A P-type gate gallium nitride high electron mobility transistor

Abstract

This application relates to the field of transistor technology and provides a P-type gate gallium nitride (GaN) high electron mobility transistor. The P-type gate GaN high electron mobility transistor includes a substrate, an aluminum nitride (ANH) nucleation layer, a gallium nitride (GaN) buffer layer, an ANH barrier layer, and a passivation layer. The passivation layer contains a source, a drain, and a P-type gate structure in contact with the ANH barrier layer. The P-type gate structure includes a gate and N non-contacting GaN P-type structures. The gate is disposed on the side of the passivation layer away from the ANH barrier layer. The N GaN P-type structures are arranged sequentially along the contact surface between the passivation layer and the ANH barrier layer, and all N GaN P-type structures are embedded in the gate. The doping concentrations of the different GaN P-type structures are all different. This solution not only improves the threshold voltage of the P-type gate GaN high electron mobility transistor but also does not lead to a decrease in switching speed or an increase in switching losses.

Description

Technical Field

[0001] This application belongs to the field of transistor technology, and particularly relates to a P-type gate gallium nitride high electron mobility transistor. Background Technology

[0002] Gallium nitride (GaN) high electron mobility transistors (HEMTs) not only possess the excellent properties of GaN materials, such as large bandgap, high critical breakdown electric field, high electron saturation drift velocity, high temperature resistance, radiation resistance, and good chemical stability, but GaN materials can also form two-dimensional electron gas (2DEG) channels with high concentration and high mobility with materials such as aluminum gallium nitride (AlGaN). Therefore, GaN HEMTs are suitable for applications in high voltage, high power, and high temperature scenarios.

[0003] There are many types of GaN HEMTs, among which P-gate GaN HEMTs are widely used in high-voltage, high-power, and high-temperature applications due to their advantages such as adjustable threshold voltage and good stability. While traditional P-gate GaN HEMTs have extremely low on-resistance, their low threshold voltage makes them prone to false turn-on, limiting their application scenarios and resulting in a limited range of applicability. Currently, the main method to improve the threshold voltage of P-gate GaN HEMTs is by increasing the gate length; however, increasing the gate length leads to problems such as reduced switching speed and increased switching losses. Summary of the Invention

[0004] In view of this, embodiments of this application provide a P-gate gallium nitride high electron mobility transistor to solve the technical problem that existing methods for increasing the threshold voltage of P-gate GaN HEMTs lead to reduced switching speed and increased switching losses in P-gate GaN HEMTs.

[0005] This application provides a P-type gate gallium nitride high electron mobility transistor, including a substrate and an aluminum nitride nucleation layer, a gallium nitride buffer layer, an aluminum gallium nitride barrier layer, and a passivation layer disposed on the substrate and arranged sequentially in a direction away from the substrate; the aluminum nitride nucleation layer is in contact with the substrate, the gallium nitride buffer layer is in contact with the aluminum nitride nucleation layer, the aluminum gallium nitride barrier layer is in contact with the gallium nitride buffer layer, and the passivation layer is in contact with the aluminum gallium nitride barrier layer; the passivation layer has a source, a drain, and a P-type gate structure in contact with the aluminum gallium nitride barrier layer; the P-type gate structure includes:

[0006] The gate is disposed in the passivation layer on the side away from the aluminum gallium nitride barrier layer;

[0007] N non-contacting P-type gallium nitride structures are arranged sequentially along the contact surface between the passivation layer and the aluminum gallium nitride barrier layer, and all N P-type gallium nitride structures are embedded in the gate. The doping concentrations of the different P-type gallium nitride structures are all different.

[0008] Optionally, the P-type gate gallium nitride high electron mobility transistor further includes a two-dimensional electron gas located between the gallium nitride buffer layer and the aluminum gallium nitride barrier layer.

[0009] Optionally, different p-type gallium nitride structures have different depletion effects on the two-dimensional electron gas.

[0010] Optionally, the gate does not contact the aluminum gallium nitride barrier layer.

[0011] Optionally, the spacing between each two adjacent P-type gallium nitride structures can be adjusted.

[0012] Optionally, the length of the first side and the length of the second side of each of the P-type gallium nitride structures are adjustable; the first side is the side of the P-type gallium nitride structure parallel to the contact surface between the passivation layer and the aluminum gallium nitride barrier layer, and the second side is the side of the P-type gallium nitride structure perpendicular to the contact surface between the passivation layer and the aluminum gallium nitride barrier layer.

[0013] Optionally, the P-type gate structure further includes:

[0014] N-1 fillers are respectively filled between each pair of adjacent P-type gallium nitride structures, and the depletion effect of the fillers on the two-dimensional electron gas is weaker than the depletion effect of each P-type gallium nitride structure on the two-dimensional electron gas.

[0015] Optionally, the source electrode forms an ohmic contact with the aluminum gallium nitride barrier layer.

[0016] Optionally, the drain electrode forms an ohmic contact with the aluminum gallium nitride barrier layer.

[0017] Optionally, the N p-type gallium nitride structures form an ohmic contact with the aluminum gallium nitride barrier layer.

[0018] Implementing the P-type gate gallium nitride high electron mobility transistor provided in this application has the following beneficial effects:

[0019] The P-gate gallium nitride (GaN) high electron mobility transistor provided in this application includes a P-gate structure comprising a gate and N non-contacting GaN structures. The gate is disposed in the passivation layer on the side away from the aluminum gallium nitride (AGaN) barrier layer. The N GaN structures are arranged sequentially along the contact surface between the passivation layer and the AGaN barrier layer, and all N GaN structures are embedded in the gate. The doping concentrations of the different GaN structures are different, thus enabling the formation of channels with different threshold voltages and resistances. This gradual change in threshold voltage and resistance, compared to traditional structures, provides advantages over conventional structures. This approach achieves lower on-resistance at the same threshold voltage. Furthermore, it increases the threshold voltage of the P-gate gallium nitride (GaN) high-electron-mobility transistor (HETT). This is due to two factors: firstly, the P-gate structure effectively increases the gate thickness; secondly, the threshold voltage of the P-gate GNT is determined by the high threshold voltage. Even when the channel with a low threshold voltage is open, the P-gate GNT remains off. Due to the short-channel effect, as the threshold voltage of the high-threshold channel decreases, the overall threshold voltage decreases slowly, mitigating the tendency for the threshold voltage to decrease as the channel length shortens. Thus, this approach increases the threshold voltage of the P-gate GNT while maintaining extremely low on-resistance, without reducing switching speed or increasing switching losses. Attached Figure Description

[0020] 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.

[0021] Figure 1 A schematic diagram of a conventional P-gate GaN HEMT provided in this application embodiment;

[0022] Figure 2 This application provides a schematic diagram of the structure of a P-type gate GaN HEMT.

[0023] Figure 3 This is a schematic diagram of a P-type gate GaN HEMT provided for another embodiment of this application. Detailed Implementation

[0024] It should be noted that the terminology used in the embodiments of this application is only for explaining specific embodiments of this application and is not intended to limit this application. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, "at least one" or "one or more" means one, two or more. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0025] 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.

[0026] P-gate GaN HEMTs are heterojunction structures formed by vapor deposition or molecular beam epitaxy of an aluminum gallium nitride (AGaN) layer on a gallium nitride (GaN) layer, creating an AGaN / GaN heterojunction. Under no external stress, the positive and negative charge centers within the gallium nitride crystal separate, resulting in polarization along the polar axis—a phenomenon known as the spontaneous polarization effect of gallium nitride. Under external stress, lattice deformation causes internal charge separation, creating an electric field that induces polarization charges on the crystal surface, resulting in a piezoelectric effect. Since the piezoelectric and spontaneous polarization electric fields are in the same direction, polarization charges are induced at the heterojunction interface under the influence of the electric field. Because AGaN has a wider band gap than GaN, at equilibrium, the energy bands at the heterojunction interface bend, causing a discontinuity between the conduction and valence bands, forming a triangular potential well at the heterojunction interface. On the gallium nitride (GaN) side, the conduction band bottom is already below the Fermi level, resulting in a large accumulation of electrons in the triangular potential well. Simultaneously, the high potential barrier on the wide-bandgap AlGaN side makes it difficult for electrons to cross the potential well; they are confined to a thin layer at the interface, known as a two-dimensional electron gas (2D electron gas). The drain-source voltage generates a transverse electric field within the channel. Under the influence of this field, the 2D electron gas transports along the heterojunction interface, forming the drain output current. The gate makes a Schottky contact with the AlGaN barrier layer. By controlling the gate voltage, the depth of the potential well in the AlGaN / GaN heterojunction is controlled, altering the surface density of the 2D electron gas in the channel and thus controlling the drain output current within the channel.

[0027] Please see Figure 1 , Figure 1 This is a schematic diagram of a traditional P-gate GaN HEMT. Figure 1 As shown, this conventional P-type gate GaN HEMT may include a substrate 111, an aluminum nitride nucleation layer 112, a gallium nitride buffer layer 113, an aluminum gallium nitride barrier layer 114, a passivation layer 115, a source 116, a drain 117, a P-type gate structure 118, and a two-dimensional electron gas 119.

[0028] An aluminum nitride nucleation layer 112, a gallium nitride buffer layer 113, an aluminum gallium nitride (AGaN) barrier layer 114, and a passivation layer 115 are disposed on a substrate 111 and arranged sequentially in a direction away from the substrate 111. The aluminum nitride nucleation layer 112 is in contact with the substrate 111, the gallium nitride buffer layer 113 is in contact with the aluminum nitride nucleation layer 112, and the AGaN barrier layer 114 is in contact with the passivation layer 115. A source electrode 116, a drain electrode 117, and a P-type gate structure 118 are disposed in the passivation layer 115 and are in contact with the AGaN barrier layer 114. A two-dimensional electron gas 119 is located between the gallium nitride buffer layer 113 and the AGaN barrier layer 114. The source electrode 116 forms an ohmic contact with the AGaN barrier layer 114, the drain electrode 117 forms an ohmic contact with the AGaN barrier layer 114, and the P-type gate structure 118 forms an ohmic contact with the AGaN barrier layer 114.

[0029] While traditional P-gate GaN HEMTs possess extremely low on-resistance, their low threshold voltage makes them prone to false turn-on, limiting their application scenarios and thus their applicability. Currently, the primary method to improve the threshold voltage of traditional P-gate GaN HEMTs is by increasing the gate length. However, increasing the gate length leads to reduced switching speed and increased switching losses in traditional P-gate GaN HEMTs.

[0030] To address the technical problem that existing methods for increasing the threshold voltage of traditional P-gate GaN HEMTs lead to reduced switching speed and increased switching losses in traditional P-gate GaN HEMTs, Figure 2 The diagram shows a schematic of a P-gate GaN HEMT provided in an embodiment of this application. Compared with the traditional P-gate GaN HEMT, the P-gate GaN HEMT not only has a higher threshold voltage, but also does not lead to a decrease in switching speed or an increase in switching losses.

[0031] like Figure 2As shown, compared to the traditional P-type gate GaN HEMT, the P-type gate GaN HEMT provided in this application embodiment, in addition to including a substrate 111, an aluminum nitride nucleation layer 112, a gallium nitride buffer layer 113, an aluminum gallium nitride barrier layer 114, a passivation layer 115, a source 116, a drain 117, and a two-dimensional electron gas 119, may also include a P-type gate structure 211.

[0032] An aluminum nitride nucleation layer 112, a gallium nitride buffer layer 113, an aluminum gallium nitride (AGaN) barrier layer 114, and a passivation layer 115 are disposed on a substrate and arranged sequentially in a direction away from the substrate 111. The aluminum nitride nucleation layer 112 is in contact with the substrate 111, and the AGaN barrier layer 114 is in contact with the passivation layer 115. A source electrode 116, a drain electrode 117, and a P-type gate structure 211 are disposed in the passivation layer 115 and are in contact with the AGaN barrier layer 114. A two-dimensional electron gas 119 is located between the gallium nitride buffer layer 113 and the AGaN barrier layer 114. The source electrode 116 forms an ohmic contact with the AGaN barrier layer 114, the drain electrode 117 forms an ohmic contact with the AGaN barrier layer 114, and the P-type gate structure 211 forms an ohmic contact with the AGaN barrier layer 114.

[0033] The P-type gate structure 211 may include a gate 2111 and N non-contacting P-type gallium nitride structures 2112.

[0034] The gate 2111 is disposed in the passivation layer 115 on the side away from the aluminum gallium nitride barrier layer 114, and the gate 2111 is not in contact with the aluminum gallium nitride barrier layer 114.

[0035] N P-type gallium nitride structures 2112 are arranged sequentially along the contact surface between the passivation layer 115 and the aluminum gallium nitride barrier layer 114, and all N P-type gallium nitride structures 2112 are embedded in the gate 2111. The doping concentrations of the different P-type gallium nitride structures 2112 are all different.

[0036] In this embodiment, N is an integer greater than 1, and N can be set according to actual needs. The length of the first side of each P-type gallium nitride structure 2112, the length of the second side of each P-type gallium nitride structure 2112, the spacing between each pair of adjacent P-type gallium nitride structures 2112, and the doping concentration of each P-type gallium nitride structure 2112 can all be set according to actual needs. The first side is the side of the P-type gallium nitride structure 2112 parallel to the contact surface between the passivation layer 115 and the aluminum gallium nitride barrier layer 114; the second side is the side of the P-type gallium nitride structure 2112 perpendicular to the contact surface between the passivation layer 115 and the aluminum gallium nitride barrier layer 114.

[0037] In this embodiment, the length of the first side of each P-type gallium nitride structure 2112 refers to the distance between the start and end points of the first side of the P-type gallium nitride structure 2112. The length of the second side of each P-type gallium nitride structure 2112 refers to the distance between the start and end points of the second side of the P-type gallium nitride structure 2112. The spacing between any two adjacent P-type gallium nitride structures 2112 refers to the distance between the end point of the first side of the i-th P-type gallium nitride structure 2112 and the start point of the first side of the (i+1)-th P-type gallium nitride structure 2112. Where 1 ≤ i ≤ N-1. It can be understood that the start point of the first side of each P-type gallium nitride structure 2112 coincides with the start point of the second side.

[0038] For example, such as Figure 2 As shown, assuming the starting point of the first side and the starting point of the second side of the first P-type gallium nitride structure 2112 are both A, the ending point of the first side of the first P-type gallium nitride structure 2112 is B, and the ending point of the second side of the first P-type gallium nitride structure 2112 is C, the starting point of the first side and the starting point of the second side of the second P-type gallium nitride structure 2112 are both D, the ending point of the first side of the second P-type gallium nitride structure 2112 is E, and the ending point of the second side of the second P-type gallium nitride structure 2112 is F, and the starting point of the first side and the starting point of the second side of the third P-type gallium nitride structure 2112 are both G, then the first P-type gallium nitride structure... The length of the first side of the gallium structure 2112 is the distance between A and B; the length of the second side of the first P-type gallium nitride structure 2112 is the distance between A and C; the length of the first side of the second P-type gallium nitride structure 2112 is the distance between D and E; the length of the second side of the second P-type gallium nitride structure 2112 is the distance between D and F; the spacing between the first P-type gallium nitride structure 2112 and the second P-type gallium nitride structure 2112 is the distance between B and D; and the spacing between the second P-type gallium nitride structure 2112 and the third P-type gallium nitride structure 2112 is the distance between E and G.

[0039] In this embodiment, since the doping concentration of each P-type gallium nitride structure 2112 is different, the depletion effect of different P-type gallium nitride structures 2112 on the two-dimensional electron gas 119 is different, which can form channels with different threshold voltages and different resistances. This gradual change in threshold voltage and resistance, compared with the traditional structure, can have a lower on-resistance at the same threshold voltage. In addition, this solution can improve the threshold voltage of the P-type gate gallium nitride high electron mobility transistor. On the one hand, the P-type gate structure indirectly increases the gate thickness; on the other hand, the threshold voltage of the P-type gate gallium nitride high electron mobility transistor is determined by the high threshold voltage. After the low threshold voltage channel is turned on, the P-type gate gallium nitride high electron mobility transistor is still in the off state. Due to the short-channel effect, as the threshold voltage of the high threshold voltage channel decreases, the overall threshold voltage will slowly decrease, which can alleviate the trend of threshold voltage decrease as the channel length becomes shorter. Thus, this solution can increase the threshold voltage of the P-gate gallium nitride high electron mobility transistor while enabling it to have extremely low on-resistance. The extremely low on-resistance does not lead to a decrease in the switching speed or an increase in the switching loss of the P-gate gallium nitride high electron mobility transistor.

[0040] In addition, since all N P-type gallium nitride structures 2112 are embedded in the gate 2111, the actual contact area between the gate 2111 and the P-type gallium nitride structure 2112 is increased compared to the traditional P-type gate GaNHEMT, which can improve the gate control capability of the P-type gate gallium nitride high electron mobility transistor.

[0041] As can be seen from the above, this embodiment provides a P-gate gallium nitride (GaN) high electron mobility transistor, which is an improvement on the conventional P-gate GaN high electron mobility transistor. The P-gate structure includes a gate and N non-contacting GaN structures. The gate is disposed in the passivation layer on the side away from the aluminum gallium nitride (AGaN) barrier layer. The N GaN structures are arranged sequentially along the contact surface between the passivation layer and the AGaN barrier layer, and all N GaN structures are embedded in the gate. The doping concentrations of the different GaN structures are all different. Different doping concentrations of the GaN structures can increase the threshold voltage of the P-gate GaN high electron mobility transistor while maintaining extremely low on-resistance. Since maintaining extremely low on-resistance means that the switching speed is not reduced and the switching loss is not increased, this P-gate GaN high electron mobility transistor can solve the technical problem that existing methods for increasing the threshold voltage of P-gate GaN HEMTs lead to reduced switching speed and increased switching loss.

[0042] Please see Figure 3 , Figure 3This is a schematic diagram of a P-type gate GaN HEMT provided for another embodiment of this application. Figure 3 As shown, the P-type gate GaN HEMT provided in this embodiment and Figure 2 The difference in the provided P-type gate GaN HEMT is that the P-type gate structure in the P-type gate GaN HEMT in this embodiment may also include N-1 fillers 311, where N is an integer greater than 1.

[0043] N-1 fillers 311 are respectively filled between each two adjacent P-type gallium nitride structures 211.

[0044] Among them, the depletion effect of the N-1 fillers 311 on the two-dimensional electron gas 119 is weaker than the depletion effect of each P-type gallium nitride structure 2112 on the two-dimensional electron gas 119.

[0045] In this embodiment, N can be set according to actual needs.

[0046] As an example and not a limitation, the N-1 fillers 311 can be materials with weak depletion effects on the two-dimensional electron gas 119, such as unintentionally doped GaN or lightly doped P GaN.

[0047] In this embodiment, N-1 fillers 311 with weak depletion effects are respectively disposed between every two adjacent P-type gallium nitride structures 211. The depletion region generated by the N-1 fillers 311 with weak depletion effects can act as a buffer. When the previous channel is fully open, electrons pass through this buffer, which can homogenize the electric field of the channel below the P-type gallium nitride structure and avoid the formation of electric field peaks at the boundary of the next depletion region, thereby further improving the performance of the P-type gate gallium nitride high electron mobility transistor.

[0048] As can be seen from the above, this embodiment provides a P-type gate gallium nitride high electron mobility transistor (GaN transistor). This P-type gate GaN transistor is an improvement on the traditional P-type gate GaN transistor. The P-type gate structure includes a gate and N non-contacting P-type gallium nitride structures. The gate is disposed in the passivation layer on the side away from the aluminum gallium nitride (AGaN) barrier layer. The N P-type gallium nitride structures are arranged sequentially along the contact surface between the passivation layer and the AGaN barrier layer, and all N P-type gallium nitride structures are embedded in the gate. The doping concentration of the different P-type gallium nitride structures is different. The number of fillers is N-1, and each of the N-1 fillers is filled between every two adjacent P-type gallium nitride structures. P-type gallium nitride (GaN) structures with varying doping concentrations can maintain extremely low on-resistance while increasing the threshold voltage of P-type gate GaN high-electron-mobility transistors (HEMTs). Since maintaining extremely low on-resistance means no reduction in switching speed or increase in switching losses, this P-type gate GaN HEMT solves the technical problem that existing methods for increasing the threshold voltage of P-type gate GaN HEMTs lead to reduced switching speed and increased switching losses. Furthermore, by filling N-1 fillers between each pair of adjacent P-type GaN structures, the performance of this P-type gate GaN HEMT can be further improved.

[0049] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, refer to the relevant descriptions of other embodiments.

[0050] 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 P-gate gallium nitride high electron mobility transistor, comprising a substrate and, arranged in sequence in a direction away from the substrate, an aluminum nitride nucleation layer, a gallium nitride buffer layer, an aluminum gallium nitride barrier layer and a passivation layer; the aluminum nitride nucleation layer is in contact with the substrate, the gallium nitride buffer layer is in contact with the aluminum nitride nucleation layer, the aluminum gallium nitride barrier layer is in contact with the gallium nitride buffer layer, and the passivation layer is in contact with the aluminum gallium nitride barrier layer; the passivation layer is provided with a source, a drain and a P-gate structure in contact with the aluminum gallium nitride barrier layer; characterized in that, The P-gate structure comprises: a gate disposed in the passivation layer away from one side of the aluminum gallium nitride barrier layer; N P-type gallium nitride structures not in contact with each other, the N P-type gallium nitride structures being sequentially arranged along the contact surface of the passivation layer and the aluminum gallium nitride barrier layer, and each of the N P-type gallium nitride structures being embedded in the gate, and the doping concentrations of different P-type gallium nitride structures being different; The P-gate gallium nitride high electron mobility transistor further comprises a two-dimensional electron gas between the gallium nitride buffer layer and the aluminum gallium nitride barrier layer. The P-gate structure further comprises: N-1 fillers respectively filled between each two adjacent P-type gallium nitride structures, the fillers having a weaker depletion effect on the two-dimensional electron gas than each P-type gallium nitride structure; and the N-1 fillers being unintentionally doped gallium nitride or low-doped P-type gallium nitride.

2. The P-gate gallium nitride high electron mobility transistor of claim 1, wherein, The depletion effects of different P-type gallium nitride structures on the two-dimensional electron gas are different.

3. The P-gate gallium nitride high electron mobility transistor of claim 1, wherein, The gate is not in contact with the aluminum gallium nitride barrier layer.

4. The P-gate gallium nitride high electron mobility transistor according to any one of claims 1 to 3, wherein The source forms an ohmic contact with the aluminum gallium nitride barrier layer.

5. The P-gate gallium nitride high electron mobility transistor according to any one of claims 1 to 3, wherein The drain forms an ohmic contact with the aluminum gallium nitride barrier layer.

6. The P-gate gallium nitride high electron mobility transistor according to any one of claims 1 to 3, wherein The N P-type gallium nitride structures form an ohmic contact with the aluminum gallium nitride barrier layer.

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