Hall sensor, preparation method thereof and detection system

Abstract

The invention discloses a Hall sensor, a preparation method thereof and a detection system, and belongs to the technical field of semiconductors. The Hall sensor comprises a plurality of sensing units, each sensing unit comprises a substrate, a semiconductor layer, a barrier layer, a sensitive metal layer, a first electrode, a second electrode, a third electrode and a fourth electrode, and the sensitive metal layer is used for detecting gas. The sensitive metal layer reacts with the detected gas to change the two-dimensional electron gas concentration at the heterostructure between the semiconductor layer and the barrier layer, so that the output voltage of the Hall sensor is influenced, and the gas detection is realized. The Hall sensor for gas detection provided by the embodiment of the invention has relatively high sensitivity and short response time, the sensitivity cannot be reduced along with the use time, the working time of a device is prolonged, the sensor can also utilize a four-phase current rotation method to eliminate offset voltage, the error influence of the device is avoided, and the measurement precision is improved.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor technology, and in particular, relates to a Hall sensor and a preparation method and a detection system thereof. Background Art

[0002] Currently, gas sensors can be divided into many categories according to different working principles, but most of them have problems such as low accuracy or resolution, or gradually reduced sensitivity over time and short service life.

[0003] Based on this, how to improve the accuracy and sensitivity of gas sensor detection, reduce the response time and increase the working time has become an urgent problem to be solved in this field. Summary of the invention

[0004] The present application provides a Hall sensor and a preparation method and a detection system thereof, aiming to improve the sensitivity of gas detection based on the Hall effect, reduce the response time, and increase the working time of the sensor.

[0005] In a first aspect, the present application provides a Hall sensor, which includes a plurality of sensing units, each of which includes: a substrate, a semiconductor layer, a barrier layer, a sensitive metal layer, a first electrode, a second electrode, a third electrode, and a fourth electrode. The semiconductor layer is arranged on the substrate, the barrier layer is arranged on the side of the semiconductor layer away from the substrate, and the sensitive metal layer is arranged on the side of the barrier layer away from the substrate, and the sensitive metal layer is used to detect gas. The first electrode and the second electrode are arranged on the side of the barrier layer away from the substrate, and the first electrode and the second electrode are arranged on opposite sides of the sensitive metal layer along a first direction parallel to the substrate. The third electrode and the fourth electrode are arranged on the side of the barrier layer away from the substrate, and the third electrode and the fourth electrode are arranged on opposite sides of the sensitive metal layer along a second direction parallel to the substrate. The second direction intersects with the first direction.

[0006] In some embodiments, the material of the sensitive metal layer includes at least one of platinum, palladium, a platinum alloy, a palladium alloy, or zinc oxide, and the sensitive metal layer is used to detect hydrogen.

[0007] In some embodiments, the Hall sensor further includes a first passivation layer and a second passivation layer, wherein the first passivation layer is disposed on a side of the barrier layer away from the substrate, and the first electrode, the second electrode, the third electrode, and the fourth electrode respectively penetrate the first passivation layer and are electrically connected to the barrier layer. The second passivation layer covers portions of the first electrode, the second electrode, the third electrode, and the fourth electrode, and the sensitive metal layer penetrates the second passivation layer and the first passivation layer and is connected to the barrier layer.

[0008] In some embodiments, the materials of the semiconductor layer and the barrier layer both include Group IIIA-VA elements.

[0009] In some embodiments, the material of the semiconductor layer includes at least one of gallium nitride, gallium arsenide, or indium gallium arsenide, and the material of the barrier layer includes at least one of indium gallium nitride, aluminum gallium nitride, indium phosphide, aluminum gallium arsenide, or indium aluminum arsenide.

[0010] In some embodiments, the Hall sensor further includes a buffer layer disposed between the substrate and the semiconductor layer.

[0011] In some embodiments, the Hall sensor further includes a cavity, and the cavity is arranged around the sensing unit along a direction parallel to the plane where the substrate is located, and the cavity is also arranged between the substrate and the semiconductor layer.

[0012] On the other hand, the present application also provides a method for preparing a Hall sensor, the Hall sensor comprising a plurality of sensing units, and the process of forming each sensing unit comprises the following steps S10 to S30:

[0013] Step S10: forming stacked semiconductor layers and barrier layers in sequence on a substrate.

[0014] Step S20: forming a first electrode, a second electrode, a third electrode and a fourth electrode. The first electrode and the second electrode are located on a side of the barrier layer away from the substrate, and along a first direction parallel to the substrate, the first electrode and the second electrode are located at opposite ends of the barrier layer. The third electrode and the fourth electrode are located on a side of the barrier layer away from the substrate, and along a second direction parallel to the substrate, the third electrode and the fourth electrode are located at opposite ends of the barrier layer. The second direction intersects with the first direction.

[0015] Step S30: forming a sensitive metal layer. The sensitive metal layer is located on the side of the barrier layer away from the substrate, between the first electrode and the second electrode, and between the third electrode and the fourth electrode, and is used to detect gas.

[0016] In some embodiments, after forming the sensitive metal layer, the process of forming each sensing unit further includes: etching the semiconductor layer and the substrate to form a cavity. In a direction parallel to the plane where the substrate is located, the cavity is located around the sensing unit and between the substrate and the semiconductor layer.

[0017] In a third aspect, the present application further provides a gas detection system, comprising the Hall sensor mentioned in any embodiment of the first aspect, and a magnet, wherein the magnet is used to provide a magnetic field for the Hall sensor.

[0018] The Hall sensor provided in the embodiment of the present application combines the Hall effect and the gas sensing principle. The semiconductor layer and the barrier layer form a heterojunction. An excitation source is provided through a pair of electrodes (a first electrode and a second electrode) to stimulate the generation of a two-dimensional electron gas in the heterojunction, and the Hall voltage is detected through another pair of electrodes (a third electrode and a fourth electrode).

[0019] Gas detection is performed using a sensitive metal layer. The sensitive metal layer reacts with the gas being detected, changing the two-dimensional electron gas concentration at the heterostructure between the semiconductor layer and the barrier layer, causing the Hall voltage output by the Hall sensor to change. The composition of the gas being detected is determined based on the type of sensitive metal and the change in Hall voltage.

[0020] Since the sensitive metal layer reacts more sensitively to the gas, and compared with the related technologies, the change in the two-dimensional electron gas concentration has a more obvious effect on the output voltage of the Hall sensor. Based on this, the Hall sensor for gas detection provided in the embodiment of the present application has high sensitivity and short response time. The sensitivity will not decrease with the use time, which increases the working time of the device. The sensor can also use the four-phase current rotation method to eliminate the offset voltage, avoid the influence of the device's own errors, and improve the measurement accuracy.

[0021] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] Figure 1 A top view of a Hall sensor provided in an embodiment of the present application;

[0024] Figure 2 for Figure 1 A cross-sectional view of the Hall sensor along the section line AA';

[0025] Figure 3 A flow chart of a method for preparing a Hall sensor provided in an embodiment of the present application;

[0026] Figures 4 to 12 A diagram of the steps for preparing a Hall sensor provided in an embodiment of the present application;

[0027] Fig.13 A schematic diagram of the structure of a gas detection system provided in an embodiment of the present application;

[0028] Fig.14 A schematic diagram of the structure of a gas detection system based on a permanent magnet provided in an embodiment of the present application;

[0029] Fig.15 A schematic structural diagram of a gas detection system based on an electromagnet core provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments provided by the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present application.

[0031] Unless the context requires otherwise, throughout the specification and claims, the term "comprising" is to be construed in an open, inclusive sense, ie, meaning "including, but not limited to."

[0032] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more.

[0033] When describing some embodiments, the term "connection" and its derivative expressions may be used. The term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For example, when describing some embodiments, the term "connection" may be used to indicate that two or more components are in direct physical or electrical contact with each other.

[0034] Additionally, the use of “based on” is meant to be open and inclusive, as a process, step, calculation, or other action “based on” one or more stated conditions or values ​​may, in practice, be based on additional conditions or values ​​beyond those stated.

[0035] It will be understood that when a layer or an element is referred to as being on another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present between the layer or element and the other layer or substrate.

[0036] Exemplary embodiments are described herein with reference to cross-sectional views that are idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are exaggerated for clarity. Therefore, variations in shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are conceivable. Therefore, the exemplary embodiments should not be interpreted as being limited to the shapes of the regions shown herein, but include deviations in shape due to, for example, manufacturing. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shape of regions of the device, and are not intended to limit the scope of the exemplary embodiments.

[0037] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0038] Gas sensors can be divided into many categories according to different working principles. For example, taking hydrogen sensors as an example, according to different working principles, hydrogen sensors can be divided into electrochemical, semiconductor, catalytic combustion and thermal conductivity. The electrochemical type has high sensitivity, good linearity, and stable zero drift, but its continuous use time is short, and the surface catalytic degree decreases with time, and the sensitivity decreases. The semiconductor type has a small structure, is easy to integrate, and has low cost, but its response time is long, power consumption is high, and linearity is poor. It can only be used for the detection of switching quantities. The catalytic combustion type has a short response time, high accuracy, and good durability, but the detection resolution is low and it is interfered by other combustible gases. The thermal conductivity type is simple in design and low in cost, but has poor sensitivity, and the signal processing of the back-end conditioning circuit is relatively complex. Other gas sensors also face similar problems.

[0039] In order to improve the accuracy and sensitivity of gas sensors, reduce the response time and increase the working time, the embodiment of the present application provides a Hall sensor, which performs gas detection based on the Hall effect, has the advantages of high sensitivity, short response time, high linearity, stable zero drift, etc., and has a very broad application prospect in gas detection.

[0040] like Figure 1-2 As shown, Figure 1 A top view of a Hall sensor provided in an embodiment of the present application, Figure 2 for Figure 1 The cross-sectional view of the Hall sensor along the section line AA' in FIG. 1 is a cross-sectional view of the Hall sensor 100, the Hall sensor 100 includes a plurality of sensing units 101, and one sensing unit 101 will be used as an example for the following description. It should be noted that: Figure 1 The figure is only for illustration, and does not limit the morphology of the sensitive metal layer 10 and the morphologies of the first electrode 11 , the second electrode 12 , the third electrode 13 , and the fourth electrode 14 .

[0041] like Figure 1-2 As shown, each sensing unit 101 of the Hall sensor 100 includes a substrate 1, a semiconductor layer 2, a barrier layer 3, a sensitive metal layer 10, a first electrode 11, a second electrode 12, a third electrode 13 and a fourth electrode 14. The semiconductor layer 2 is disposed on the substrate 1. Figure 1 The substrate 1 is not shown because it is covered by the semiconductor layer 2. The barrier layer 3 is arranged on the side of the semiconductor layer 2 away from the substrate 1, and the sensitive metal layer 10 is arranged on the side of the barrier layer 3 away from the substrate 1. The sensitive metal layer 10 is used to detect gas.

[0042] The first electrode 11 and the second electrode 12 are arranged on the side of the barrier layer 3 away from the substrate 1, and along the first direction X-axis parallel to the substrate 1, the first electrode 11 and the second electrode 12 are arranged on opposite sides of the sensitive metal layer 10. The third electrode 13 and the fourth electrode 14 are arranged on the side of the barrier layer 3 away from the substrate 1, and along the second direction Y-axis parallel to the substrate 1, the third electrode 13 and the fourth electrode 14 are arranged on opposite sides of the sensitive metal layer 10. The second direction Y-axis intersects with the first direction X-axis.

[0043] In the embodiment of the present application, gas detection is based on the Hall effect, as shown in a sensing unit 101 in the Hall sensor 100, the semiconductor layer 2 and the barrier layer 3 constitute a heterostructure, and a two-dimensional potential well is formed at the heterojunction interface. The positive charge attracts electrons to form a two-dimensional electron gas in the potential well. The two-dimensional electron gas is confined in the potential well and can only move two-dimensionally along a plane parallel to the heterojunction interface. The first electrode 11 and the second electrode 12 can be used as a group of input electrodes for connecting a working power supply to provide an excitation current to the sensing unit 101 to stimulate the generation of a two-dimensional electron gas in the heterojunction. Correspondingly, the third electrode 13 and the fourth electrode 14 are used as a group of output electrodes for outputting a detection voltage signal. Or vice versa, the third electrode 13 and the fourth electrode 14 are used as a group of input electrodes, and the first electrode 11 and the second electrode 12 are used as a group of output electrodes.

[0044] In the working state, taking the first electrode 11 and the second electrode 12 as a group of input electrodes as an example, when the detected gas in the environment reacts with the sensitive metal layer 10, the concentration of the two-dimensional electron gas changes, thereby affecting the output voltage signal at both ends of the output electrode. The detection of the detected gas component is achieved by analyzing the change of the output voltage signal.

[0045] Since the reaction of the sensitive metal layer 10 with the gas is relatively sensitive, and compared with the related technologies, the influence of the change of the two-dimensional electron gas concentration on the output voltage of the Hall sensor 100 is relatively obvious, based on this, the embodiment of the present application utilizes the reaction of the sensitive metal layer 10 with the detected gas and its influence on the two-dimensional electron gas concentration for detection, with high sensitivity and short response time.

[0046] In addition, in the embodiment of the present application, the Hall sensor 100 can also use the four-phase current rotation method to eliminate the accuracy influence caused by the offset voltage and temperature drift, thereby improving the measurement accuracy of the device. Exemplarily, during the operation of the device, the first phase is to use the first electrode 11 as the positive electrode of the excitation source, the second electrode 12 as the negative electrode of the excitation source, and the third electrode 13 and the fourth electrode 14 as the Hall voltage output terminal. The second phase is to use the third electrode 13 as the positive electrode of the excitation source, the fourth electrode 14 as the negative electrode of the excitation source, and the first electrode 11 and the second electrode 12 as the Hall voltage output terminal. The third phase is to use the second electrode 12 as the positive electrode of the excitation source, the first electrode 11 as the negative electrode of the excitation source, and the third electrode 13 and the fourth electrode 14 as the Hall voltage output terminal. The fourth phase is to use the fourth electrode 14 as the positive electrode of the excitation source, the third electrode 13 as the negative electrode of the excitation source, and the first electrode 11 and the second electrode 12 as the Hall voltage output terminal.

[0047] By controlling the supply of excitation sources for the four phases and the data collection of the output voltage signals through the clock signal, and averaging the output voltage signals of the four phases, the data information after eliminating the offset voltage and resisting the temperature drift can be obtained, thereby improving the detection accuracy.

[0048] In some embodiments, the material of the sensitive metal layer 10 includes at least one of platinum, palladium, platinum alloy, palladium alloy or zinc oxide, and the sensitive metal layer 10 is used to detect hydrogen. Since hydrogen is flammable, explosive, colorless and odorless, it needs to be monitored intensively in some environments but is difficult to detect. The above-mentioned metals such as platinum, palladium, platinum alloy, palladium alloy or zinc oxide can react with hydrogen to form hydrides without causing explosion risks, and can play a good role in hydrogen detection technology. In the embodiment of the present application, the power loss during the operation of the Hall sensor 100 causes the device temperature to rise. The rising temperature can be used to catalyze the reaction between the sensitive metal layer 10 and hydrogen, and detection can be performed without adding a heater, making the device structure simpler and the cost lower.

[0049] In addition, in different sensing units 101 of the Hall sensor 100, the material of the sensitive metal layer 10 can also be set to other materials, and the characteristics of different types of sensitive metals can be used to detect other gases.

[0050] In some embodiments, the materials of the semiconductor layer 2 and the barrier layer 3 include Group IIIA-VA elements, such as aluminum, gallium, nitrogen, arsenic, and the like.

[0051] In some embodiments, the material of the semiconductor layer 2 includes at least one of gallium nitride, gallium arsenide or indium gallium arsenide, and the material of the barrier layer 3 includes at least one of indium gallium nitride, aluminum gallium nitride, indium phosphide, aluminum gallium arsenide or indium aluminum arsenide.

[0052] The above materials have high electron mobility and good semiconductor properties, so that the sensing unit 101 has high sensitivity, which is beneficial to improving the detection range of the Hall sensor 100 .

[0053] In some embodiments, Figure 2 As shown, in order to avoid lattice mismatch and dislocation, the Hall sensor 100 further includes a buffer layer 4 disposed between the substrate 1 and the semiconductor layer 2. The buffer layer 4 is used to reduce lattice mismatch and dislocation density.

[0054] In some embodiments, Figure 1 and Figure 2 As shown, the Hall sensor 100 further includes a cavity K1 . The cavity K1 is arranged around the sensing unit 101 along a direction parallel to the plane where the substrate 1 is located, and the cavity K1 is also arranged between the substrate 1 and the semiconductor layer 2 .

[0055] The setting of the cavity K1 can reduce the conduction loss of heat in the solid, so that the device temperature rise caused by power loss during the operation of the Hall sensor 100 is retained as much as possible in the "middle part" surrounded by the cavity K1, to avoid the temperature rising and then dropping rapidly. The "middle part" here includes the semiconductor layer 2, the barrier layer 3, the sensitive metal layer 10, the first electrode 11 and the second electrode 12, the third electrode 13 and the fourth electrode 14, which play a major role in the gas detection process. By setting the cavity K1, the result of the temperature rise can be effectively retained near the sensitive metal layer 10, which is used to catalyze the reaction between the sensitive metal layer 10 and the detected gas, which is beneficial to the self-polarization effect of the heterostructure, thereby improving the measurement sensitivity and measurement accuracy.

[0056] On the other hand, the present application also provides a method for preparing a Hall sensor, wherein the Hall sensor 100 includes a plurality of sensing units 101, such as Figure 3 As shown, Figure 3 A flow chart of a method for preparing a Hall sensor provided in an embodiment of the present application, Figures 4 to 12 The steps of preparing a Hall sensor provided in the embodiment of the present application are shown in FIG. Taking the formation of a sensor unit as an example, the preparation method includes the following steps S10 to S30:

[0057] Step S10: Figure 4-5 As shown, a semiconductor layer 2 and a barrier layer 3 are stacked in sequence on a substrate 1 .

[0058] like Figure 4As shown, a stacked structure of a substrate 1, a semiconductor layer 2 and a barrier thin layer 30 is formed. The substrate 1 is usually a silicon substrate or a sapphire substrate, and the semiconductor layer 2 usually includes IIIA-VA elements, such as gallium nitride, gallium arsenide or indium gallium arsenide. In order to avoid lattice mismatch and dislocation, a buffer layer 4 is usually provided between the substrate 1 and the semiconductor layer 2 to reduce the lattice mismatch and dislocation density, thereby improving the performance and reliability of the device. For example, the material of the buffer layer 4 includes aluminum nitride, the material of the semiconductor layer 2 includes gallium nitride, and the material of the barrier layer 3 includes aluminum gallium nitride.

[0059] Afterwards, if Figure 5 As shown, the barrier thin layer 30 is patterned, and the barrier thin layer 30 in the redundant area is etched away, and the barrier layer 3 is retained. Figure 1 or Figure 2 The projection area of ​​the barrier layer 3 on the substrate 1 is shown, and the barrier thin layer 30 in the area is retained by patterning, and the excess barrier thin layer 30 around is removed by etching. Exemplarily, the barrier thin layer 30 can be removed by etching with an inductively coupled plasma etching process.

[0060] To form good electrical contact, Figure 6 As shown, after the patterning process is completed, an ohmic contact layer 5 is also formed on the barrier layer 3. Exemplarily, the metal patterning of the ohmic contact is formed by metal evaporation and rapid annealing, and the metal types include but are not limited to gold, aluminum, platinum, molybdenum, etc.

[0061] Step S20: Figure 7-Figure 8 As shown, a first electrode 11, a second electrode 12, a third electrode 13 and a fourth electrode 14 are formed. The first electrode 11 and the second electrode 12 are located on the side of the barrier layer 3 away from the substrate 1, and along the first direction X-axis parallel to the substrate 1, the first electrode 11 and the second electrode 12 are located at opposite ends of the barrier layer 3. The third electrode 13 and the fourth electrode 14 are located on the side of the barrier layer 3 away from the substrate 1, and along the second direction Y-axis parallel to the substrate 1, the third electrode 13 and the fourth electrode 14 are located at opposite ends of the barrier layer 3. The second direction Y-axis intersects with the first direction X-axis.

[0062] For example, Figure 7 As shown, after the ohmic contact layer 5 is formed, the first passivation layer 6 is first formed and etched to expose a portion of the ohmic contact layer 5 for subsequent formation of the first electrode 11 , the second electrode 12 , the third electrode 13 and the fourth electrode 14 .

[0063] Afterwards, if Figure 8As shown, a metal material is deposited on the exposed ohmic contact layer 5 to form a good electrical connection with the ohmic contact layer 5, and after removing the redundant portion by etching, a first electrode 11, a second electrode 12, a third electrode 13 and a fourth electrode 14 are finally formed.

[0064] Then, if Fig. 9 As shown, the second passivation layer 7 is formed and etched, so that the second passivation layer 7 exposes part of the barrier layer 3 for the subsequent formation of the sensitive metal layer 10. In addition, the second passivation layer 7 exposes part of the first electrode 11, part of the second electrode 12, part of the third electrode 13 and part of the fourth electrode 14 for connection with an external circuit.

[0065] The first passivation layer 6 and the second passivation layer 7 are both used for protection and isolation, and the materials of both can be silicon oxide, aluminum oxide or silicon nitride.

[0066] Step S30: Fig.10 As shown, a sensitive metal layer 10 is formed on the portion of the barrier layer 3 exposed by the second passivation layer. The sensitive metal layer 10 is located on the side of the barrier layer 3 away from the substrate 1, and is located between the first electrode 11 and the second electrode 12, and between the third electrode 13 and the fourth electrode 14. The sensitive metal layer 10 is used to detect gas.

[0067] When the Hall sensor 100 is used to detect hydrogen, the material of the sensitive metal layer 10 may include at least one of platinum, palladium, a platinum alloy, a palladium alloy, or zinc oxide.

[0068] In some embodiments, after forming the sensitive metal layer 10, as Figure 11-12 As shown, the process of forming each sensor unit 101 further includes: etching the semiconductor layer 2 and the substrate 1 to form a cavity K1. The cavity K1 is located around the sensor unit 101 and between the substrate 1 and the semiconductor layer 2 in a direction parallel to the plane of the substrate 1.

[0069] For example, Fig.11 As shown, the second passivation layer 7, the first passivation layer 6, the semiconductor layer 2 and the buffer layer 4 are first etched to form a via hole V1 exposing the substrate 1. Fig.12 As shown, deep silicon etching is performed using the via V1 to continue removing part of the substrate 1, and finally forming a cavity K1, so that the "middle part" of the sensor unit 101 is formed into a structure similar to a suspended island, that is, the "middle part" is surrounded by the cavity K1, and the "middle part" is integrally connected to the sensor unit 101 through a portion of the semiconductor layer 2 and other film layers that have not been etched. The "middle part" includes the semiconductor layer 2, the barrier layer 3, the sensitive metal layer 10, the first electrode 11, the second electrode 12, the third electrode 13 and the fourth electrode 14, and plays a major role in the gas detection process.

[0070] The preparation process of the above preparation method is relatively simple, and the prepared Hall sensor 100 has high sensitivity and short response time when performing gas detection, and can also eliminate the accuracy influence caused by offset voltage and temperature drift, thereby improving the measurement accuracy of the device. In addition, the etching to form the cavity K1 in the above preparation method is also beneficial to reduce the conduction loss of heat in the solid, so that the device temperature rise caused by power loss during the operation of the Hall sensor 100 is retained as much as possible in the "middle part" to catalyze the reaction between the sensitive metal layer 10 and the detected gas, which is beneficial to the self-polarization effect of the heterogeneous structure, thereby improving the measurement sensitivity and measurement accuracy, and detection can be performed without a muscle-enhanced heater, further simplifying the preparation process.

[0071] In a third aspect, the present application also provides a gas detection system, such as Fig.13 As shown, Fig.13 A structural schematic diagram of a gas detection system provided in an embodiment of the present application, the gas detection system 200 includes the Hall sensor 100 mentioned in any embodiment of the first aspect above and a magnet 201, the magnet 201 is used to provide a magnetic field for the Hall sensor 100, the magnet 201 can be a permanent magnet or an electromagnet core.

[0072] For example, Figure 14-15 As shown, Fig.14 A schematic diagram of the structure of a gas detection system based on a permanent magnet provided in an embodiment of the present application is shown in FIG. Fig.15 A schematic structural diagram of a gas detection system based on an electromagnet core provided in an embodiment of the present application.

[0073] Since the magnitude of the output voltage of the Hall sensor 100 is positively correlated with the magnitude of the magnetic field, the magnitude of the Hall voltage output by the Hall sensor 10 can be linearly adjusted by changing the magnitude of the magnetic field, thereby adjusting the signal amplification factor before the back-end circuit processing, thereby increasing the measurement range and making the detection range wider.

[0074] For example, Fig.14 As shown, permanent magnets with different magnetic magnitudes are selected to change the magnetic field magnitude, or as Fig.15 As shown, the magnitude of the exciting current of the electromagnet core is adjusted to change the magnitude of the magnetic field.

[0075] The gas detection system provided in the embodiment of the present application is based on the Hall effect, and uses the reaction between the sensitive metal layer 10 and the detected gas and its influence on the concentration of the two-dimensional electron gas to detect the gas. It has high sensitivity and short response time, and can also eliminate the accuracy influence caused by the offset voltage and temperature drift, thereby improving the measurement accuracy of the device. In addition, the output voltage can be linearly adjusted by changing the size of the magnetic field, thereby increasing the measurement range and making the detection range wider.

[0076] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that a person skilled in the art can think of within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A Hall sensor, characterized in that: including a sensing unit; The sensing unit comprises: substrate; A semiconductor layer is disposed on the substrate; A barrier layer, disposed on a side of the semiconductor layer away from the substrate; A sensitive metal layer, disposed on a side of the barrier layer away from the substrate, the sensitive metal layer being used for detecting gas; A first electrode and a second electrode are arranged on a side of the barrier layer away from the substrate; along a first direction parallel to the substrate, the first electrode and the second electrode are arranged on opposite sides of the sensitive metal layer; The third electrode and the fourth electrode are arranged on a side of the barrier layer away from the substrate; along a second direction parallel to the substrate, the third electrode and the fourth electrode are arranged on opposite sides of the sensitive metal layer, and the second direction intersects with the first direction.

2. The Hall sensor according to claim 1, characterized in that: The material of the sensitive metal layer includes at least one of platinum, palladium, a platinum alloy, a palladium alloy or zinc oxide, and the sensitive metal layer is used to detect hydrogen.

3. The Hall sensor according to claim 1, characterized in that: The Hall sensor further includes a first passivation layer and a second passivation layer, the first passivation layer is arranged on a side of the barrier layer away from the substrate, and the first electrode, the second electrode, the third electrode and the fourth electrode respectively penetrate the first passivation layer and are electrically connected to the barrier layer; The second passivation layer covers parts of the first electrode, the second electrode, the third electrode, and the fourth electrode; The sensitive metal layer penetrates the second passivation layer and the first passivation layer and is connected to the barrier layer.

4. The Hall sensor according to claim 1, characterized in that: The materials of the semiconductor layer and the barrier layer both include group IIIA-VA elements.

5. The Hall sensor according to claim 1, characterized in that: The material of the semiconductor layer includes at least one of gallium nitride, gallium arsenide or indium gallium arsenide, and the material of the barrier layer includes at least one of indium gallium nitride, aluminum gallium nitride, indium phosphide, aluminum gallium arsenide or indium aluminum arsenide.

6. The Hall sensor according to claim 1, characterized in that: The Hall sensor further includes a buffer layer disposed between the substrate and the semiconductor layer.

7. The Hall sensor according to claim 1, characterized in that: The Hall sensor further comprises a cavity, which is arranged around the sensing unit in a direction parallel to the plane where the substrate is located, and the cavity is also arranged between the substrate and the semiconductor layer.

8. A method for preparing a Hall sensor, characterized in that: The Hall sensor includes a plurality of sensing units; Forming the sensing unit includes: sequentially forming a stacked semiconductor layer and a barrier layer on a substrate; A first electrode, a second electrode, a third electrode and a fourth electrode are formed, wherein the first electrode and the second electrode are located at a side of the barrier layer away from the substrate; along a first direction parallel to the substrate, the first electrode and the second electrode are located at two opposite ends of the barrier layer; the third electrode and the fourth electrode are located at a side of the barrier layer away from the substrate; along a second direction parallel to the substrate, the third electrode and the fourth electrode are located at two opposite ends of the barrier layer, and the second direction intersects with the first direction; A sensitive metal layer is formed, the sensitive metal layer is located on a side of the barrier layer away from the substrate; the sensitive metal layer is located between the first electrode and the second electrode, and between the third electrode and the fourth electrode, and the sensitive metal layer is used to detect gas.

9. The preparation method according to claim 8, characterized in that: After forming the sensitive metal layer, the method further includes: The semiconductor layer and the substrate are etched to form a cavity; along a direction parallel to the plane where the substrate is located, the cavity is located around the sensing unit and between the substrate and the semiconductor layer.

10. A gas detection system, characterized in that: include: The Hall sensor according to any one of claims 1 to 7; A magnet is used to provide a magnetic field for the Hall sensor.

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