solved, resulting in a significant improvement in breakdown voltage and optimization of overall performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHONGQING UNIV OF POSTS & TELECOMM
- Filing Date
- 2026-03-27
- Publication Date
- 2026-06-26
AI Technical Summary
Traditional enhancement-mode GaN HEMT devices exhibit severe electric field concentration at the gate edge, which limits the improvement of breakdown voltage and affects overall breakdown voltage performance.
By introducing p-type doped regions into the AlGaN barrier layer and utilizing the RESURF effect to introduce additional depletion regions into the barrier region, the electric field concentration at the gate edge is alleviated. By introducing p-type doped regions into the AlGaN barrier layer, a RESURF structure is formed, thereby controlling the electric field distribution.
The breakdown voltage of the device was significantly improved, increasing from 500V to 971V, an improvement of 94.2%. Furthermore, while the on-resistance increased, the power figure of merit (FOM) was significantly optimized, demonstrating superior overall withstand voltage and conductivity performance.
Smart Images
Figure CN122294530A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of semiconductor power device technology and relates to an enhancement-mode GaN HEMT device based on RESURF electric field modulation. Background Technology
[0002] An enhancement-mode gallium nitride high electron mobility transistor (E-mode GaN HEMT) is a gallium nitride-based power semiconductor device with a normally off characteristic. Unlike depletion-mode gallium nitride devices, enhancement-mode devices are off when no voltage is applied to the gate. Their operation is based on a two-dimensional electron gas (2DEG) formed by an aluminum gallium nitride / gallium nitride heterojunction structure, which exhibits extremely high electron concentration and mobility.
[0003] By introducing a p-type doped gate structure, the two-dimensional electron gas can be effectively depleted, ensuring the device remains off under zero gate voltage conditions. The increased breakdown voltage of enhancement-mode gallium nitride (Gnitride) high-electron-mobility transistors (HMTs) opens up broad application prospects in high-voltage and high-frequency power electronics. In consumer electronics, this technology can be used to develop more efficient and compact fast chargers, enabling universal fast charging for devices such as mobile phones and laptops. In the new energy vehicle sector, its high withstand voltage characteristics help improve the power density of on-board chargers and electric drive systems while reducing energy consumption.
[0004] With continuous optimization of device performance and gradual reduction in manufacturing costs, this device is expected to replace traditional silicon-based power devices on a larger scale, driving the development of power semiconductors towards higher performance and wider applications. However, in traditional device structures, there is often a severe electric field concentration phenomenon at the gate edge, which limits the further improvement of the device's breakdown voltage and thus affects the optimization of overall breakdown voltage performance. Summary of the Invention
[0005] In view of this, the purpose of the present invention is to provide an enhancement GaN HEMT device based on RESURF electric field modulation.
[0006] To achieve the above objectives, the present invention provides the following technical solution: An enhancement-mode GaN HEMT device based on RESURF electric field modulation, the device comprising: Substrate layer 11; Buffer layer 10 is located on the upper surface of the substrate layer 11; GaN channel layer 9 is located above the buffer layer 10; AlGaN barrier layer 6 is located above and in contact with the GaN channel layer 9; The source electrode 7 and the drain electrode 8 are located on both sides of the GaN channel layer 9, and both are in contact with the GaN channel layer 9 and the AlGaN barrier layer 6. p-GaN cap layer 4 is located above the AlGaN barrier layer 6; Gate 1 is located on the upper surface of the p-GaN cap layer 4; A first passivation layer 2 and a second passivation layer 3 are applied over the AlGaN barrier layer 6, with the first passivation layer 2 located between the gate 1 and the source 7, and the second passivation layer 3 located between the gate 1 and the drain 8. The AlGaN barrier layer 6 contains a p-type doped region 5, which is located below the second passivation layer 3 and between the gate 1 and the drain 8.
[0007] Furthermore, the p-GaN cap layer 4 is doped with p-type impurities at a concentration of 3.0 × 10⁻⁶. 17 cm -3 .
[0008] Furthermore, the AlGaN barrier layer 6 is doped with n-type impurities at a concentration of 1.0 × 10⁻⁶. 18 cm -3 .
[0009] Furthermore, the length of the p-type doped region 5 is 3. The thickness is 0.05. .
[0010] Furthermore, the doping concentration of the p-type doped region 5 is 1.0 × 10⁻⁶. 15 cm -3 .
[0011] Furthermore, the GaN channel layer 9 is doped with n-type impurities at a concentration of 1.0 × 10⁻⁶. 15 cm -3 .
[0012] Furthermore, the buffer layer 10 is doped with n-type impurities at a concentration of 1.0 × 10⁻⁶. 14 cm -3 .
[0013] Furthermore, the material of the buffer layer 10 is aluminum gallium nitride (AlGaN), wherein the molar composition of aluminum is 0.05.
[0014] Furthermore, the power figure of merit (FOM) of the device satisfies the following formula:
[0015] in, BV This indicates the breakdown voltage of the device. This indicates the on-resistance of the device.
[0016] The beneficial effects of this invention are as follows: (1) By introducing a p-type doped region into the AlGaN barrier layer, an additional depletion region is introduced into the barrier region using the RESURF effect. In the device off state, this structure can effectively alleviate the electric field concentration phenomenon at the gate edge, making the electric field distribution in the channel more uniform.
[0017] (2) Since the integral area enclosed by the electric field intensity curve and the horizontal axis is significantly increased, according to the positive correlation between breakdown voltage and electric field integral area, the device of the present invention can withstand a higher reverse bias voltage. Experimental simulation shows that compared with the breakdown voltage of about 500V of the conventional device, the breakdown voltage of the device of the present invention can be increased to 971V, an increase of about 94.2%.
[0018] (3) Although the introduction of this structure will lead to a slight increase in on-resistance, the FOM value of the device of the present invention is much higher than that of the conventional device, which shows better overall withstand voltage and conductivity performance.
[0019] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description
[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the structure of the enhancement-mode GaN HEMT device based on RESURF electric field modulation proposed in this invention; Figure 2 For enhancement-mode GaN HEMT devices based on RESURF electric field modulation - Output characteristic curve; Figure 3 For enhancement-mode GaN HEMT devices based on RESURF electric field modulation - Transfer characteristic curve; Figure 4Transconductance of Enhancement GaN HEMT Devices Based on RESURF Electric Field Modulation Line graph; Figure 5 Breakdown voltage of enhancement-mode GaN HEMT device based on RESURF electric field modulation Characteristic curves; Figure 6 The electron concentration distribution of the enhancement-mode GaN HEMT device based on RESURF electric field modulation under different drain-source voltages and gate voltages is shown. Figure 7 Power figure of merit for enhancement-mode GaN HEMT devices based on RESURF electric field modulation FOM Comparison chart.
[0021] Figure reference numerals: 1: Gate, 2: Left passivation layer, 3: Right passivation layer, 4: p-GaN cap layer, 5: p-type doped region, 6: AlGaN barrier layer, 7: Source, 8: Drain, 9: GaN channel layer, 10: Buffer layer, 11: Substrate layer. Detailed Implementation
[0022] The following specific examples 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. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.
[0023] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.
[0024] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and 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, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.
[0025] Example 1 This embodiment details the specific structure and parameter settings of an enhanced gallium nitride high electron mobility transistor (GaN HEMT) device based on RESURF electric field modulation with reduced surface electric field.
[0026] like Figure 1 As shown, the device is constructed sequentially from bottom to top. The bottom layer is the substrate 11, which serves as the supporting substrate for the entire epitaxial structure. A buffer layer 10 is grown on the upper surface of the substrate 11. The buffer layer 10 is made of aluminum gallium nitride (AlGaN), with an aluminum molar composition of 0.05. The electrical properties are adjusted by doping with n-type arsenic impurities, with a doping concentration set to 1.0 × 10⁻⁶. 14 cm -3 A GaN channel layer 9 is disposed above the buffer layer 10, which is also doped with n-type arsenic impurity at a doping concentration of 1.0 × 10⁻⁶. 15 cm -3 .
[0027] An AlGaN barrier layer 6 is grown above the GaN channel layer 9. This layer is doped with n-type arsenic impurity at a concentration of 1.0 × 10⁻⁶. 18 cm -3 An AlGaN barrier layer 6 and a GaN channel layer 9 form a heterojunction, generating a highly mobile two-dimensional electron gas. A p-GaN cap layer 4, doped with p-type boron impurities, is locally positioned above the AlGaN barrier layer 6. The doping concentration of this cap layer is 3.0 × 10⁻⁶. 17 cm -3 Gate 1 is deposited on the upper surface of p-GaN cap layer 4. Through the depletion effect of p-GaN cap layer 4 on the electrons in the channel below, the device achieves the normally-off characteristic, i.e., the enhancement mode.
[0028] The source 7 and drain 8 are symmetrically distributed on the left and right sides of the device, respectively, and form ohmic contacts with the GaN channel layer 9 and the AlGaN barrier layer 6. The passivation layer is divided into two parts: the left passivation layer 2 is located between the gate 1 and the source 7, and the right passivation layer 3 is located between the gate 1 and the drain 8, which are used to protect the device surface and reduce the influence of surface states.
[0029] In the core design of this embodiment, a p-type doped region 5 is introduced into the region inside the AlGaN barrier layer 6 and below the right-side passivation layer 3. The length of this p-type doped region 5 is set to 3. The thickness is set to 0.05. Its doping concentration is 1.0 × 10⁻⁶. 15 cm -3 .
[0030] Work process and principles: When the device is in the off state (gate voltage is zero or negative) and a high voltage is applied to the drain 8, the p-type doped region 5 introduces an additional depletion region in the drift region through the RESURF effect. This design changes the situation where the electric field is highly concentrated at the edge of the gate 1 in conventional devices, causing the electric field distribution to extend towards the drain. Figure 5 As shown, the breakdown voltage of the device in this embodiment reaches 971V, which is approximately 94.2% higher than the 500V of the conventional structure. Meanwhile, as... Figure 7 As shown, although the on-resistance is due to Increase to However, due to the significant difference in breakdown voltage, its power figure of merit is... FOM Significant optimization has been achieved.
[0031] Example 2 This embodiment focuses on describing the electronic transport performance of the device under different bias conditions, in order to further support the technical solution regarding electric field modulation in the claims.
[0032] Reference Figures 2 to 4 The electrical properties of the structure described in Example 1 were tested. Figure 2 As shown, because the p-type doped region 5 retains a certain depletion capability in the on-state, the effective channel thickness is slightly reduced, causing the maximum saturation current to drop to approximately [value missing]. .like Figure 3 As shown, the device's turn-on voltage stabilizes at Nearby, it maintained good enhancement characteristics.
[0033] Work process and principles: During the device turn-on phase, by applying a bias voltage greater than the turn-on voltage to gate 1, the channel beneath the p-GaN cap layer 4 resumes conduction. For example... Figure 6 As shown, in and They are respectively and Under these conditions, observation of the electron concentration distribution diagram reveals that p-type doped region 5 effectively modulates the carrier distribution between the gate and drain. Combined with... Figure 4 The transconductance curve at the gate voltage is to In between, the device with the added RESURF structure exhibited a slightly improved gate voltage control capability. This demonstrates the effectiveness of the electric field modulation scheme of this invention by precisely controlling the geometry and concentration of the p-type doped region 5 to improve breakdown voltage performance while maintaining good dynamic response characteristics to the greatest extent.
[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. An enhanced GaN HEMT device based on RESURF electric field modulation, characterized by: The device includes: Substrate (11); A buffer layer (10) is located on the upper surface of the substrate layer (11); The GaN channel layer (9) is located above the buffer layer (10); An AlGaN barrier layer (6) is located above and in contact with the GaN channel layer (9); The source (7) and drain (8) are located on both sides of the GaN channel layer (9) and are in contact with the GaN channel layer (9) and the AlGaN barrier layer (6); p-GaN cap layer (4) is located above the AlGaN barrier layer (6); The gate (1) is located on the upper surface of the p-GaN cap layer (4); A first passivation layer (2) and a second passivation layer (3) are covered above the AlGaN barrier layer (6), and the first passivation layer (2) is located between the gate (1) and the source (7), and the second passivation layer (3) is located between the gate (1) and the drain (8). The AlGaN barrier layer (6) contains a p-type doped region (5), which is located below the second passivation layer (3) and between the gate (1) and the drain (8).
2. The RESURF electric field regulated enhancement mode GaN HEMT device of claim 1, wherein: The p-GaN cap layer (4) is doped with a p-type impurity at a doping concentration of 3.0 x 1019cm-3. 17 cm -3 -3.0 x 1019cm-3.
3. The RESURF electric field regulated enhancement mode GaN HEMT device of claim 1, wherein: The AlGaN barrier layer (6) is doped with n-type impurities, with a doping concentration of 1.0 x 1018cm-3. 18 cm -3 .
4. The RESURF electric field regulated enhancement mode GaN HEMT device of claim 1, wherein: The length of the p-type doped region (5) is 3 , and the thickness is 0.05 .
5. The RESURF electric field regulated enhancement mode GaN HEMT device of claim 1, wherein: The p-type doped region (5) has a doping concentration of 1.0 x 1018cm-3 15 cm -3 -3.
6. The RESURF electric field regulated enhancement mode GaN HEMT device of claim 1, wherein: The GaN channel layer (9) is doped with n-type impurities, with a doping concentration of 1.0 x 1018cm-3. 15 cm -3 -3.
7. The enhancement-mode GaN HEMT device based on RESURF electric field modulation according to claim 1, characterized in that: The buffer layer (10) is doped with n-type impurities at a doping concentration of 1.0 x 1018 cm-3. 14 cm -3 .
8. The enhancement-mode GaN HEMT device based on RESURF electric field modulation according to claim 1, characterized in that: The material of the buffer layer (10) is aluminum gallium nitride (AlGaN), wherein the molar composition of aluminum is 0.
05.
9. The RESURF electric field regulated enhancement mode GaN HEMT device of claim 1, wherein: The power figure of merit (FOM) of the device satisfies the following formula: wherein BV represents the breakdown voltage of the device, represents the on-resistance of the device.