Antimonide HEMT structure, epitaxial structure and preparation method

Abstract

This invention provides an antimonide HEMT structure, an epitaxial structure, and a method for preparing the same. By forming InSb channel layers on both sides of an InAs channel layer, the InSb material, due to its higher lattice constant than InAs and GaSb, exerts tensile stress on the InAs and GaSb layers on either side during growth. This improves the flatness of the interfaces between the InSb and InAs layers, and between the InSb and GaSb layers, and effectively reduces dislocation density, thereby increasing the electron mobility of the quantum well. Simultaneously, inserting a GaSb layer between the InSb and AlSb layers effectively prevents the high-temperature growth of the AlSb layer from affecting the precipitation of In atoms in the InSb and InAs layers. Furthermore, the lattice constant mismatch between the GaSb and AlSb layers is very small, further reducing dislocations and improving the quality of the active layer. Additionally, the InAs composite channel layer structure can form a stepped square quantum well, effectively increasing the concentration of 2DEG.

Description

Technical Field

[0001] This invention relates to the field of HEMT semiconductor technology, and in particular to an antimony HEMT structure, an epitaxial structure, and a method for preparing the same. Background Technology

[0002] In high-speed compound semiconductor devices, high electron mobility transistors (HEMTs) play a crucial role due to their excellent properties such as high transconductance, low threshold voltage, high current cutoff frequency, and low gate leakage current. HEMTs based on III-V compound semiconductors have received continuous attention in recent years for their application in microwave, millimeter-wave devices, monolithic integrated circuits, and logic integrated circuits.

[0003] Antimony (Sb) compound materials are used in third-generation high electron mobility transistors (HEMTs). Compared with the mainstream GaAs-based and InP-based HEMTs for high-speed devices, antimony compound HEMTs have the following advantages: 1. Sb-based HEMT materials have higher electron mobility than GaAs-based and InP-based HEMT structures, with electron mobility in the InAs channel exceeding 30,000 cm⁻¹ at room temperature. 2 V -1 s -1 2. Electrons in the conductive channel of Sb-based HEMT materials have a higher saturation drift velocity (InAs channel: 4 × 10⁻⁶). 7 The high efficiency and superior transmission performance of antimony bromide HEMTs, achieved by increasing their speed (cm / s), result in better frequency and gain characteristics, leading to higher conversion efficiency and better transmission performance under high electric fields. Furthermore, the larger conduction band discontinuity (1.35 eV) between the AlSb barrier and the InAs channel in Sb-based HEMT materials allows for higher carrier concentration in the channel, while also providing better radiation resistance. Finally, Sb-based HEMTs are directly compatible with optoelectronic devices such as lasers, LEDs, and PIN photodiodes, enabling the simultaneous fabrication of optical and electrical devices on the same chip, facilitating the realization of optoelectronic integrated circuits (OEICs). These characteristics give antimony bromide HEMTs enormous potential for achieving high frequency, high speed, low power consumption, and low noise performance at low operating voltages.

[0004] In existing antimonide HEMT structures, AlSb barrier layer and InAs channel layer are mainly grown on the substrate. Electrons form a two-dimensional electron gas (2DEG) in the InAs channel layer. Therefore, the growth quality of the channel layer is crucial to improving the performance of antimonide HEMT devices. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an antimony HEMT structure, an epitaxial structure and a method for preparing the same, in order to solve the problem of low material growth quality of the channel layer in the prior art antimony HEMT epitaxial structure.

[0006] To achieve the above and other related objectives, the present invention provides an antimony HEMT epitaxial structure, the epitaxial structure comprising:

[0007] InP substrate; and

[0008] The buffer layer, the first AlSb barrier layer, the InAs composite channel layer, the AlSb isolation layer, the second antimonide barrier layer and the InAs cap layer are arranged sequentially from bottom to top on one side of the InP substrate.

[0009] The InAs composite channel layer comprises, from bottom to top, a first GaSb channel layer, a first InSb channel layer, an InAs channel layer, a second InSb channel layer, and a second GaSb channel layer.

[0010] The thickness of the first GaSb channel layer is 1nm to 3nm, the thickness of the first InSb channel layer is 0.3nm to 1nm, the thickness of the InAs channel layer is 10nm to 12nm, the thickness of the second InSb channel layer is 0.3nm to 1nm, and the thickness of the second GaSb channel layer is 1nm to 3nm.

[0011] Optionally, a GaSb protective layer is formed between the second antimonide barrier layer and the cap layer, and the thickness of the GaSb protective layer is 2nm to 3nm.

[0012] Optionally, the second antimonide barrier layer includes, from bottom to top, a second AlSb barrier layer and an In layer. x AlSb barrier layer, where 0.2 < x < 0.3.

[0013] Optionally, the buffer layer is a composite buffer stack, comprising, from bottom to top: an InP buffer layer, a first superlattice buffer layer composed of InGaAs / InAlAs layers, and a second superlattice buffer layer composed of AlAsSb / GaSb layers; wherein the InGaAs layer composition in the first superlattice buffer layer is denoted as In x The GaAs layer has a composition of 0.65 < x < 0.75, and the InAlAs layer composition is denoted as In. y AlAs layer, 0.65 < y < 0.75; the second superlattice buffer layer includes at least two second superlattice buffer layers from bottom to top, and the molar content of As atoms in the AlAsSb layer of the second superlattice buffer layer gradually decreases along the bottom-up direction.

[0014] Furthermore, the second superlattice buffer layer comprises, from bottom to top, a lower second superlattice buffer layer, a middle second superlattice buffer layer, and an upper second superlattice buffer layer; wherein, the AlAsSb layer composition in the lower second superlattice buffer layer is denoted as AlAs. x The Sb layer has a composition of 0.35 < x < 0.45, and the AlAsSb layer composition in the middle second superlattice buffer layer is denoted as AlAs. y The Sb layer has a composition of 0.15 < y < 0.25, and the AlAsSb layer composition in the upper second superlattice buffer layer is denoted as AlAs. z Sb layer, 0 < z < 0.1.

[0015] Furthermore, the thickness of the InP buffer layer is 50nm to 100nm; the thickness of the InGaAs layer in the first superlattice buffer layer is 3nm to 5nm, the thickness of the InAlAs layer in the first superlattice buffer layer is 3nm to 5nm; the thickness of the AlAsSb layer in the second superlattice buffer layer is 5nm to 10nm, and the thickness of the GaSb layer is 2nm to 3nm.

[0016] Furthermore, the first superlattice buffer layer is composed of 5 to 10 periods of InGaAs / InAlAs layers; the second superlattice buffer layer is composed of 5 to 10 periods of AlAsSb / GaSb layers.

[0017] Optionally, the upper surface of the AlSb isolation layer is doped with tellurium δ, and the tellurium δ doping concentration is 4E12cm⁻¹. -2 ~5E12cm -2 .

[0018] This invention also provides a method for preparing an antimony compound HEMT epitaxial structure, which is prepared using molecular beam epitaxy. The preparation method includes the following steps:

[0019] S1: Provides an InP substrate;

[0020] S2: A buffer layer is grown on one side of the InP substrate;

[0021] S3: A first AlSb barrier layer is grown on the buffer layer at a growth temperature of 530℃~550℃;

[0022] S4: An InAs composite channel layer is grown on the first AlSb barrier layer, wherein the InAs composite channel layer comprises, along the growth direction, a first GaSb channel layer with a thickness of 1 nm to 3 nm, a first InSb channel layer with a thickness of 0.3 nm to 1 nm, an InAs channel layer with a thickness of 10 nm to 12 nm, a second InSb channel layer with a thickness of 0.3 nm to 1 nm, and a second GaSb channel layer with a thickness of 1 nm to 3 nm;

[0023] S5: An AlSb isolation layer is grown on the InAs composite channel layer at a growth temperature of 530℃~550℃;

[0024] S6: A second antimonide barrier layer is grown on the AlSb isolation layer;

[0025] S7: An InAs cap layer is grown on the second antimonide barrier layer at a growth temperature of 400℃~450℃.

[0026] Optionally, the method for growing the InAs composite channel layer in step S4 includes:

[0027] S41: The first GaSb channel layer is grown on the first AlSb barrier layer by a growth interruption method, and the growth temperature is 470℃~500℃.

[0028] S42: Cool down to the growth temperature of InSb and InAs materials in the Sb source atmosphere;

[0029] S43: Terminate the Sb source inlet and introduce the In source to grow the first InSb channel layer on the first GaSb channel layer using the surface mobility enhancement method.

[0030] S44: Grow the InAs channel layer on the first InSb channel layer;

[0031] S45: A second InSb channel layer is grown on the InAs channel layer using a surface mobility enhancement method;

[0032] S46: At the same growth temperature as in step S45, the second GaSb channel layer is grown on the second InSb channel layer.

[0033] Optionally, the buffer layer is a composite buffer stack, comprising, from bottom to top: an InP buffer layer, a first superlattice buffer layer composed of InGaAs / InAlAs layers, and a second superlattice buffer layer composed of AlAsSb / GaSb layers; wherein the InGaAs layer composition in the first superlattice buffer layer is denoted as In x The GaAs layer has a composition of 0.65 < x < 0.75, and the InAlAs layer composition is denoted as In.y AlAs layer, 0.65 < y < 0.75; the second superlattice buffer layer includes at least two second superlattice buffer layers sequentially from bottom to top, and the molar content of As atoms in the AlAsSb layer of the second superlattice buffer layer gradually decreases along the direction from bottom to top; the method for growing the buffer layer in step S2 includes:

[0034] S21: Raise the temperature of the InP substrate to 500℃~550℃ for deoxidation, and sequentially grow the InP buffer layer and the first superlattice buffer layer on the deoxidized InP substrate.

[0035] S22: The second superlattice buffer layer is grown on the first superlattice buffer layer at a growth temperature of 530℃~550℃.

[0036] Optionally, after forming the AlSb isolation layer in step S5, the method further includes a step of doping the upper surface of the AlSb isolation layer with tellurium δ using a GaTe source at the same temperature.

[0037] Optionally, the second antimonide barrier layer includes, from bottom to top, a second AlSb barrier layer and an In layer. x AlSb barrier layer, where 0.2 < x < 0.3; Step S6, forming the second antimonide barrier layer, includes: first growing the second AlSb barrier layer on the AlSb isolation layer at a growth temperature of 530℃~550℃; then cooling the temperature to 450℃~500℃ in the Sb source atmosphere; and finally growing the In on the second AlSb barrier layer. x AlSb barrier layer.

[0038] Furthermore, a GaSb protective layer is formed between the second antimony barrier layer and the cap layer; after the second antimony barrier layer is formed, a GaSb protective layer is formed at the same temperature in the In... x The GaSb protective layer is formed on the AlSb barrier layer.

[0039] The present invention also provides an antimonide HEMT structure, wherein the HEMT structure is prepared based on the antimonide HEMT epitaxial structure described in any of the above claims.

[0040] As described above, this invention provides an antimony HEMT structure, an epitaxial structure, and a method for preparing the same. In the antimony HEMT epitaxial structure, InSb channel layers (i.e., a first InSb channel layer and a second InSb channel layer) are formed on both sides of the InAs channel layer. Since the lattice constant of InSb material is approximately... Higher than InAs materials The lattice constant of GaSb material is approximately The InSb material layer has a high lattice constant, therefore, during the growth process, the InSb material layer will exert tensile stress on the InAs and GaSb material layers on both sides, thereby improving the flatness of the interface between the InSb and InAs material layers and between the InSb and GaSb material layers, and effectively reducing the dislocation density in the material, thus improving the electron mobility of the quantum well; at the same time, the GaSb material layer (i.e., the first GaSb channel layer and the second GaSb channel layer) on one side of the InAs material layer also plays a role in protecting the InSb channel layer and InAs channel layer during the temperature change process during growth. Because the growth temperature of AlSb is the highest (approximately 530℃~550℃), while the growth temperatures of InSb and InAs are the lowest (approximately 400℃~450℃), and the growth temperature of GaSb falls between the two (approximately 470℃~500℃), inserting a GaSb layer between the InSb and AlSb layers can effectively prevent the high-temperature growth of AlSb from affecting the precipitation of In atoms in the InSb and InAs layers, thus ensuring the quality of the channel layer. Furthermore, the lattice constant of the GaSb layer (approximately...) is... ) and the lattice constant of the AlSb material layer (approximately The mismatch is very small, which can improve the lattice matching between the two, reduce dislocations, and further improve the quality of the active layer. In addition, the InAs composite channel layer structure of the present invention can form a stepped square quantum well, thereby effectively increasing the concentration of 2DEG. Attached Figure Description

[0041] Figure 1 The diagram shown is a cross-sectional view of an antimonide HEMT epitaxial structure according to an embodiment of the present invention.

[0042] Figure 2 The diagram shown is a cross-sectional view of the InAs composite channel layer in an antimonide HEMT epitaxial structure according to an embodiment of the present invention.

[0043] Figure 3 Displayed as Figure 2 A schematic diagram of the energy band structure of the InAs composite channel layer.

[0044] Figure 4 The diagram shown is a cross-sectional view of the first superlattice buffer layer in an antimonide HEMT epitaxial structure according to an embodiment of the present invention.

[0045] Figure 5 The diagram shown is a cross-sectional view of the second superlattice buffer layer in an antimonide HEMT epitaxial structure according to an embodiment of the present invention.

[0046] Figure 6The diagram shown is a cross-sectional view of the second superlattice buffer layer in the antimonide HEMT epitaxial structure according to another embodiment of the present invention.

[0047] Figure 7 The diagram shows a flow chart of a method for preparing an antimonide HEMT epitaxial structure according to an embodiment of the present invention.

[0048] Figure 8 This diagram illustrates the shutter sequence during the growth of the InAs composite channel layer in the method for preparing an antimony HEMT epitaxial structure according to an embodiment of the present invention.

[0049] Component designation explanation

[0050] 10 InP substrate

[0051] 11 Buffer Layer

[0052] 110 InP buffer layer

[0053] 111 First Superlattice Buffer Layer

[0054] 112 InGaAs layer

[0055] 113 InAlAs layer

[0056] 114 Second superlattice buffer layer

[0057] 115 Second Superlattice Buffer Layer

[0058] 115a Lower layer second superlattice buffer layer

[0059] 115b Middle Layer Second Superlattice Buffer Layer

[0060] 115c upper second superlattice buffer layer

[0061] 116 GaSb layer

[0062] 117 AlAsSb layers

[0063] 12 First AlSb barrier layer

[0064] 13 InAs composite channel layer

[0065] 130 First GaSb Channel Layer

[0066] 131 First InSb Channel Layer

[0067] 132 InAs channel layer

[0068] 133 Second InSb Channel Layer

[0069] 134 Second GaSb Channel Layer

[0070] 14 AlSb isolation layer

[0071] 140 tellurium δ-doped

[0072] 15 Second antimonide barrier layer

[0073] 150 Second AlSb barrier layer

[0074] 151 In x AlSb barrier layer

[0075] 16 GaSb protective layer

[0076] 17 InAs cap layer Detailed Implementation

[0077] 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 also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0078] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0079] It should be understood that the use of terms such as "first," "second," and "third" to define the components is merely for the purpose of distinguishing the aforementioned components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0080] Please see Figures 1 to 8It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0081] like Figure 1 and Figure 2 As shown, this embodiment provides an antimonide HEMT epitaxial structure, the epitaxial structure comprising:

[0082] InP substrate 10; and

[0083] The buffer layer 11, the first AlSb barrier layer 12, the InAs composite channel layer 13, the AlSb isolation layer 14, the second antimonide barrier layer 15 and the InAs cap layer 17 are arranged sequentially from bottom to top on one side of the InP substrate 10.

[0084] Among them, such as Figure 2 As shown, the InAs composite channel layer 13 includes, from bottom to top, a first GaSb channel layer 130, a first InSb channel layer 131, an InAs channel layer 132, a second InSb channel layer 133, and a second GaSb channel layer 134.

[0085] The thickness of the first GaSb channel layer 130 is 1nm to 3nm, the thickness of the first InSb channel layer 131 is 0.3nm to 1nm, the thickness of the InAs channel layer 132 is 10nm to 12nm, the thickness of the second InSb channel layer 133 is 0.3nm to 1nm, and the thickness of the second GaSb channel layer 134 is 1nm to 3nm.

[0086] In antimonide HEMT epitaxial structures, InAs channel layers grown on AlSb barrier layers relax more easily because the lattice constant of InAs is approximately [value missing]. The lattice constant of AlSb material is approximately The significant lattice mismatch between the two materials easily leads to a deterioration in the interface quality of the InAs / AlSb quantum well, and generates mismatch dislocations within the InAs channel layer. Interface roughness and these mismatch dislocations, acting as typical sources of electron scattering, severely affect the electron mobility of the quantum well. In the antimonide HEMT epitaxial structure of this embodiment, InSb channel layers (i.e., a first InSb channel layer and a second InSb channel layer) are formed on both sides of the InAs channel layer. Since the lattice constant of InSb material is approximately... Higher than InAs materials The lattice constant of GaSb material is approximately The InSb material layer has a high lattice constant, therefore, during the growth process, the InSb material layer will exert tensile stress on the InAs and GaSb material layers on both sides, thereby improving the flatness of the interface between the InSb and InAs material layers and between the InSb and GaSb material layers, and effectively reducing the dislocation density in the material, thus improving the electron mobility of the quantum well; at the same time, the GaSb material layer (i.e., the first GaSb channel layer and the second GaSb channel layer) on one side of the InAs material layer also plays a role in protecting the InSb channel layer and InAs channel layer during the temperature change process during growth. Because the growth temperature of AlSb is the highest (approximately 530℃~550℃), while the growth temperatures of InSb and InAs are the lowest (approximately 400℃~450℃), and the growth temperature of GaSb falls between the two (approximately 470℃~500℃), inserting a GaSb layer between the InSb and AlSb layers can effectively prevent the high-temperature growth of AlSb from affecting the precipitation of In atoms in the InSb and InAs layers, thus ensuring the quality of the channel layer. Furthermore, the lattice constant of the GaSb layer (approximately...) is... ) and the lattice constant of the AlSb material layer (approximately The mismatch is very small, which can improve the lattice matching between the two, reduce dislocations, and further improve the quality of the active layer; in addition, the InAs composite channel layer structure of this embodiment can form such as Figure 3 The stepped square quantum well shown effectively increases the concentration of 2DEG.

[0087] like Figure 1 As shown, in a preferred example, a GaSb protective layer 16 is formed between the second antimonide barrier layer 15 and the cap layer 17, and the thickness of the GaSb protective layer 16 is 2nm to 3nm. The GaSb protective layer 16 can protect the InAs / AlSb HEMT structure from the influence of the cavity growth environment, and facilitate the cooling during the growth of the cap layer InAs material; in addition, the GaSb protective layer 16 can also provide some stress relief on the second antimonide barrier layer 15 to improve the mobility of the HEMT device; finally, the GaSb protective layer 16 can also serve as an etching stop layer during the fabrication of the HEMT device to facilitate the etching of the gate trench.

[0088] like Figure 1 As shown, as a specific example, the second antimonide barrier layer 15 includes, from bottom to top, a second AlSb barrier layer 150 and an In layer 150. x AlSb barrier layer 151, where 0.2 < x < 0.3. The In layer located above is increased. xThe AlSb barrier layer 151 can reduce the problems caused by the oxidation of the second AlSb barrier layer 150 during the subsequent fabrication of HEMT devices; in addition, the In x The AlSb barrier layer 151 can also serve as a hole blocking layer, reducing gate leakage current caused by hole leakage, making the device more suitable for ultra-low power device applications. The thickness of the second AlSb barrier layer 150 is typically chosen to be 10nm to 15nm. x The thickness of the AlSb barrier layer 151 is generally chosen to be 3nm to 5nm.

[0089] like Figure 1 As shown, as another specific example, the upper surface of the AlSb isolation layer 14 is doped with tellurium δ-doped 140, and the doping concentration of the tellurium δ-doped 140 is 4E12cm⁻¹. -2 ~5E12cm -2 Tellurium δ-doping 140 avoids the amphoteric doping properties of Si dopants and allows for a higher carrier concentration. The thickness of the AlSb isolation layer is typically chosen to be 3nm to 5nm.

[0090] As an example, the InAs cap layer 17 is typically heavily N-type doped. Its main function is to facilitate the formation of a good ohmic contact with the subsequently formed metal lead-out structure, thereby reducing contact resistance, lowering the threshold voltage, and reducing device power consumption. The N-type heavy doping of the InAs cap layer 17 can be achieved through silicon doping, with a silicon doping concentration typically around 0.5E19cm⁻¹. -3 ~1.0E19cm -3 The thickness of the InAs cap layer 17 is generally selected to be 20nm to 30nm.

[0091] As an example, the thickness of the first AlSb barrier layer 12 is typically 100 nm to 200 nm. The first AlSb barrier layer 12 serves as both a lower barrier layer and a buffer layer to further adjust and alleviate the lattice mismatch problem between the InP substrate 10 and the InAs channel layer 132.

[0092] like Figure 1 , Figure 4 and Figure 5 As shown, in a preferred example, the buffer layer 11 is a composite buffer stack, comprising, from bottom to top: an InP buffer layer 110, a first superlattice buffer layer 111 composed of InGaAs / InAlAs layers, and a second superlattice buffer layer 114 composed of AlAsSb / GaSb layers; wherein, as Figure 4 As shown, the composition of the InGaAs layer 112 in the first superlattice buffer layer 111 is denoted as In. xThe GaAs layer has a x-value of 0.65 < x < 0.75, and the InAlAs layer 113 is denoted as In. y AlAs layer, 0.65 < y < 0.75; such as Figure 5 As shown, the second superlattice buffer layer 114 includes at least two second superlattice buffer layers 115 sequentially from bottom to top, and the molar content of As atoms in the AlAsSb layer 117 of the second superlattice buffer layer 115 gradually decreases along the bottom-up direction. The InP buffer layer 110 can make the surface of the deoxidized InP substrate 10 flat; the first superlattice buffer layer 111 can compensate for the lattice mismatch between the InP substrate 10 and the active region, pulling the lattice constant to a certain value. The InAlAs layer 113 is positioned between InAs and InP, and it also provides a high resistivity, improving substrate leakage. The second superlattice buffer layer 114 is configured with a gradually decreasing molar content of As atoms in the AlAsSb layer from bottom to top, further compensating for the lattice mismatch between the InP substrate 10 and the active region, and pulling the lattice constant to the same level as the AlSb material (approximately). This gradually compensates for the lattice mismatch between the substrate and the active region, improving the material growth quality of the active region. Furthermore, the AlAsSb layer 117 can provide a higher resistivity, mitigating substrate leakage. It should be noted that during the cycling cycle of the first superlattice buffer layer 111, the stacking positions of the InGaAs layer 112 and the InAlAs layer 113 are not excessively restricted; they can be arranged as follows: Figure 4 The InGaAs layer 112 shown is located at the bottom layer, and the InAlAs layer 113 is located at the top layer. Alternatively, the InAlAs layer 113 can be located at the bottom layer, and the InGaAs layer 112 can be located at the top layer. In this embodiment, it is preferred to... Figure 4 The InGaAs layer 112 shown is located at the bottom layer, and the InAlAs layer 113 is located at the top layer. Additionally, during the cycle of the second superlattice buffer layer 114, the AlAsSb layer 117 is located at the top layer, and the GaSb layer 116 is located at the bottom layer.

[0093] More preferably, such as Figure 6 As shown, the second superlattice buffer layer 114 has three second superlattice sub-buffer layers 115 arranged from bottom to top, that is... Figure 6The lower second superlattice buffer layer 115a, the middle second superlattice buffer layer 115b, and the upper second superlattice buffer layer 115c have the following variations in the molar content of As atoms in the AlAsSb layer 117: The composition of the AlAsSb layer 117 in the lower second superlattice buffer layer 115a is denoted as AlAs. x The Sb layer has a composition of 0.35 < x < 0.45, and the AlAsSb layer 117 in the middle second superlattice buffer layer 115b is denoted as AlAs. y The Sb layer has a composition of 0.15 < y < 0.25, and the AlAsSb layer 117 in the upper second superlattice buffer layer 115c is denoted as AlAs. z Sb layer, 0 < z < 0.1.

[0094] Further, the InP buffer layer 110 has a thickness of 50 nm to 100 nm; the InGaAs layer 112 in the first superlattice buffer layer 111 has a thickness of 3 nm to 5 nm, the InAlAs layer 113 in the first superlattice buffer layer 111 has a thickness of 3 nm to 5 nm; the AlAsSb layer 117 in the second superlattice buffer layer 115 has a thickness of 5 nm to 10 nm, and the GaSb layer 116 has a thickness of 2 nm to 3 nm.

[0095] Preferably, the first superlattice buffer layer 111 is composed of 5 to 10 periods of InGaAs layer 112 / InAlAs layer 113; the second superlattice buffer layer 115 is composed of 5 to 10 periods of AlAsSb layer 117 / GaSb layer 116.

[0096] This embodiment also provides a method for preparing an antimony HEMT epitaxial structure, used to prepare the antimony HEMT epitaxial structure described above. Figure 7 This is a schematic flowchart of the method for preparing the antimony compound HEMT epitaxial structure in this embodiment, which is prepared using molecular beam epitaxy. Figure 1 To obtain the antimonide HEMT epitaxial structure using this preparation method, the preparation method includes the following steps:

[0097] S1: Provides an InP substrate;

[0098] S2: A buffer layer is grown on one side of the InP substrate;

[0099] S3: A first AlSb barrier layer is grown on the buffer layer at a growth temperature of 530℃~550℃;

[0100] S4: An InAs composite channel layer is grown on the first AlSb barrier layer, wherein the InAs composite channel layer comprises, along the growth direction, a first GaSb channel layer with a thickness of 1 nm to 3 nm, a first InSb channel layer with a thickness of 0.3 nm to 1 nm, an InAs channel layer with a thickness of 10 nm to 12 nm, a second InSb channel layer with a thickness of 0.3 nm to 1 nm, and a second GaSb channel layer with a thickness of 1 nm to 3 nm;

[0101] S5: An AlSb isolation layer is grown on the InAs composite channel layer at a growth temperature of 530℃~550℃;

[0102] S6: A second antimonide barrier layer is grown on the AlSb isolation layer;

[0103] S7: An InAs cap layer is grown on the second antimonide barrier layer at a growth temperature of 400℃~450℃.

[0104] Specifically, the InP substrate 10 in step S1 includes, but is not limited to, indium phosphide substrates of 2 inches, 4 inches, 6 inches, and 8 inches, as well as composite substrates composed of silicon-based indium phosphide. Furthermore, before proceeding to step S2, the InP substrate 10 undergoes a temperature-induced deoxidation treatment.

[0105] As an example, such as Figure 1 , Figure 4 and Figure 5 As shown, the buffer layer 11 is a composite buffer stack, comprising, from bottom to top: an InP buffer layer 110, a first superlattice buffer layer 111 composed of an InGaAs layer 112 / InAlAs layer 113, and a second superlattice buffer layer 114 composed of an AlAsSb layer 117 / GaSb layer 116; wherein, the InGaAs layer 112 in the first superlattice buffer layer 111 is denoted as In x The GaAs layer has a x-value of 0.65 < x < 0.75, and the InAlAs layer 113 is denoted as In. y AlAs layer, 0.65 < y < 0.75; the second superlattice buffer layer 114 includes at least two second superlattice buffer layers 115 sequentially from bottom to top, and the molar content of As atoms in the AlAsSb layer 117 of the second superlattice buffer layer 115 gradually decreases along the bottom-up direction; at this time, the method of growing the buffer layer 11 in step S2 includes:

[0106] S21: Raise the temperature of the InP substrate 10 to 500℃~550℃ for deoxidation, and sequentially grow the InP buffer layer 110 and the first superlattice buffer layer 111 on the deoxidized InP substrate 10.

[0107] S22: The second superlattice buffer layer 114 is grown on the first superlattice buffer layer 111 at a growth temperature of 530℃~550℃.

[0108] As an example, such as Figure 1 As shown, after forming the AlSb isolation layer 14 in step S5, the method further includes a step of performing tellurium δ doping 140 on the upper surface of the AlSb isolation layer 14 using a GaTe source at the same temperature.

[0109] As an example, the second antimonide barrier layer 15 includes, from bottom to top, a second AlSb barrier layer 150 and an In layer 150. x AlSb barrier layer 151, where 0.2 < x < 0.3; Step S6, forming the second antimonide barrier layer 15, includes: first growing the second AlSb barrier layer 150 on the AlSb isolation layer 14 at a growth temperature of 530℃ to 550℃; then cooling the temperature to 450℃ to 500℃ in the Sb source atmosphere; and finally growing the In on the second AlSb barrier layer 150. x AlSb barrier layer 151. Further, when a GaSb protective layer 16 is formed between the second antimonide barrier layer 15 and the cap layer 17, the In... x Following the AlSb barrier layer 151, there is also an In layer at the same temperature. x The step of forming the GaSb protective layer on the AlSb barrier layer 151.

[0110] As a preferred example, the method for growing the InAs composite channel layer in step S4 includes:

[0111] S41: The first GaSb channel layer 130 is grown on the first AlSb barrier layer 12 by a growth interruption method, and the growth temperature is 470℃~500℃.

[0112] S42: Cool down to the growth temperature of InSb and InAs materials in the Sb source atmosphere;

[0113] S43: Terminate the Sb source inlet and introduce the In source to grow the first InSb channel layer 131 on the first GaSb channel layer 130 using the surface mobility enhancement method.

[0114] S44: Grow the InAs trench layer 132 on the first InSb trench layer 131;

[0115] S45: The second InSb trench layer 133 is grown on the InAs trench layer 132 using the surface mobility enhancement method;

[0116] S46: At the same growth temperature as in step S45, the second GaSb channel layer 134 is grown on the second InSb channel layer 133.

[0117] Specifically, such as Figure 8 The diagram shown illustrates the shutter sequence during the growth of the InAs composite channel layer in step S4. (Combined with...) Figure 2 and Figure 8 ,in:

[0118] The time period a is the growth time of the first AlSb barrier layer 12, and the specific growth time is determined according to the thickness and growth rate.

[0119] Time period b is the growth time of the first GaSb channel layer 130. During this process, the Sb source is continuously introduced, and the growth temperature is first reduced from the growth temperature of the first AlSb barrier layer 12 in time period a (e.g., 530℃~550℃) to the suitable temperature for GaSb material growth (e.g., 470℃~500℃). Then, the Ga source is introduced to generate the first GaSb channel layer 130.

[0120] The time period c is the temperature change time (i.e. cooling time) for the subsequent growth of the first InSb channel layer 131 and the InAs channel layer 132 materials, during which the Sb source is continuously introduced.

[0121] The time period d is the growth time of the first InSb channel layer 131 grown using the surface mobility enhancement (MEE) method, which can effectively suppress the mixing of group V elements.

[0122] e is the growth time of the InAs channel layer 132. The specific growth time is determined according to the thickness and growth rate. The growth temperature of the InAs channel layer 132 is the same as the growth temperature of the first InSb channel layer 131.

[0123] The time period f is the growth time of the second InSb channel layer 133 grown using the surface mobility enhancement (MEE) method, which can effectively suppress the intermixing of group V elements.

[0124] The time period g is the growth time of the second GaSb channel layer 134. During this process, the growth temperature can be kept the same as the growth temperature of the second InSb channel layer 133. The second GaSb channel layer 134 can effectively prevent the segregation of In in the In-containing channel layer.

[0125] The time period h is the temperature change time during which the temperature rises to the suitable temperature for AlSb material growth under an atmosphere continuously supplied with Sb source.

[0126] The i-th time period is the growth time of the AlSb isolation layer 14, and the specific growth time is determined according to the thickness and growth rate.

[0127] This embodiment also provides an antimonide HEMT structure, which is prepared based on the antimonide HEMT epitaxial structure described in this embodiment.

[0128] In summary, this invention provides an antimonide HEMT structure, an epitaxial structure, and a method for preparing the same. In the antimonide HEMT epitaxial structure, InSb channel layers (i.e., a first InSb channel layer and a second InSb channel layer) are formed on both sides of the InAs channel layer. Since the lattice constant of InSb material is approximately... Higher than InAs materials The lattice constant of GaSb material is approximately The InSb material layer has a high lattice constant, therefore, during the growth process, the InSb material layer will exert tensile stress on the InAs and GaSb material layers on both sides, thereby improving the flatness of the interface between the InSb and InAs material layers and between the InSb and GaSb material layers, and effectively reducing the dislocation density in the material, thus improving the electron mobility of the quantum well; at the same time, the GaSb material layer (i.e., the first GaSb channel layer and the second GaSb channel layer) on one side of the InAs material layer also plays a role in protecting the InSb channel layer and InAs channel layer during the temperature change process during growth. Because the growth temperature of AlSb is the highest (approximately 530℃~550℃), while the growth temperatures of InSb and InAs are the lowest (approximately 400℃~450℃), and the growth temperature of GaSb falls between the two (approximately 470℃~500℃), inserting a GaSb layer between the InSb and AlSb layers can effectively prevent the high-temperature growth of AlSb from affecting the precipitation of In atoms in the InSb and InAs layers, thus ensuring the quality of the channel layer. Furthermore, the lattice constant of the GaSb layer (approximately...) is... ) and the lattice constant of the AlSb material layer (approximately The mismatch is very small, which can improve the lattice matching between the two, reduce dislocations, and further improve the quality of the active layer. In addition, the InAs composite channel layer structure of the present invention can form a stepped square quantum well, thereby effectively increasing the concentration of 2DEG. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0129] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. An antimony compound HEMT epitaxial structure, characterized in that, The epitaxial structure includes: InP substrate; and The buffer layer, the first AlSb barrier layer, the InAs composite channel layer, the AlSb isolation layer, the second antimonide barrier layer and the InAs cap layer are arranged sequentially from bottom to top on the InP substrate. The InAs composite channel layer comprises, from bottom to top, a first GaSb channel layer, a first InSb channel layer, an InAs channel layer, a second InSb channel layer, and a second GaSb channel layer. The thickness of the first GaSb channel layer is 1nm~3nm, the thickness of the first InSb channel layer is 0.3nm~1nm, the thickness of the InAs channel layer is 10nm~12nm, the thickness of the second InSb channel layer is 0.3nm~1nm, and the thickness of the second GaSb channel layer is 1nm~3nm.

2. The antimonide HEMT epitaxial structure according to claim 1, characterized in that: A GaSb protective layer is formed between the second antimonide barrier layer and the cap layer, and the thickness of the GaSb protective layer is 2nm~3nm.

3. The antimony compound HEMT epitaxial structure according to claim 1, characterized in that: The second antimonide barrier layer includes, from bottom to top, a second AlSb barrier layer and an In layer. x AlSb barrier layer, where 0.2 < x < 0.

3.

4. The antimony compound HEMT epitaxial structure according to claim 1, characterized in that, The buffer layer is a composite buffer stack, comprising, from bottom to top: an InP buffer layer, a first superlattice buffer layer composed of InGaAs / InAlAs layers, and a second superlattice buffer layer composed of AlAsSb / GaSb layers; wherein the InGaAs layer composition in the first superlattice buffer layer is denoted as In x The GaAs layer has a composition of 0.65 < x < 0.75, and the InAlAs layer composition is denoted as In. y AlAs layer, 0.65 < y < 0.75; the second superlattice buffer layer includes at least two second superlattice buffer layers from bottom to top, and the molar content of As atoms in the AlAsSb layer of the second superlattice buffer layer gradually decreases along the bottom-up direction.

5. The antimonide HEMT epitaxial structure according to claim 4, characterized in that: The second superlattice buffer layer comprises, from bottom to top, a lower second superlattice buffer layer, a middle second superlattice buffer layer, and an upper second superlattice buffer layer; wherein, the AlAsSb layer composition in the lower second superlattice buffer layer is denoted as AlAs. x The Sb layer has a composition of 0.35 < x < 0.45, and the AlAsSb layer composition in the middle second superlattice buffer layer is denoted as AlAs. y The Sb layer has a chromaticity of 0.15 < y < 0.

25. The AlAsSb layer composition in the upper second superlattice buffer layer is denoted as AlAs. z Sb layer, 0 < z < 0.

1.

6. The antimonide HEMT epitaxial structure according to claim 4 or 5, characterized in that: The InP buffer layer has a thickness of 50nm~100nm; the InGaAs layer in the first superlattice buffer layer has a thickness of 3nm~5nm, the InAlAs layer in the first superlattice buffer layer has a thickness of 3nm~5nm; the AlAsSb layer in the second superlattice buffer layer has a thickness of 5nm~10nm, and the GaSb layer has a thickness of 2nm~3nm.

7. The antimony compound HEMT epitaxial structure according to claim 6, characterized in that: The first superlattice buffer layer consists of 5 to 10 periods of InGaAs / InAlAs layers; the second superlattice buffer layer consists of 5 to 10 periods of AlAsSb / GaSb layers.

8. The antimony compound HEMT epitaxial structure according to claim 1, characterized in that: The upper surface of the AlSb isolation layer is doped with tellurium δ, and the doping concentration of tellurium δ is 4E12cm. -2 ~5E12cm -2 .

9. A method for preparing an antimony compound HEMT epitaxial structure, characterized in that, The preparation method, which employs molecular beam epitaxy, includes the following steps: S1: Provides an InP substrate; S2: A buffer layer is grown on the InP substrate; S3: A first AlSb barrier layer is grown on the buffer layer at a growth temperature of 530℃~550℃; S4: An InAs composite channel layer is grown on the first AlSb barrier layer, wherein the InAs composite channel layer comprises, along the growth direction, a first GaSb channel layer with a thickness of 1 nm to 3 nm, a first InSb channel layer with a thickness of 0.3 nm to 1 nm, an InAs channel layer with a thickness of 10 nm to 12 nm, a second InSb channel layer with a thickness of 0.3 nm to 1 nm, and a second GaSb channel layer with a thickness of 1 nm to 3 nm; S5: An AlSb isolation layer is grown on the InAs composite channel layer at a growth temperature of 530℃~550℃; S6: A second antimonide barrier layer is grown on the AlSb isolation layer; S7: An InAs cap layer is grown on the second antimonide barrier layer at a growth temperature of 400℃~450℃.

10. The method for preparing the antimony compound HEMT epitaxial structure according to claim 9, characterized in that, Step S4, the method for growing the InAs composite channel layer, includes: S41: The first GaSb channel layer is grown on the first AlSb barrier layer by a growth interruption method, and the growth temperature is 470℃~500℃. S42: Cool down to the growth temperature of InSb and InAs materials in the Sb source atmosphere; S43: Terminate the Sb source inlet and introduce the In source to grow the first InSb channel layer on the first GaSb channel layer using the surface mobility enhancement method. S44: Grow the InAs channel layer on the first InSb channel layer; S45: A second InSb channel layer is grown on the InAs channel layer using a surface mobility enhancement method; S46: At the same growth temperature as in step S45, the second GaSb channel layer is grown on the second InSb channel layer.

11. The method for preparing the antimony compound HEMT epitaxial structure according to claim 9, characterized in that, The buffer layer is a composite buffer stack, comprising, from bottom to top: an InP buffer layer, a first superlattice buffer layer composed of InGaAs / InAlAs layers, and a second superlattice buffer layer composed of AlAsSb / GaSb layers; wherein the InGaAs layer composition in the first superlattice buffer layer is denoted as In x The GaAs layer has a composition of 0.65 < x < 0.75, and the InAlAs layer composition is denoted as In. y AlAs layer, 0.65 < y < 0.75; the second superlattice buffer layer includes at least two second superlattice buffer layers sequentially from bottom to top, and the molar content of As atoms in the AlAsSb layer of the second superlattice buffer layer gradually decreases along the direction from bottom to top; the method for growing the buffer layer in step S2 includes: S21: Raise the temperature of the InP substrate to 500℃~550℃ for deoxidation, and sequentially grow the InP buffer layer and the first superlattice buffer layer on the deoxidized InP substrate. S22: The second superlattice buffer layer is grown on the first superlattice buffer layer at a growth temperature of 530℃~550℃.

12. The method for preparing the antimony compound HEMT epitaxial structure according to claim 9, characterized in that: After forming the AlSb isolation layer in step S5, the method further includes a step of doping the upper surface of the AlSb isolation layer with tellurium δ using a GaTe source at the same temperature.

13. The method for preparing the antimony compound HEMT epitaxial structure according to claim 9, characterized in that, The second antimonide barrier layer includes, from bottom to top, a second AlSb barrier layer and an In layer. x AlSb barrier layer, where 0.2 < x < 0.3; Step S6, forming the second antimonide barrier layer, includes: first growing the second AlSb barrier layer on the AlSb isolation layer at a growth temperature of 530℃~550℃; then cooling the temperature to 450℃~500℃ in the Sb source atmosphere; and finally growing the In on the second AlSb barrier layer. x AlSb barrier layer.

14. The method for preparing the antimony compound HEMT epitaxial structure according to claim 13, characterized in that, A GaSb protective layer is formed between the second antimony barrier layer and the cap layer; after the formation of the second antimony barrier layer, a GaSb protective layer is formed at the same temperature in the In... x The GaSb protective layer is formed on the AlSb barrier layer.

15. An antimony compound HEMT structure, characterized in that: The HEMT structure is prepared based on the antimonide HEMT epitaxial structure according to any one of claims 1 to 8.

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