High electron mobility transistor, method of manufacturing the same, and electronic device
By setting an AlGaN gate barrier layer and a p-type semiconductor film layer with reduced aluminum content and thickness at the AlGaN/GaN heterojunction interface, the problem of accidental turn-on of HEMT devices is solved, normally-off operation is achieved, and the reliability and application range of the devices are improved.
Patent Information
- Application Number
- CN201910323441.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2019-04-22
- Publication Date
- 2025-11-04
- Estimated Expiration
- 2039-04-22
AI Technical Summary
Two-dimensional electron gas is easily formed at the AlGaN/GaN heterojunction interface, which makes HEMT devices prone to false turn-on and hinders their promotion in high-temperature, high-pressure, high-frequency, and high-power-density applications.
By setting an AlGaN gate barrier layer at the AlGaN/GaN heterojunction interface, reducing its aluminum content and/or thickness, the formation of two-dimensional electron gas is reduced, and the two-dimensional electron gas is further depleted by combining a p-type semiconductor film layer, thus achieving normally-off operation.
This effectively alleviates the problems of low threshold voltage and easy false turn-on of HEMT devices, realizes normally off operation, and improves the reliability and application range of the devices.
Smart Images
Figure CN111834439B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of electronics, in particular to a high electron mobility transistor, a preparation method thereof and an electronic device. BACKGROUND
[0002] GaN (gallium nitride) is one of the third generation wide band gap semiconductors, which has excellent physical properties such as wide band gap and high breakdown field. In addition, due to the spontaneous polarization and piezoelectric polarization characteristics of GaN-based semiconductors, the AlGaN (gallium aluminum nitride) / GaN heterojunction interface can generate high confinement and high concentration 2DEG (two-dimensional electron gas) under non-intentional doping. The two-dimensional electron gas has the characteristics of high electron mobility and high saturated electron drift speed.
[0003] Therefore, the AlGaN / GaN heterostructure can be used to build a HEMT (high electron mobility transistor), which can be applied to high temperature, high pressure, high frequency and high power density applications, and has good application prospects in the fields of microwave radio frequency and power electronics.
[0004] However, since the two-dimensional electron gas is easily formed at the AlGaN / GaN heterojunction interface, the HEMT is a normally-on depletion type device, which has the technical problem of easy misopening in application, hindering the popularization and application of the HEMT device. SUMMARY
[0005] The present application discloses a high electron mobility transistor for relieving the technical problems of low threshold voltage and easy misopening of the HEMT.
[0006] To achieve the above purpose, the present application provides the following technical solutions:
[0007] A high electron mobility transistor comprises:
[0008] a substrate;
[0009] a buffer layer formed on one side of the substrate;
[0010] a GaN channel layer formed on the side of the buffer layer away from the substrate, wherein the GaN channel layer comprises a gate region and a non-gate region around the gate region;
[0011] an AlGaN gate-under barrier layer formed on the side of the gate region of the GaN channel layer away from the buffer layer;
[0012] a gate electrode formed on the side of the AlGaN gate-under barrier layer away from the GaN channel layer;
[0013] An AlGaN barrier layer is formed on the non-gate area of the GaN channel layer away from the buffer layer, wherein the AlGaN barrier layer surface is formed with a source and a drain in ohmic contact with the AlGaN barrier layer;
[0014] A passivation layer covers the surface of the source, the drain, the gate electrode and the AlGaN barrier layer;
[0015] Preferably, the Al content of the AlGaN under-gate barrier layer is lower than that of the AlGaN barrier layer, and / or the thickness of the AlGaN under-gate barrier layer is smaller than that of the AlGaN barrier layer.
[0016] In the high electron mobility transistor, the GaN channel layer and the AlGaN barrier layer form a heterojunction, and due to the polarization characteristics of the GaN channel layer and the AlGaN barrier layer, a conductive two-dimensional electron gas is formed at the interface between the two. The Al content of the AlGaN under-gate barrier layer is lower than that of the AlGaN barrier layer, and / or the thickness of the AlGaN under-gate barrier layer is smaller than that of the AlGaN barrier layer, so the polarization characteristics of the AlGaN under-gate barrier layer are greatly attenuated, and the two-dimensional electron gas formed at the heterojunction interface between the AlGaN under-gate barrier layer and the GaN channel layer is greatly reduced. Therefore, in the absence of a positive voltage on the gate electrode, the two-dimensional electron gas is cut off at the AlGaN under-gate barrier layer, and the source and the drain are not easily conductive through the two-dimensional electron gas. Only when a positive voltage is applied to the gate electrode, the two-dimensional electron gas under the gate electrode is reformed, the two-dimensional electron gas is connected at the AlGaN under-gate barrier layer, and the source and the drain are conductive. In summary, in the absence of a positive voltage on the gate electrode, the high electron mobility transistor can alleviate the technical problems of low HEMT threshold voltage and easy misoperation, and realize normally-off operation.
[0017] Preferably, the thickness of the AlGaN under-gate barrier layer is 1-10 nm.
[0018] The thickness of the AlGaN barrier layer is 10-40 nm.
[0019] Preferably, the Al content of the AlGaN under-gate barrier layer is 0-20%.
[0020] The Al content of the AlGaN barrier layer is 10%-30%.
[0021] Preferably, the high electron mobility transistor further comprises a p-type semiconductor film layer, which is arranged between the gate electrode and the AlGaN under-gate barrier layer.
[0022] Preferably, the p-type semiconductor film layer comprises p-type GaN, p-type AlGaN or p-type NiO.
[0023] Preferably, a GaN repair layer is further arranged between the AlGaN barrier layer and the GaN channel layer.
[0024] The application discloses a high electron mobility transistor (HEMT) preparation method.
[0025] To achieve the above-mentioned purpose, the application provides the following technical scheme.
[0026] A high electron mobility transistor (HEMT) preparation method comprises the following steps.
[0027] A buffer layer and a GaN channel layer are sequentially formed on one side of a substrate, wherein the GaN channel layer comprises a gate region and a non-gate region around the gate region.
[0028] An AlGaN under-gate barrier layer and a gate electrode are sequentially arranged in the gate region, and an AlGaN barrier layer is formed in the non-gate region, wherein the Al content of the AlGaN under-gate barrier layer is lower than that of the AlGaN barrier layer, and / or the thickness of the AlGaN under-gate barrier layer is smaller than that of the AlGaN barrier layer.
[0029] A source electrode and a drain electrode are formed on the surface of the AlGaN barrier layer, and the AlGaN barrier layer, the source electrode and the drain electrode are annealed to form ohmic contacts between the AlGaN barrier layer and the source electrode and the drain electrode.
[0030] A passivation layer is formed on the surfaces of the source electrode, the drain electrode, the gate electrode and the AlGaN barrier layer.
[0031] The HEMT preparation method has the same advantages as the HEMT described above, and thus repeated description is omitted.
[0032] Preferably, the AlGaN under-gate barrier layer and the gate electrode are sequentially arranged in the gate region, and the AlGaN barrier layer is formed in the non-gate region.
[0033] The AlGaN under-gate barrier layer and a mask layer are sequentially and layerwisely arranged in the gate region through a patterning process.
[0034] The AlGaN barrier layer is formed on the surface of the non-gate region and the mask layer, and the mask layer and the AlGaN barrier layer on the surface of the mask layer are removed.
[0035] The gate electrode is formed on the surface of the AlGaN under-gate barrier layer away from the GaN channel layer.
[0036] Preferably, the AlGaN under-gate barrier layer and the gate electrode are sequentially arranged in the gate region, and the AlGaN barrier layer is formed in the non-gate region.
[0037] The AlGaN gate-under barrier layer, the gate electrode and the mask layer are sequentially formed in the gate region by a patterning process.
[0038] The AlGaN barrier layer is formed on the non-gate region and the surface of the mask layer, and the mask layer and the AlGaN barrier layer on the surface of the mask layer are removed.
[0039] Preferably, a GaN repair layer is formed on the non-gate region of the GaN channel layer before the AlGaN gate-under barrier layer is formed.
[0040] Preferably, the forming of the AlGaN gate-under barrier layer, the gate electrode sequentially in the gate region, and the AlGaN barrier layer in the non-gate region comprises:
[0041] The AlGaN barrier layer is formed on the side of the GaN channel layer away from the buffer layer, a hollow structure is formed on the part of the AlGaN barrier layer corresponding to the gate region, and the AlGaN gate-under barrier layer and the gate electrode are sequentially formed in the hollow structure.
[0042] Preferably, the thickness of the AlGaN gate-under barrier layer is 1-10 nm.
[0043] The thickness of the AlGaN barrier layer is 10-40 nm.
[0044] Preferably, the aluminum content of the AlGaN gate-under barrier layer is 0-20%.
[0045] The aluminum content of the AlGaN barrier layer is 10%-30%.
[0046] Preferably, a p-type semiconductor film layer is formed on the AlGaN gate-under barrier layer before the gate electrode is formed on the AlGaN gate-under barrier layer.
[0047] Preferably, the p-type semiconductor film layer comprises p-type GaN, p-type AlGaN or p-type NiO.
[0048] The application discloses an electronic device for relieving the technical problem of easy mis-opening of a HEMT.
[0049] To achieve the above object, the application provides the following technical scheme.
[0050] An electronic device comprises the high electron mobility transistor as described in the above technical scheme.
[0051] The electronic device has the same advantages as the high electron mobility transistor described above relative to the prior art, and thus will not be described here again. BRIEF DESCRIPTION OF DRAWINGS
[0052] Figure 1A structure schematic diagram of an intermediate process one in a high electron mobility transistor preparation method provided by the embodiment of the present application;
[0053] Figure 2 A structure schematic diagram of an intermediate process two in a high electron mobility transistor preparation method provided by the embodiment of the present application;
[0054] Figure 3 A structure schematic diagram of an intermediate process three in a high electron mobility transistor preparation method provided by the embodiment of the present application;
[0055] Figure 4 A structure schematic diagram of an intermediate process four in a high electron mobility transistor preparation method provided by the embodiment of the present application;
[0056] Figure 5 A structure schematic diagram of a high electron mobility transistor provided by the embodiment of the present application.
[0057] Icon: 1-substrate; 2-buffer layer; 3-GaN channel layer; 4-AlGaN gate under barrier layer; 5-p-type semiconductor film layer; 6a-GaN repair layer; 6b-GaN repair layer; 7a-AlGaN barrier layer; 7b-AlGaN barrier layer; 8-source electrode; 9-drain electrode; 10-gate electrode; 11-passivation layer; 12-mask layer. DETAILED DESCRIPTION
[0058] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.
[0059] Embodiment one
[0060] As shown in the drawings, Figure 5 The high electron mobility transistor provided by the embodiment of the present application comprises:
[0061] The substrate 1 is made of, but not limited to, Si, SiC, sapphire, AlN or GaN;
[0062] The buffer layer 2 is formed on one side of the substrate 1, and the buffer layer 2 comprises, but not limited to, GaN, AlGaN, AlGaN, AlN or a laminated structure of at least two of them. As a specific example, the thickness of the buffer layer 2 ranges from 100 nm to 6 μm, for example, 100 nm, 250 nm, 380 nm, 500 nm, 750 nm, 800 nm, 2 μm, 3 μm, 3.5 μm, 5 μm and 6 μm;
[0063] a GaN channel layer 3 formed on a side of the buffer layer 2 away from the substrate 1, wherein the GaN channel layer 3 comprises a gate region and a non-gate region around the gate region;
[0064] an AlGaN under-gate barrier layer 4 formed on a side of the gate region of the GaN channel layer 3 away from the buffer layer 2;
[0065] a gate electrode 10 formed on a side of the AlGaN under-gate barrier layer 4 away from the GaN channel layer 3;
[0066] an AlGaN barrier layer 7a formed on a side of the non-gate region of the GaN channel layer 3 away from the buffer layer 2, wherein the AlGaN barrier layer 7a is formed with a source electrode 8 and a drain electrode 9 on a surface thereof, the source electrode 8 and the drain electrode 9 being in ohmic contact with the AlGaN barrier layer 7a, the source electrode 8 comprising but not limited to Ti / Al / Ni / Au, Ti / Al / TiN / W, Ti / Al / Ti / W and Ti / TiN / W, and the drain electrode 9 comprising but not limited to Ti / Al / Ni / Au, Ti / Al / TiN / W, Ti / Al / Ti / W and Ti / TiN / W.
[0067] a passivation layer 11 covering the source electrode 8, the drain electrode 9, the gate electrode 10 and the AlGaN barrier layer 7a, the passivation layer 11 comprising but not limited to SiO, SiO2, SiN, SiON, ZrO2, HfO2, Al2O3 or a combination of any at least two of the materials;
[0068] wherein the Al content of the AlGaN under-gate barrier layer 4 is lower than the Al content of the AlGaN barrier layer 7a, and / or the thickness of the AlGaN under-gate barrier layer 4 is smaller than the thickness of the AlGaN barrier layer 7a, for example, the thickness of the AlGaN under-gate barrier layer 4 is smaller than the thickness of the AlGaN barrier layer 7a, and the Al content of the AlGaN under-gate barrier layer 4 is equal to the Al content of the AlGaN barrier layer 7a; or the thickness of the AlGaN under-gate barrier layer 4 is equal to the thickness of the AlGaN barrier layer 7a, and the Al content of the AlGaN under-gate barrier layer 4 is lower than the Al content of the AlGaN barrier layer 7a; or the Al content of the AlGaN under-gate barrier layer 4 is lower than the Al content of the AlGaN barrier layer 7a, and the thickness of the AlGaN under-gate barrier layer 4 is smaller than the thickness of the AlGaN barrier layer 7a;
[0069] In the above high electron mobility transistor, the GaN channel layer 3 and the AlGaN barrier layer 7a form a heterojunction, and due to the polarization characteristics of the GaN channel layer 3 and the AlGaN barrier layer 7a, a conductive two-dimensional electron gas is formed at the interface between the two. The Al content of the AlGaN gate-under barrier layer 4 is lower than that of the AlGaN barrier layer 7a, and / or the thickness of the AlGaN gate-under barrier layer 4 is smaller than that of the AlGaN barrier layer 7a, so the polarization characteristics of the AlGaN gate-under barrier layer 4 are greatly attenuated, and the two-dimensional electron gas formed at the heterojunction interface between the AlGaN gate-under barrier layer 4 and the GaN channel layer 3 is greatly reduced. Therefore, in the absence of a positive voltage on the gate electrode 10, the two-dimensional electron gas is cut off at the AlGaN gate-under barrier layer 4, and the source 8 and the drain 9 are not easily conductive through the two-dimensional electron gas. Only when the gate electrode 10 is supplied with a positive voltage, the two-dimensional electron gas under the AlGaN gate-under barrier layer 4 is re-generated, the two-dimensional electron gas is connected at the AlGaN gate-under barrier layer 4, and the source 8 and the drain 9 are conductive. In summary, the above high electron mobility transistor of the gate electrode 10 can alleviate the technical problem of easy mis-opening of the HEMT and realize normally-off operation.
[0070] Due to the p-type semiconductor film layer 5 and the AlGaN gate-under barrier layer 4 in the gate region of the GaN channel layer 3, the p-type semiconductor film layer 5 raises the conduction band of the heterojunction in the gate region, thereby depleting the two-dimensional electron gas under the AlGaN gate-under barrier layer 4.
[0071] Preferably, the thickness of the AlGaN gate-under barrier layer 4 is 1 nm-10 nm, for example, 1 nm, 3 nm, 5 nm, 6 nm, 8 nm, and 10 nm;
[0072] The thickness of the AlGaN barrier layer 7a is 10 nm-40 nm, for example, 10 nm, 15 nm, 20 nm, 30 nm, 35 nm, and 40 nm.
[0073] Preferably, the Al content of the AlGaN gate-under barrier layer 4 is 0-20%, for example, 0, 3%, 6%, 9%, 15%, 17%, and 20%;
[0074] The Al content of the AlGaN barrier layer 7a is 10%-30%, for example, 10%, 15%, 20%, 23%, 27%, and 30%.
[0075] In order to further deplete the two-dimensional electron gas under the AlGaN gate-under barrier layer 4, the high electron mobility transistor further comprises a p-type semiconductor film layer 5, which is arranged between the gate electrode 10 and the AlGaN gate-under barrier layer 4. The p-type semiconductor film layer 5 raises the conduction band of the heterojunction in the gate region, thereby further depleting the two-dimensional electron gas under the AlGaN gate-under barrier layer 4.
[0076] As a specific example, the p-type semiconductor film 5 includes, but is not limited to, p-type GaN, p-type AlGaN, or p-type NiO.
[0077] In addition, a GaN repair layer 6a can be provided between the AlGaN barrier layer 7a and the GaN channel layer 3. When the high electron mobility transistor in Example 1 is prepared using the high electron mobility transistor preparation method provided in Example 2, when the AlGaN gate barrier layer 4 and mask layer 12 are first formed by patterning process, the non-gate region of GaN channel layer 3 is easily damaged during etching, which affects the performance of the high electron mobility transistor.
[0078] Example 2
[0079] The high electron mobility transistor fabrication method provided in this embodiment of the invention, used to form the high electron mobility transistor provided in Embodiment 1, includes at least the following steps:
[0080] like Figure 1 As shown, a buffer layer 2 and a GaN channel layer 3 are sequentially formed on one side of the substrate 1, wherein the GaN channel layer 3 includes a gate region and a non-gate region located around the gate region;
[0081] like Figures 2 to 5 As shown, an AlGaN gate under-barrier layer 4 and a gate electrode 10 are sequentially formed in the gate region, and an AlGaN barrier layer 7a is formed in the non-gate region. The aluminum content of the AlGaN gate under-barrier layer 4 is lower than the aluminum content of the AlGaN barrier layer 7a, and / or the thickness of the AlGaN gate under-barrier layer 4 is less than the thickness of the AlGaN barrier layer 7a. For example, the thickness of the AlGaN gate under-barrier layer 4 is less than the thickness of the AlGaN barrier layer 7a, and the aluminum content of the AlGaN gate under-barrier layer 4 is equal to the aluminum content of the AlGaN barrier layer 7a; or, the thickness of the AlGaN gate under-barrier layer 4 is equal to the thickness of the AlGaN barrier layer 7a, and the aluminum content of the AlGaN gate under-barrier layer 4 is lower than the aluminum content of the AlGaN barrier layer 7a; or, the aluminum content of the AlGaN gate under-barrier layer 4 is lower than the aluminum content of the AlGaN barrier layer 7a, and the thickness of the AlGaN gate under-barrier layer 4 is less than the thickness of the AlGaN barrier layer 7a.
[0082] like Figure 4 As shown, a source 8 and a drain 9 are formed on the surface of the AlGaN barrier layer 7a, and the AlGaN barrier layer 7a, the source 8 and the drain 9 are annealed, for example, by rapid thermal annealing or laser annealing, so that the AlGaN barrier layer 7a forms ohmic contacts with the source 8 and the drain 9 respectively.
[0083] like Figure 5 As shown, a passivation layer 11 is formed covering the source electrode 8, drain electrode 9, gate electrode 10 and the surface of AlGaN barrier layer 7a.
[0084] The high electron mobility transistor (HEMT) fabricated using the above-described method has at least the following advantages: The GaN channel layer 3 and the AlGaN barrier layer 7a form a heterojunction. Due to the polarization characteristics of the GaN channel layer 3 and the AlGaN barrier layer 7a, a conductive two-dimensional electron gas is formed at the interface surface between them. Furthermore, the aluminum content of the AlGaN gate barrier layer 4 is lower than that of the AlGaN barrier layer 7a, and / or the thickness of the AlGaN gate barrier layer 4 is less than that of the AlGaN barrier layer 7a. Therefore, the polarization characteristics of the AlGaN gate barrier layer 4 are significantly reduced, and the AlGaN gate... The two-dimensional electron gas formed at the heterojunction interface between the lower barrier layer 4 and the GaN channel layer 3 is significantly reduced. Therefore, when no positive voltage is applied to the gate electrode 10, the two-dimensional electron gas is cut off at the lower barrier layer 4 of the AlGaN gate, and it is not easy for the two-dimensional electron gas to conduct between the source 8 and the drain 9. Only when a positive voltage is applied to the gate electrode 10, the two-dimensional electron gas under the lower barrier layer 4 of the AlGaN gate is regenerated, and the two-dimensional electron gas is connected at the lower barrier layer 4 of the AlGaN gate, and the source 8 and the drain 9 are energized. In summary, the above-mentioned high electron mobility transistor can alleviate the technical problems of low threshold voltage and easy false turn-on of HEMT and realize normally off operation.
[0085] The source electrode 8 and drain electrode 9 can be prepared by first depositing them on the surface of the AlGaN barrier layer 7a by electron beam evaporation, thermal evaporation or magnetron sputtering, and then forming the final structure by etching or lift-off processes. The gate electrode 10 is made of materials including but not limited to Ni / Au, and can be prepared by first depositing it on the surface of the AlGaN gate lower barrier layer 4 by electron beam evaporation, thermal evaporation or magnetron sputtering, and then forming the final structure by etching or lift-off processes.
[0086] In the gate region, an AlGaN lower gate barrier layer 4 and a gate electrode 10 are formed sequentially, and in the non-gate region, an AlGaN barrier layer 7a is formed. This can be achieved in various ways, for example:
[0087] The first form, such as Figure 1 As shown, an AlGaN gate barrier layer 4 and a mask layer 12 are sequentially stacked in the gate region through a patterning process.
[0088] like Figure 2 As shown, an AlGaN barrier layer 7a is formed on the surface of the non-gate region, and an AlGaN barrier layer 7b is formed on the surface of the mask layer 12, and as shown... Figure 3 As shown, the mask layer 12 and the AlGaN barrier layer 7b on the surface of the mask layer 12 are removed;
[0089] A gate electrode 10 is formed on the surface of the AlGaN gate lower barrier layer 4 away from the GaN channel layer 3.
[0090] In the second form, the AlGaN lower gate barrier layer 4, the gate electrode 10 and the mask layer 12 are sequentially formed in the gate region by a patterning process.
[0091] The AlGaN barrier layer 7a is formed on the surface of the non-gate region of the GaN channel layer 3, and the AlGaN barrier layer 7b is formed on the surface of the mask layer 12, and then the mask layer 12 and the AlGaN barrier layer 7b on the surface of the mask layer 12 are removed.
[0092] In order to repair the damage to the non-gate region of the GaN channel layer 3 when the AlGaN lower gate barrier layer 4 and the mask layer 12 are sequentially formed in the gate region by a patterning process, as shown in FIG. 1, a GaN repair layer 6a is formed on the non-gate region of the GaN channel layer 3 before the AlGaN lower gate barrier layer 4 is formed, and due to the deposition process, a GaN repair layer 6b is also formed on the surface of the mask layer 12 at the same time, and the GaN repair layer 6b is removed at the same time when the AlGaN barrier layer 7b and the mask layer 12 are removed. Figure 2
[0093] In the third form, the AlGaN barrier layer 7a is formed on the side of the GaN channel layer 3 away from the buffer layer 2, a hollow structure is formed in the part of the AlGaN barrier layer 7a corresponding to the gate region, and the AlGaN lower gate barrier layer 4 and the gate electrode 10 are sequentially formed in the hollow structure.
[0094] Preferably, the thickness of the AlGaN lower gate barrier layer 4 is 1 nm-10 nm, for example, 1 nm, 3 nm, 5 nm, 6 nm, 8 nm and 10 nm;
[0095] The thickness of the AlGaN barrier layer 7a is 10 nm-40 nm, for example, 10 nm, 15 nm, 20 nm, 30 nm, 35 nm and 40 nm.
[0096] Preferably, the aluminum content of the AlGaN lower gate barrier layer 4 is 0-20%, for example, 0, 3%, 6%, 9%, 15%, 17% and 20%;
[0097] The aluminum content of the AlGaN barrier layer 7a is 10%-30%, for example, 10%, 15%, 20%, 23%, 27% and 30%.
[0098] In order to further deplete the two-dimensional electron gas under the AlGaN lower gate barrier layer 4, a p-type semiconductor film layer 5 is formed on the AlGaN lower gate barrier layer 4 before the gate electrode 10 is formed on the AlGaN lower gate barrier layer 4, the p-type semiconductor lifts the conduction band of the heterojunction in the gate region, thereby further depleting the two-dimensional electron gas under the AlGaN lower gate barrier layer 4.
[0099] As a specific example, the p-type semiconductor film layer 5 includes, but is not limited to, p-type GaN, p-type AlGaN, or p-type NiO.
[0100] Embodiment three
[0101] The electronic device provided by the embodiment of the present application comprises the high electron mobility transistor provided by the embodiment one.
[0102] The electronic device includes, but is not limited to, a power supply (such as an uninterruptible power supply), a frequency converter, and a charger (such as a mobile phone fast charger and a wireless charger).
[0103] In the electronic device, the heterojunction is formed between the GaN channel layer 3 and the AlGaN barrier layer 7a, and due to the polarization characteristics of the GaN channel layer 3 and the AlGaN barrier layer 7a, a conductive two-dimensional electron gas is formed at the interface between the two. The aluminum content of the AlGaN gate-under barrier layer 4 is lower than that of the AlGaN barrier layer 7a, and / or the thickness of the AlGaN gate-under barrier layer 4 is smaller than that of the AlGaN barrier layer 7a, so the polarization characteristics of the AlGaN gate-under barrier layer 4 are greatly attenuated, and the two-dimensional electron gas formed at the heterojunction interface between the AlGaN gate-under barrier layer 4 and the GaN channel layer 3 is greatly reduced. Therefore, in the case that the gate electrode 10 is not applied with a positive voltage, the two-dimensional electron gas is cut off at the AlGaN gate-under barrier layer 4, and the source electrode 8 and the drain electrode 9 are not easily conductive through the two-dimensional electron gas. Only when the gate electrode 10 is applied with a positive voltage, the two-dimensional electron gas under the AlGaN gate-under barrier layer 4 is re-generated, the two-dimensional electron gas is connected at the AlGaN gate-under barrier layer 4, and the source electrode 8 and the drain electrode 9 are conductive. In summary, the high electron mobility transistor can alleviate the technical problem of easy mis-opening of the HEMT, and realize the normally-off operation.
[0104] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.
Claims
1. A high electron mobility transistor, characterized by, The high electron mobility transistor comprises: a substrate; a buffer layer formed on one side of the substrate; a GaN channel layer formed on the side of the buffer layer away from the substrate, wherein the GaN channel layer comprises a gate region and a non-gate region located around the gate region; an AlGaN under-gate barrier layer formed on the side of the gate region of the GaN channel layer away from the buffer layer; a gate electrode formed on the side of the AlGaN under-gate barrier layer away from the GaN channel layer; an AlGaN barrier layer formed on the side of the non-gate region of the GaN channel layer away from the buffer layer, wherein the surface of the AlGaN barrier layer is formed with a source electrode and a drain electrode in ohmic contact with the AlGaN barrier layer; a passivation layer covering the surface of the source electrode, the drain electrode, the gate electrode and the AlGaN barrier layer; wherein the aluminum content of the AlGaN under-gate barrier layer is equal to the aluminum content of the AlGaN barrier layer, and the thickness of the AlGaN under-gate barrier layer is less than the thickness of the AlGaN barrier layer; or the aluminum content of the AlGaN under-gate barrier layer is lower than the aluminum content of the AlGaN barrier layer, and the thickness of the AlGaN under-gate barrier layer is equal to the thickness of the AlGaN barrier layer; or the aluminum content of the AlGaN under-gate barrier layer is lower than the aluminum content of the AlGaN barrier layer, and the thickness of the AlGaN under-gate barrier layer is less than the thickness of the AlGaN barrier layer. The high electron mobility transistor further comprises a p-type semiconductor film layer arranged between the gate electrode and the AlGaN under-gate barrier layer; the sidewalls of the AlGaN under-gate barrier layer and the p-type semiconductor film layer are in direct contact with the AlGaN barrier layer.
2. The high electron mobility transistor of claim 1, wherein, The thickness of the AlGaN under-gate barrier layer is 1-10 nm. The thickness of the AlGaN barrier layer is 10-40 nm.
3. The high electron mobility transistor of claim 1, wherein, The aluminum content of the AlGaN under-gate barrier layer is 0-20%. The aluminum content of the AlGaN barrier layer is 10%-30%.
4. The high electron mobility transistor of claim 1, wherein, The p-type semiconductor film layer comprises p-type GaN, p-type AlGaN or p-type NiO.
5. The high electron mobility transistor of claim 1, wherein, A GaN repair layer is further arranged between the AlGaN barrier layer and the GaN channel layer.
6. A method of fabricating a high electron mobility transistor, comprising: The method comprises at least the following steps: forming a buffer layer and a GaN channel layer in sequence on one side of a substrate, wherein the GaN channel layer comprises a gate region and a non-gate region located around the gate region; forming an AlGaN under-gate barrier layer and a gate electrode in sequence on the gate region, and forming an AlGaN barrier layer on the non-gate region, wherein the aluminum content of the AlGaN under-gate barrier layer is equal to the aluminum content of the AlGaN barrier layer, and the thickness of the AlGaN under-gate barrier layer is less than the thickness of the AlGaN barrier layer; or the aluminum content of the AlGaN under-gate barrier layer is lower than the aluminum content of the AlGaN barrier layer, and the thickness of the AlGaN under-gate barrier layer is equal to the thickness of the AlGaN barrier layer; or the aluminum content of the AlGaN under-gate barrier layer is lower than the aluminum content of the AlGaN barrier layer, and the thickness of the AlGaN under-gate barrier layer is less than the thickness of the AlGaN barrier layer. A source electrode and a drain electrode are formed on the surface of the AlGaN barrier layer, and the AlGaN barrier layer, the source electrode and the drain electrode are annealed to form ohmic contacts between the AlGaN barrier layer and the source electrode and the drain electrode respectively; A passivation layer is formed on the source electrode, the drain electrode, the gate electrode and the surface of the AlGaN barrier layer; Before forming the gate electrode on the AlGaN lower gate barrier layer, a p-type semiconductor film layer is first formed on the AlGaN lower gate barrier layer.
7. The high electron mobility transistor fabrication method of claim 6, wherein, The AlGaN lower gate barrier layer and the gate electrode are sequentially formed in the gate region, and the AlGaN barrier layer is formed in the non-gate region, comprising: The AlGaN lower gate barrier layer and the mask layer are sequentially and laminatedly formed in the gate region by a patterning process; The AlGaN barrier layer is formed on the surface of the non-gate region and the mask layer, and the mask layer and the AlGaN barrier layer on the surface of the mask layer are removed. The gate electrode is formed on the surface of the AlGaN lower gate barrier layer away from the GaN channel layer.
8. The high electron mobility transistor fabrication method of claim 6, wherein, The AlGaN lower gate barrier layer and the gate electrode are sequentially formed in the gate region, and the AlGaN barrier layer is formed in the non-gate region, comprising: The AlGaN lower gate barrier layer, the gate electrode and the mask layer are sequentially and laminatedly formed in the gate region by a patterning process; The AlGaN barrier layer is formed on the surface of the non-gate region and the mask layer, and the mask layer and the AlGaN barrier layer on the surface of the mask layer are removed.
9. The method for fabricating a high electron mobility transistor according to claim 7 or 8, characterized in that, Before forming the AlGaN barrier layer, a GaN repair layer is formed in the non-gate region of the GaN channel layer.
10. The high electron mobility transistor fabrication method of claim 6, wherein, The AlGaN lower gate barrier layer and the gate electrode are sequentially formed in the gate region, and the AlGaN barrier layer is formed in the non-gate region, comprising: The AlGaN barrier layer is formed on the side of the GaN channel layer away from the buffer layer, a hollow structure is formed in the part of the AlGaN barrier layer corresponding to the gate region, and the AlGaN lower gate barrier layer and the gate electrode are sequentially formed in the hollow structure.
11. The high electron mobility transistor fabrication method of claim 6, wherein, The thickness of the AlGaN lower gate barrier layer is 1nm-10nm; The thickness of the AlGaN barrier layer is 10nm-40nm.
12. The high electron mobility transistor fabrication method of claim 6, wherein, The aluminum content of the AlGaN lower gate barrier layer is 0-20%; The aluminum content of the AlGaN barrier layer is 10%-30%.
13. The high electron mobility transistor fabrication method of claim 6, wherein, The p-type semiconductor film layer comprises a p-type GaN, a p-type AlGaN or a p-type NiO.
14. An electronic device, comprising: The high electron mobility transistor comprises any one of claims 1-5. The high electron mobility transistor comprises any one of claims 1-5.
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