Heterojunction quantum well and preparation method thereof

Abstract

The invention provides a heterojunction quantum well and a preparation method thereof, and the method comprises the steps: providing a substrate, and forming a heterojunction quantum well at one side of the substrate through a chemical vapor deposition method; the heterojunction quantum well comprises a first barrier layer, a quantum well layer and a second barrier layer which are stacked in sequence, the first barrier layer is located between the quantum well layer and the substrate, the first barrier layer and the second barrier layer are both made of germanium-silicon, when the heterojunction quantum well is a silicon heterojunction quantum well, the quantum well layer is a silicon quantum well layer, and when the heterojunction quantum well is a silicon quantum well layer, the second barrier layer is a silicon quantum well layer. When the heterojunction quantum well is a germanium heterojunction quantum well, the quantum well layer is a germanium quantum well layer; in the process of forming the heterojunction quantum well, the precursor is decomposed in a target temperature range, and a product obtained through decomposition is deposited on one side of the substrate to obtain the heterojunction quantum well; the precursor is subjected to multi-stage reaction during decomposition, and the target temperature range is 300-550 DEG C; the interface quality of the heterojunction quantum well can be greatly improved, the surface roughness of the film layer can be reduced, and high-quality preparation of the heterojunction quantum well is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor, in particular to a heterojunction quantum well and a preparation method thereof. BACKGROUND

[0002] Heterojunction quantum wells (such as silicon heterojunction quantum wells or germanium heterojunction quantum wells) have wide application potential in large-scale integration of quantum wells due to their excellent material performance. At present, in the preparation of heterojunction quantum wells, high-temperature conditions are mainly used. However, high-temperature processes can cause the following problems: increased surface roughness; under high-temperature conditions, surface atom diffusion is enhanced, which is easy to form a rough interface structure, thereby affecting the performance stability of the quantum well. Interface defect problem: high temperature can easily introduce interface stress and defects, thereby reducing the quality of the heterojunction interface and affecting the mobility of carriers. Limited material selection: certain low-temperature sensitive materials are unstable at high temperatures, which limits the design freedom of the heterojunction. Process complexity: high-temperature growth requires special equipment and strict environmental control, which increases the manufacturing cost. Therefore, it is currently an urgent technical problem to provide a heterojunction quantum well preparation method that can improve the interface quality. SUMMARY

[0003] Therefore, the purpose of the present application is to provide a heterojunction quantum well and a preparation method thereof, which can greatly improve the interface quality of the heterojunction quantum well, reduce the surface roughness of the film layer, and achieve high-quality preparation of the heterojunction quantum well. The specific scheme is as follows:

[0004] In one aspect, the present application provides a preparation method of a heterojunction quantum well, comprising:

[0005] providing a substrate;

[0006] forming a heterojunction quantum well on one side of the substrate by chemical vapor deposition; the heterojunction quantum well comprises a first barrier layer, a quantum well layer and a second barrier layer stacked in sequence, the first barrier layer is located between the quantum well layer and the substrate, and the materials of the first barrier layer and the second barrier layer are both germanium silicon; when the heterojunction quantum well is a silicon heterojunction quantum well, the quantum well layer is a silicon quantum well layer; and when the heterojunction quantum well is a germanium heterojunction quantum well, the quantum well layer is a germanium quantum well layer.

[0007] In the process of forming the heterojunction quantum well, a precursor is decomposed in a target temperature range, and the product obtained by decomposition is deposited on one side of the substrate to obtain the heterojunction quantum well; the precursor undergoes multi-stage reactions during decomposition, and the target temperature range is 300°C ~ 550°C.

[0008] In a possible implementation, the precursor includes a silicon-based precursor and a germanium-based precursor, the germanium-based precursor includes Ge2H6, and the silicon-based precursor includes Si2H6; in the process of forming the heterojunction quantum well, in the target temperature range, the Ge2H6 is decomposed to obtain GeH4, the Si2H6 is decomposed to obtain SiH4, and the GeH4 reacts with the SiH4 to form the heterojunction quantum well.

[0009] In a possible implementation, the germanium-based precursor further includes Ge3H8, and the silicon-based precursor further includes Si3H8; in the process of forming the heterojunction quantum well, in the target temperature range, the Ge3H8 is decomposed to obtain Ge2H6, and the Si3H8 is decomposed to obtain Si2H6.

[0010] In a possible implementation, the silicon-based precursor further includes dichlorodihydrogen silicon, and in the process of forming the first barrier layer and / or the second barrier layer, the dichlorodihydrogen silicon is introduced into a reaction chamber and reacts with the germanium-based precursor.

[0011] In a possible implementation, when the heterojunction quantum well is a germanium heterojunction quantum well and the substrate is a silicon substrate, before forming the first barrier layer, a first buffer layer is generated by decomposing the precursor in the target temperature range, and a material of the first buffer layer is Si 1-x Ge x In the direction in which the substrate points to the first barrier layer, the content of Ge in the first buffer layer gradually decreases.

[0012] In a possible implementation, the first buffer layer is generated by decomposing the precursor and HCl in the target temperature range.

[0013] In a possible implementation, before forming the first buffer layer, a germanium layer located on one side of the substrate is generated by decomposing the precursor in the target temperature range.

[0014] In a possible implementation, when the heterojunction quantum well is a silicon heterojunction quantum well and the substrate is a silicon substrate, before forming the first barrier layer, a second buffer layer is generated by decomposing the precursor in the target temperature range, and a material of the second buffer layer is Si 1-x Ge x In the direction in which the substrate points to the first barrier layer, the content of Ge in the second buffer layer gradually increases.

[0015] In a possible implementation, the second buffer layer is generated by decomposition of the precursor and HCl in the target temperature range.

[0016] In a possible implementation, an annealing process is performed in a temperature range of 550°C ~ 950°C before forming the first barrier layer.

[0017] In a possible implementation, HCl is circulated to participate in the reaction during formation of the heterojunction quantum well.

[0018] In a possible implementation, a cap layer is formed on the side of the second barrier layer away from the quantum well layer by decomposition of the precursor in the target temperature range, and the material of the cap layer is silicon or germanium.

[0019] In another aspect, the embodiments of the present application further provide a heterojunction quantum well, comprising:

[0020] a substrate;

[0021] a heterojunction quantum well on one side of the substrate; the heterojunction quantum well comprises a first barrier layer, a quantum well layer and a second barrier layer stacked in sequence, the first barrier layer is between the quantum well layer and the substrate, and the materials of the first barrier layer and the second barrier layer are both germanium silicon; when the heterojunction quantum well is a silicon heterojunction quantum well, the quantum well layer is a silicon quantum well layer; and when the heterojunction quantum well is a germanium heterojunction quantum well, the quantum well layer is a germanium quantum well layer.

[0022] The embodiments of the present application provide a heterojunction quantum well and a preparation method thereof. A substrate is provided, and a heterojunction quantum well is formed on one side of the substrate by a chemical vapor deposition method. The heterojunction quantum well comprises a first barrier layer, a quantum well layer and a second barrier layer stacked in sequence. The first barrier layer is between the quantum well layer and the substrate. The materials of the first barrier layer and the second barrier layer are both germanium silicon. When the heterojunction quantum well is a silicon heterojunction quantum well, the quantum well layer is a silicon quantum well layer. When the heterojunction quantum well is a germanium heterojunction quantum well, the quantum well layer is a germanium quantum well layer. During formation of the heterojunction quantum well, a precursor is decomposed in a target temperature range. The product obtained by decomposition of the precursor is deposited on one side of the substrate to obtain the heterojunction quantum well. The precursor undergoes multi-stage reactions during decomposition. The target temperature range is 300°C ~ 550°C. In this way, the quantum well is prepared by using the precursor capable of undergoing multi-stage reactions during decomposition. These precursors can be considered as high-molecular-weight precursors. They are more completely decomposed in a low-temperature environment of 300°C ~ 550°C, and the decomposition rate is faster. Therefore, the interface quality of the heterojunction quantum well can be greatly improved. Each film layer tends to be generated in a two-dimensional plane rather than a three-dimensional island, the surface roughness of the film layer can be reduced, and the heterojunction quantum well can be prepared in high quality. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic flowchart of a method for fabricating a heterojunction quantum well according to an embodiment of this application is shown;

[0025] Figure 2 A schematic diagram of a germanium heterojunction quantum well provided in an embodiment of this application is shown;

[0026] Figure 3 This paper shows a schematic diagram of the structure of a silicon heterojunction quantum well provided in an embodiment of this application;

[0027] Figure 4 A schematic diagram illustrating the decomposition process of a precursor provided in an embodiment of this application is shown;

[0028] Figure 5 This illustration shows a process for forming a Ge heterojunction quantum well according to an embodiment of this application;

[0029] Figure 6 This illustration shows a process for forming a Si heterojunction quantum well according to an embodiment of this application. Detailed Implementation

[0030] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0031] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0032] Secondly, this application provides a detailed description in conjunction with schematic diagrams. When detailing the embodiments of this application, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of this application. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0033] As described in the background, at present, in the preparation of heterojunction quantum wells, high-temperature conditions are mainly adopted. However, high-temperature processes can cause the following problems: increased surface roughness: under high-temperature conditions, surface atom diffusion is enhanced, which is easy to form a rough interface structure, thereby affecting the performance stability of the quantum well. Interface defect problem: high temperature is easy to introduce interface stress and defects, thereby reducing the quality of the heterojunction interface and affecting the mobility of the carriers. Limited material selection: certain low-temperature sensitive materials are unstable at high temperature, which limits the design freedom of the heterojunction. Process complexity: high-temperature growth requires special equipment and strict environmental control, increasing the manufacturing cost.

[0034] Based on the above technical problems, the embodiments of the present application provide a heterojunction quantum well and a preparation method thereof. A substrate is provided, and a heterojunction quantum well is formed on one side of the substrate by a chemical vapor deposition method. The heterojunction quantum well includes a first barrier layer, a quantum well layer, and a second barrier layer stacked in sequence. The first barrier layer is located between the quantum well layer and the substrate. The materials of the first barrier layer and the second barrier layer are both germanium silicon. When the heterojunction quantum well is a silicon heterojunction quantum well, the quantum well layer is a silicon quantum well layer. When the heterojunction quantum well is a germanium heterojunction quantum well, the quantum well layer is a germanium quantum well layer. During the formation of the heterojunction quantum well, the precursor is decomposed in a target temperature range, and the product obtained by the decomposition is deposited on one side of the substrate to obtain the heterojunction quantum well. The precursor undergoes multi-stage reactions during decomposition, and the target temperature range is 300°C-550°C. In this way, the quantum well is prepared using the precursor that can undergo multi-stage reactions during decomposition. These precursors can be considered as high-molecular-weight precursors. Their decomposition is more complete and the decomposition rate is faster in a low-temperature environment of 300°C-550°C, thereby greatly improving the interface quality of the heterojunction quantum well, making the film layers more inclined to form two-dimensional planes rather than three-dimensional island growth, reducing the surface roughness of the film layers, and achieving high-quality preparation of the heterojunction quantum well.

[0035] For ease of understanding, the heterojunction quantum well and the preparation method thereof provided by the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0036] Reference Figure 1 As shown in the figure, a flowchart of a preparation method of a heterojunction quantum well provided by the embodiments of the present application is shown. The method can include the following steps.

[0037] S101, providing a substrate 101;

[0038] S102, forming a heterojunction quantum well on one side of the substrate 101 by a chemical vapor deposition method; the heterojunction quantum well comprises a first barrier layer 104, a quantum well layer 105 and a second barrier layer 106 which are stacked in sequence, the first barrier layer 104 is located between the quantum well layer 105 and the substrate 101, the materials of the first barrier layer 104 and the second barrier layer 106 are both germanium silicon, when the heterojunction quantum well is a silicon heterojunction quantum well, the quantum well layer 105 is a silicon quantum well layer 105, when the heterojunction quantum well is a germanium heterojunction quantum well, the quantum well layer 105 is a germanium quantum well layer 105; in the process of forming the heterojunction quantum well, a precursor is decomposed in a target temperature range, and a product obtained by the decomposition is deposited on one side of the substrate 101 to obtain the heterojunction quantum well; the precursor undergoes multi-stage reactions in the decomposition, and the target temperature range is 300°C-550°C.

[0039] Specifically, the substrate 101 can be a silicon substrate 101, a germanium substrate 101, a silicon-on-insulator (SOI) substrate 101 or a germanium-on-insulator (GeOI) substrate 101, and can also be other substrates 101.

[0040] The heterojunction quantum well can be formed on the substrate 101 by a chemical vapor deposition (CVD) method, which can also be reduced pressure chemical vapor deposition (RP-CVD) or ultra-high vacuum chemical vapor deposition (UHVCVD).

[0041] The heterojunction quantum well comprises a first barrier layer 104, a quantum well layer 105 and a second barrier layer 106 which are stacked in sequence from bottom to top, and the first barrier layer 104 is closer to the substrate 101. When the thickness of the quantum well layer 105 is thinned to the order of the Bohr radius or the De Broglie wavelength, the quantum size effect appears, at which time the carriers are confined in the potential well formed by the quantum well layer 105, and the potential well is called a quantum well. The quantum well layer 105 is a narrow-bandgap ultrathin layer, which is sandwiched between two wide-bandgap barrier thin layers, which can be called the first barrier layer 104 and the second barrier layer 106, and the barrier layer can also be called a barrier layer.

[0042] When the heterojunction quantum well is a silicon heterojunction quantum well, the quantum well layer 105 is a silicon quantum well layer 105, at this time the quantum well layer 105 can be denoted as Si QW, and when the heterojunction quantum well is a germanium heterojunction quantum well, the quantum well layer 105 is a germanium quantum well layer 105, at this time the quantum well layer 105 can be denoted as Ge QW. Referring to Figure 2 Fig. 2 shows a structure schematic diagram of a germanium heterojunction quantum well provided by an embodiment of the present application, and Fig. 3 shows a structure schematic diagram of a silicon heterojunction quantum well provided by an embodiment of the present application. Figure 3As shown, a structure diagram of a silicon heterojunction quantum well provided by an embodiment of the present application.

[0043] The material in the two barrier layers can both be silicon germanium (Si 1-x Ge x ), in which the content of germanium is fixed, i.e., the composition is fixed. As an example, when the heterojunction quantum well is a germanium heterojunction quantum well, x is in a range of 65% to 95% to ensure that the barrier layer and the germanium quantum well layer 105 can be more matched to reduce dislocations, and when the heterojunction quantum well is a silicon heterojunction quantum well, x is in a range of 10% to 40%, at which time the content of silicon in the barrier layer is relatively high to ensure that the barrier layer and the silicon quantum well layer 105 can be more matched to reduce dislocations.

[0044] Specifically, in the process of forming the heterojunction quantum well by using the CVD method, the precursor can be decomposed in a target temperature range, and the product obtained by the decomposition can be deposited on the surface of the substrate 101, so as to gradually form various film layers, such as the barrier layer and the quantum well layer 105, to obtain the final heterojunction quantum well.

[0045] It is worth noting that the precursor is a precursor capable of undergoing multi-stage reactions during decomposition, such as Ge2H6, which is first decomposed into GeH4 during the decomposition process, and GeH4 is further decomposed into Ge, that is, Ge2H6 undergoes a two-stage reaction. Such precursors capable of undergoing multi-stage reactions can be considered as high molecular weight precursors. Moreover, in the deposition process, the temperature in the chamber is in a target temperature range, and the target temperature range is a relatively low temperature range, specifically 300°C to 550°C. In this way, the precursors capable of undergoing multi-stage reactions are decomposed in a low-temperature environment, and these precursors have a relatively low decomposition temperature and a relatively high deposition speed, so that uniform deposition of various film layers can be achieved, and the surface quality of the film layers is higher.

[0046] In summary, the quantum well is prepared by using such precursors capable of undergoing multi-stage reactions during decomposition, which can be considered as high molecular weight precursors. They are more completely decomposed in a low-temperature environment of 300°C to 550°C, and the decomposition rate is faster, so that the interface quality of the heterojunction quantum well can be greatly improved, various film layers can be more inclined to be generated in a two-dimensional plane rather than in a three-dimensional island, the surface roughness of the film layers can be reduced, high-quality heterojunction quantum wells can be prepared, and the influence of high-temperature processes on the interface roughness and stress defects is effectively avoided.

[0047] Furthermore, in practical applications, by utilizing the decomposition characteristics of high molecular weight precursors and controlling the deposition rate and reaction atmosphere, the atomic arrangement on the film surface can be optimized, achieving interface smoothing and further reducing surface roughness. The growth quality of the film can be further improved by adjusting the flow rate of the carrier gas (e.g., H2), the pressure range of the chamber (e.g., 0.1-100 torr), and the reaction time. Additionally, the thickness of the quantum well layer 105 can be controlled within 20 nm, for example, 4-20 nm, thereby effectively confining charge carriers within the quantum well and ensuring quantum effects. During the deposition process, gas purging technology can also be used to introduce a low-flow-rate inert gas (e.g., argon) to purge the surface, removing excess reaction products and further reducing surface roughness.

[0048] In one possible implementation, the precursor may include a silicon-based precursor and a germanium-based precursor. The germanium-based precursor may include Ge2H6, and the silicon-based precursor may include Si2H6. During the formation of the heterojunction quantum well, within a target temperature range, Ge2H6 decomposes to obtain GeH4, and Si2H6 decomposes to obtain SiH4. GeH4 and SiH4 react to form the heterojunction quantum well.

[0049] In other words, silicon-based precursors are used to provide silicon, and germanium-based precursors are used to provide germanium. When the silicon-based precursor includes Si₂H₆ and the germanium-based precursor includes Ge₂H₆, refer to... Figure 4 The diagram shown illustrates the decomposition process of a precursor according to an embodiment of this application. Under low-temperature conditions, Ge₂H₆ can decompose to obtain GeH₄, and Si₂H₆ can decompose to obtain SiH₄. GeH₄ and SiH₄ react to form various films, such as Si, on the substrate 101. 1-x Ge x The fabrication of heterojunction quantum wells is achieved by using material layers such as Si2H6, Ge2H6, and Si. Since Si2H6 and Ge2H6 can be completely decomposed through a second-order reaction, the film deposition rate can be greatly accelerated, and the second-order reaction is easier to control, reducing the difficulty of film growth.

[0050] In one possible implementation, the germanium-based precursor may further include Ge3H8, and the silicon-based precursor may further include Si3H8; during the formation of the heterojunction quantum well, within the target temperature range, Ge3H8 decomposes to obtain Ge2H6, and Si3H8 decomposes to obtain Si2H6.

[0051] In other words, the precursor can also include precursors with larger molecular weights, such as Ge3H8 and Si3H8, which can then serve as auxiliary precursors. Under low-temperature conditions, Ge3H8 decomposes to yield Ge2H6, and Si3H8 decomposes to yield Si2H6. (Reference) Figure 4The decomposition process is shown. The addition of these high-order precursors can modify the film layer interface, control dislocations, enhance interface bonding, inhibit interface stress defects, optimize atomic arrangement, and improve interface flatness, thereby improving the carrier mobility of the quantum well.

[0052] In a possible implementation, the silicon-based precursor further includes dichlorosilane, and in the process of forming the first barrier layer 104 and / or the second barrier layer 106, the dichlorosilane is introduced into the reaction chamber and reacts with the germanium-based precursor.

[0053] Specifically, when the barrier layer (for example, the first barrier layer 104 or the second barrier layer 106) is formed by CVD deposition, in order to improve the film layer quality of the barrier layer, dichlorosilane (SiH2Cl2) can be introduced into the chamber and reacts with the germanium-based precursor to generate Si 1-x Ge x The material layer, Si 1-x Ge x The interface quality of the material layer is better, and the interface roughness is lower.

[0054] In a possible implementation, when the heterojunction quantum well is a germanium heterojunction quantum well and the substrate 101 is a silicon substrate 101, before the first barrier layer 104 is formed, a precursor is used to generate a first buffer layer 1031 at a target temperature range, and the material of the first buffer layer 1031 is Si 1-x Ge x In the direction of the substrate 101 pointing to the first barrier layer 104, the Ge content in the first buffer layer 1031 gradually decreases.

[0055] Specifically, when the heterojunction quantum well is a Ge heterojunction quantum well, referring to Figure 2 As shown, before the first barrier layer 104 is formed on the substrate 101, a first buffer layer 1031 Si 1-x Ge x may be formed first. The first buffer layer 1031 Si 1-x Ge x The Ge content in the first buffer layer 1031 Si 1-x Ge x RG) can be considered as a silicon-germanium reverse graded layer (Si 1-x Ge x The more Si content and the less Ge content in the first barrier layer 104 of the first barrier layer 104 of the material, the smaller the dislocation between the first buffer layer 1031 and the first barrier layer 104, so that the quality of the first barrier layer 104 is less affected by the dislocation, and a higher-quality first barrier layer 104 can be obtained.

[0056] In a possible implementation, the first buffer layer 1031 is generated by decomposing a precursor and HCl in a target temperature range. That is, during the generation of the heterojunction quantum well, HCl can be added throughout the process, and HCl and the precursor are in a mixed state. HCl can increase the relaxation speed of the material, so that a thinner first buffer layer 1031 can be formed, and the film quality of the first buffer layer 1031 is improved.

[0057] For example, a thinner and better-quality first buffer layer 1031 can be obtained by reacting (Ge3H8+Si3H8), (Ge2H6+Si2H6), (Ge2H6+Si3H8), or (Ge3H8+Si2H6), and HCl. For example, the flow rate of HCl can be 0-300 sccm.

[0058] In a possible implementation, before the first buffer layer 1031 is formed, a germanium layer is generated on one side of the substrate 101 by decomposing a precursor in a target temperature range.

[0059] To improve the interface quality between the first buffer layer 1031 and the substrate 101, a Ge layer 102 can be formed therebetween. Since the Ge content is higher in the lower part of the first buffer layer 1031, the dislocation between the first buffer layer 1031 and the underlying Ge layer 102 is smaller, the film quality of the first buffer layer 1031 is improved, and the overall quality of the heterojunction quantum well is improved.

[0060] In actual applications, a 10-20 nm Ge layer 102 can be deposited with the assistance of a Ge2H6 precursor, and interface stress can be relieved by low-temperature annealing (350°C-400°C) to avoid defect propagation caused by stress. In addition, before the Ge layer 102 is formed, interface passivation treatment can be performed, that is, the substrate 101 is cleaned (for example, hydrofluoric acid treatment) before deposition to reduce surface oxides and ensure high-quality interface bonding.

[0061] In a possible implementation, when the heterojunction quantum well is a silicon heterojunction quantum well and the substrate 101 is a silicon substrate 101, a second buffer layer 1032 is generated by decomposing a precursor in a target temperature range before the first barrier layer 104 is formed, and the material of the second buffer layer 1032 is Si 1-x Ge x In the direction in which the substrate 101 points to the first barrier layer 104, the Ge content in the second buffer layer 1032 gradually increases.

[0062] Specifically, when the heterojunction quantum well is a Si heterojunction quantum well, the second buffer layer 1032 is generated by decomposing a precursor in a target temperature range before the first barrier layer 104 is formed, and the material of the second buffer layer 1032 is Si Figure 3As shown, before forming the first barrier layer 104, a second buffer layer 1032 can be formed on the substrate 101 using a precursor. 1-x Ge x In the second buffer layer 1032 of the material, the Ge content gradually increases from bottom to top. That is, the Ge content is higher in the upper part of the second buffer layer 1032, resulting in fewer dislocations between the first buffer layer 1031 and the first barrier layer 104 above it. At this time, the first buffer layer 1031 can be referred to as a silicon-germanium forward graded layer (Si). 1-x Ge x FG) improves the interface quality of the first buffer layer 1031.

[0063] In one possible implementation, the second buffer layer 1032 is generated by decomposing the precursor and HCl within a target temperature range. That is, HCl can be added throughout the formation process of the heterojunction quantum well. HCl and the precursor are in a mixed state, and HCl can increase the relaxation rate of the material, thereby forming a thinner second buffer layer 1032 and improving the film quality of the second buffer layer 1032.

[0064] As an example, a thinner and higher-quality second buffer layer 1032 can be obtained by reacting (Ge3H8+Si3H8), (Ge2H6+Si2H6), (Ge2H6+Si3H8), or (Ge3H8+Si2H6) with HCl. As an example, the HCl flow rate can be 0-300 sccm.

[0065] In one possible implementation, annealing is performed at a temperature range of 550°C to 950°C before forming the first barrier layer 104. That is, before forming the first barrier layer 104 on the substrate 101, the first buffer layer 1031, the second buffer layer 1032, and other films on the substrate 101 can be subjected to low-temperature annealing to further promote the rearrangement of surface atoms, improve the smoothness and structural stability of the interface, and further reduce the interface roughness.

[0066] In one possible implementation, HCl can be cyclically introduced to participate in the reaction during the formation of the heterojunction quantum well.

[0067] That is, in forming the first barrier layer 104, the quantum well layer 105 and the second barrier layer 106, of course, the HCl can also be introduced in a cyclic manner during the formation of the first buffer layer 1031 and the second buffer layer 1032, i.e. the HCl is introduced in small amounts multiple times, so that in the germanium heterojunction quantum well, the interface between the germanium layer and the first buffer layer 1031, the interface between the first buffer layer 1031 and the first barrier layer 104, the interface between the first barrier layer 104 and the quantum well layer 105, and the interface between the quantum well layer 105 and the second barrier layer 106 can be smoother, and the film quality and surface flatness generated by the high-order precursor can be improved.

[0068] Similarly, in the silicon heterojunction quantum well, the interface between the substrate 101 and the second buffer layer 1032, the interface between the second buffer layer 1032 and the first barrier layer 104, the interface between the first barrier layer 104 and the quantum well layer 105, and the interface between the quantum well layer 105 and the second barrier layer 106 can be smoother, and the film quality and surface flatness generated by the high-order precursor can be improved. As an example, the flow rate of HCl can be 0-300 sccm.

[0069] In summary, the influence of HCl on the dangling bonds makes the heterojunction interface roughness lower and the interface smoother.

[0070] In one possible implementation, a precursor is used to decompose in a target temperature range to form a cap layer 107 on the side of the second barrier layer 106 away from the quantum well layer 105, and the material of the cap layer 107 is silicon or germanium.

[0071] Specifically, a precursor is used to decompose in a target temperature range to form a cap layer 107 (CAP layer) above the second barrier layer 106, and the material of the cap layer 107 can be Si or Ge, so as to avoid the heterojunction quantum well being directly exposed to the environment and being oxidized and contaminated, and the quality of the heterojunction quantum well is improved.

[0072] As an example, refer to Figure 5 Fig. 1 shows a process schematic diagram of forming a Ge heterojunction quantum well provided by an embodiment of the present application, (a) shows a substrate 101, (b) shows a Ge layer 102, a first buffer layer 1031 and a first barrier layer 104 formed during deposition, and (c) shows a final Ge heterojunction quantum well. Figure 6 Fig. 2 shows a process schematic diagram of forming a Si heterojunction quantum well provided by an embodiment of the present application, (a) shows a substrate 101, (b) shows a second buffer layer 1032 and a first barrier layer 104 formed during deposition, and (c) shows a final Si heterojunction quantum well.

[0073] Based on the preparation method of the heterojunction quantum well above, the embodiment of the present application further provides a heterojunction quantum well, referring to Figure 2 and 3 As shown in the figure, the heterojunction quantum well includes a substrate 101, and a heterojunction quantum well located on one side of the substrate 101. The heterojunction quantum well includes a first barrier layer 104, a quantum well layer 105 and a second barrier layer 106 stacked in sequence, the first barrier layer 104 is located between the quantum well layer 105 and the substrate 101, the materials of the first barrier layer 104 and the second barrier layer 106 are both germanium silicon, when the heterojunction quantum well is a silicon heterojunction quantum well, the quantum well layer 105 is a silicon quantum well layer 105, and when the heterojunction quantum well is a germanium heterojunction quantum well, the quantum well layer 105 is a germanium quantum well layer 105.

[0074] Specifically, when the heterojunction quantum well is a Ge heterojunction quantum well, it can include a substrate 101, a Ge layer 102, a first buffer layer 1031, a first barrier layer 104, a quantum well layer 105, a second barrier layer 106 and a cap layer 107 stacked in sequence from bottom to top.

[0075] Specifically, when the heterojunction quantum well is a Si heterojunction quantum well, it can include a substrate 101, a second buffer layer 1032, a first barrier layer 104, a quantum well layer 105, a second barrier layer 106 and a cap layer 107 stacked in sequence from bottom to top.

[0076] The heterojunction quantum well provided by the embodiment of the present application can have a better interface quality of the heterojunction quantum well, each film layer can be more inclined to generate in a two-dimensional plane rather than a three-dimensional island, the surface roughness of the film layer can be reduced, and the high-quality preparation of the heterojunction quantum well can be realized.

[0077] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the difference from other embodiments. Especially, the device embodiment is described more simply because it is basically similar to the method embodiment, and the relevant part can be referred to the part of the method embodiment.

[0078] The above is only the preferred embodiment of the present application. Although the present application has been disclosed as above with the preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present application, or modify it into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, without departing from the content of the technical solution of the present application, still falls within the scope of protection of the technical solution of the present application.

Claims

1. A method for preparing a heterojunction quantum well, characterized in that, The application relates to a method for forming a heterojunction quantum well on a substrate. The method comprises the following steps: providing a substrate; forming a heterojunction quantum well on one side of the substrate by chemical vapor deposition; the heterojunction quantum well comprises a first barrier layer, a quantum well layer and a second barrier layer which are stacked in sequence, the first barrier layer is located between the quantum well layer and the substrate, the materials of the first barrier layer and the second barrier layer are both germanium silicon, when the heterojunction quantum well is a silicon heterojunction quantum well, the quantum well layer is a silicon quantum well layer, when the heterojunction quantum well is a germanium heterojunction quantum well, the quantum well layer is a germanium quantum well layer; 2. The method of claim 1, wherein, in the process of forming the heterojunction quantum well, a precursor is decomposed in a target temperature range, and a product obtained by decomposing the precursor is deposited on one side of the substrate to obtain the heterojunction quantum well; the precursor undergoes multi-stage reactions during decomposition, and the target temperature range is 300 DEG C to 550 DEG C.

3. The method of claim 2, wherein, The precursor comprises a silicon-based precursor and a germanium-based precursor, the germanium-based precursor comprises Ge2H6, and the silicon-based precursor comprises Si2H6; in the process of forming the heterojunction quantum well, in the target temperature range, the Ge2H6 is decomposed to obtain GeH4, the Si2H6 is decomposed to obtain SiH4, and the GeH4 and the SiH4 react to form the heterojunction quantum well.

4. The method according to claim 2 or 3, characterized in that, The germanium-based precursor further comprises Ge3H8, and the silicon-based precursor further comprises Si3H8; in the process of forming the heterojunction quantum well, in the target temperature range, the Ge3H8 is decomposed to obtain Ge2H6, and the Si3H8 is decomposed to obtain Si2H6.

5. The method of claim 1, wherein, In the case that the heterojunction quantum well is a germanium heterojunction quantum well and the substrate is a silicon substrate, a first buffer layer is formed by decomposing the precursor at the target temperature range before forming the first barrier layer, and the material of the first buffer layer is Si 1-x Ge x In the direction of the substrate pointing to the first barrier layer, the content of Ge in the first buffer layer gradually decreases.

6. The method of claim 5, wherein, The silicon-based precursor further comprises dichlorodihydrogen silicon, in the process of forming the first barrier layer and / or the second barrier layer, the dichlorodihydrogen silicon is introduced into a reaction chamber, and the dichlorodihydrogen silicon reacts with the germanium-based precursor.

7. The method of claim 5, wherein, The first buffer layer is generated by decomposing the precursor and HCl in the target temperature range.

8. The method of claim 1, wherein, In the case that the heterojunction quantum well is a silicon heterojunction quantum well and the substrate is a silicon substrate, a second buffer layer is formed by decomposing the precursor at the target temperature range before forming the first barrier layer, and the material of the second buffer layer is Si 1-x Ge x In the case that the substrate is gradually enriched with Ge in the second buffer layer in the direction of the first barrier layer.

9. The method of claim 8, wherein, Before forming the first buffer layer, a germanium layer located on one side of the substrate is generated by decomposing the precursor in the target temperature range.

10. The method according to any one of claims 5-9, characterized in that, The second buffer layer is generated by decomposing the precursor and HCl in the target temperature range.

11. The method of claim 1, wherein, Before forming the first barrier layer, an annealing treatment is performed in a temperature range of 550 DEG C to 950 DEG C.

12. The method of claim 1, wherein, In the process of forming the heterojunction quantum well, HCl is introduced into the reaction chamber in cycles to participate in the reaction.

13. A heterojunction quantum well, characterized in that, The precursor is decomposed in the target temperature range to form a cap layer on the side of the second barrier layer away from the quantum well layer, and the material of the cap layer is silicon or germanium. The application relates to a method for forming a heterojunction quantum well on a substrate. The method comprises the following steps: providing a substrate; forming a heterojunction quantum well on one side of the substrate; the heterojunction quantum well comprises a first barrier layer, a quantum well layer and a second barrier layer which are stacked in sequence, the first barrier layer is located between the quantum well layer and the substrate, the materials of the first barrier layer and the second barrier layer are both germanium silicon, when the heterojunction quantum well is a silicon heterojunction quantum well, the quantum well layer is a silicon quantum well layer, when the heterojunction quantum well is a germanium heterojunction quantum well, the quantum well layer is a germanium quantum well layer.

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