A photoexcited semiconductor gas sensor

Abstract

The present application relates to the technical field of semiconductor gas sensors, and solves the problem of packaging and integrating the light source and sensitive chip of a light-excited semiconductor gas sensor in the prior art. The present application discloses a light-excited semiconductor gas sensor, comprising a base, on which an LED light source is arranged, and the pins of the LED light source are electrically connected to the LED pins, wherein the LED pins all pass through the base; and a gas-sensitive element, wherein the gas-sensitive element is arranged above the LED light source, and the electrodes of the gas-sensitive element are electrically connected to the pins of the gas-sensitive element. The present application realizes the integration and packaging of the light source and the sensor chip, and the packaging method is simple and easy to implement. The volume after packaging is small, and it is convenient to inspect and repair the internal LED light source and gas-sensitive element, which is conducive to the industrialization of light-excited semiconductor gas sensors.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor gas sensors, and in particular to a light-excited semiconductor gas sensor. Background Art

[0002] In recent years, gas sensors have shown good application prospects in air quality monitoring, food safety management, home smart control, medical health diagnosis, etc. The research and development of new gas sensors has become increasingly urgent and has received widespread attention. Semiconductor oxide (MOS) gas sensors are the frontier direction and research hotspot in the field of gas sensor research due to their advantages such as all-solid-state, simple structure, low cost, small size, and adjustable performance. At present, commercial MOS gas sensors are still mainly thermally excited, and their thermal excitation temperature can reach above 300°C. During the service of the sensor, while the gas-sensitive layer maintains excellent gas-sensitive performance, the long-term heating process above 300°C will cause the grain growth and grain boundary migration of the gas-sensitive layer, resulting in the drift of the sensor zero point, causing false alarms of gas in actual work. In addition, thermally excited semiconductor gas sensors working at high temperatures above 300°C also face the problems of high energy consumption and high temperature safety.

[0003] In order to solve the problems faced by the above commercial thermally excited MOS sensors, people have proposed a solution to use light as energy excitation to supply semiconductor gas-sensitive materials. The Chinese patent with publication number CN111624236A discloses a thin-film type light-excited semiconductor thin-film gas sensor and its preparation method, the Chinese patent with publication number CN116087277A provides a light pulse test method for thin-film type light-excited semiconductor sensors, and the publication number CN117191890A discloses a visible light-excited gas sensor, which in principle involves using photons to improve the excitation efficiency of LSPR in precious metals, thereby improving the detection sensitivity. From the existing patents disclosed for light-excited semiconductor sensors, the research and development of this technology focuses on the regulation of light-excited sensing performance and the improvement of test solutions. It needs to be further promoted in terms of terminal applications, and has not involved the packaging and integration of light sources and sensitive chips. Utility Model Content

[0004] The purpose of the present application is to overcome the problem of packaging and integrating the light source and the sensitive chip of a light-excited semiconductor gas sensor in the prior art, and to provide a light-excited semiconductor gas sensor.

[0005] Specifically, the light-excited semiconductor gas sensor includes: a base, on which an LED light source is arranged, and the pins of the LED light source are electrically connected to the LED pins, wherein the LED pins all pass through the base; a gas sensitive element, wherein the gas sensitive element is arranged above the LED light source, and the electrodes of the gas sensitive element are electrically connected to the gas sensitive element pins, wherein the gas sensitive element pins all pass through the base; and a tube cap, wherein the tube cap is detachably arranged on the base, the LED light source and the gas sensitive element are both placed in the tube cap, and a ventilation channel is reserved in the tube cap and / or the base.

[0006] In some possible implementations, the tube cap includes a cap head and a flat cover, wherein a plurality of ventilation holes are provided at the upper end of the cap head, and a flat cover is fixed to the lower end of the cap head, wherein the flat cover is used to connect with the base, and other external substances enter the space between the tube cap and the base through the ventilation holes and contact the gas sensitive element.

[0007] In some possible implementations, the base includes a support platform and a boss, the cap head is sleeved on the outer wall of the boss and the cap head and the boss are fixed by the friction force between the cap head and the boss, the LED light source is arranged on the boss, and when assembling the base and the pipe cap, it is only necessary to align the pipe cap with the boss of the base, and press the pipe cap to sleeve on the outer wall of the boss so that the flat cover fits with the support platform, and the cap head and the boss can be fixed by the friction force between the cap head and the boss.

[0008] In some possible implementations, the tube cap and the base are detachably fixed together by solder or hot melt adhesive. At room temperature, the tube cap and the base are firmly connected. When the tube cap and the base need to be separated, the tube cap and the base can be separated by simply heating the solder or hot melt adhesive connection again.

[0009] In some possible implementations, the gas-sensitive element includes a ceramic sheet, an interdigital electrode and a gas-sensitive layer, wherein the ceramic sheet is disposed on one side of the interdigital electrode, and the gas-sensitive layer is disposed on the other side of the interdigital electrode, and the gas-sensitive layer faces the LED light source.

[0010] In some possible implementations, the ceramic sheet is an alumina-based ceramic material, and the interdigitated electrodes are formed of a gold or platinum film layer.

[0011] In some possible implementations, the length of the ceramic sheet is 0.5mm-1.0mm, the width of the ceramic sheet is 0.5mm-1.0mm, and the thickness of the ceramic sheet is 0.2mm-0.3mm, which can reduce the volume of the ceramic sheet as much as possible, thereby reducing the production cost and reducing the size of the integrated light-excited semiconductor gas sensor.

[0012] In some possible implementations, the sensitive layer is tin oxide, zinc oxide, tungsten oxide, indium oxide or titanium oxide based on semiconductor gas-sensitive ceramic.

[0013] In some possible implementations, the top of the gas sensor pin is higher than the top of the LED pin.

[0014] In some possible implementations, the tops of the LED pins and the gas sensor pins are both provided with nail heads, the tops of the gas sensor pins are higher than the tops of the LED pins, and the length difference between the LED pins and the gas sensor pins ensures that enough light is irradiated onto the gas sensitive layer. The pins are provided with protruding nail heads to facilitate the welding of the leads.

[0015] In some possible implementations, the LED pins and the gas sensor pins are both fixedly connected to the base, so that the LED pins and the gas sensor pins can be fixed after assembly.

[0016] The present application has the following beneficial effects: the LED light source and the gas sensor can be integrated and assembled in the space between the base and the tube cap, the external air can enter the space from the ventilation channel and contact the gas sensor, and the LED light source provided below the gas sensor provides light to stimulate the gas sensor to work, and the power supply and signal transmission are started through the LED pins and the gas sensor pins. After the LED light source and the gas sensor are connected to the corresponding LED pins and the gas sensor pins through the leads, the tube cap and the base are fixed to realize the packaging of the sensor. The packaging method is simple and easy to realize. The volume after packaging is small, and it is convenient to inspect and repair the internal LED light source and gas sensor. In addition, the LED light source and the gas sensor are packaged in the same sensor probe, taking into account the practical application of the light-excited semiconductor sensor. Compared with the prior art, the present application provides a new solution for the practical application of the light-excited semiconductor sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application.

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 is a schematic structural diagram of a light-excited semiconductor gas sensor according to an embodiment of the present application;

[0020] Figure 2 is a schematic diagram of the structure of a tube cap in a light-excited semiconductor gas sensor according to an embodiment of the present application;

[0021] Figure 3 It is a schematic diagram of the structure of the LED light source and the gas sensing element in the light-excited semiconductor gas sensor of the embodiment of the present application;

[0022] Figure 4 It is a schematic diagram of the structure of the gas sensing element and the gas sensing element pins in the light-excited semiconductor gas sensor of the embodiment of the present application;

[0023] Figure 5 It is a schematic diagram of the structure of the LED light source and LED pins in the light-excited semiconductor gas sensor of the embodiment of the present application;

[0024] Figure 6 The structure of the interdigital electrode in the light-excited semiconductor gas sensor of the embodiment of the present application is shown in FIG. Figure 1 ;

[0025] Figure 7 The structure of the interdigital electrode in the light-excited semiconductor gas sensor of the embodiment of the present application is shown in FIG. Figure 2 ;

[0026] Figure 8 It is a schematic diagram of the structure of the gas sensitive element in the light-excited semiconductor gas sensor of the embodiment of the present application.

[0027] Reference numerals:

[0028] 1. Base; 11. Support platform; 12. Boss; 2. LED light source; 3. LED pin; 4. Gas sensor; 41. Ceramic sheet; 42. Interdigital electrode; 43. Gas sensing layer; 5. Gas sensor pin; 6. Cap; 61. Ventilation channel; 62. Cap head; 63. Flat cover; 64. Ventilation hole; 7. Nail head; 8. Lead wire. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application; obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application without making creative work are within the scope of protection of the present application.

[0030] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0031] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "set / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0032] See also Figure 1-Figure 3 A preferred embodiment of the present application is a light-excited semiconductor gas sensor, comprising a base 1, a gas sensitive element 4 and a cap 6, wherein an LED light source 2 is fixed on the base 1, and the gas sensitive element 4 is arranged above the LED light source 2.

[0033] like Figure 2 As shown, the tube cap 6 includes a cap head 62 and a flat cover 63. A plurality of vent holes 64 are provided at the upper end of the cap head 62. The flat cover 63 is fixed to the lower end of the cap head 62. The cap head 62 and the flat cover 63 are integrally formed of nickel alloy. The cap head 62 is a hollow structure. The vent holes 64 are evenly distributed above the cap head 62. The flat cover 63 contacts the base 1 to achieve packaging.

[0034] like Figure 3 As shown, the base 1 includes a support platform 11 and a boss 12, the cap head 62 is sleeved on the outer wall of the boss 12 and the cap head 62 and the boss 12 are fixed by the friction between the cap head 62 and the boss 12, the LED light source 2 is arranged on the boss 12, and when packaging, the tube cap 6 can be pressed to make the flat cover 63 contact with the support platform 11, and the tube cap 6 and the base 1 are fixed by the friction between the boss 12 and the inner wall of the tube cap 6.

[0035] like Figure 6-Figure 8As shown, the gas sensor 4 includes a ceramic sheet 41, an interdigital electrode 42 and a gas sensitive layer 43. The ceramic sheet 41 and the gas sensitive layer 43 are respectively arranged on the two sides of the interdigital electrode 42. The gas sensitive layer 43 faces the LED light source 2 so that the light emitted by the LED light source 2 can be irradiated on the gas sensitive layer 43, thereby stimulating the gas sensitive element 4 to work. The ceramic sheet 41 is an alumina-based ceramic material with an alumina content of 75%-95%. The length of the ceramic sheet 41 is 0.5mm-1.0mm, the width of the ceramic sheet 41 is 0.5mm-1.0mm, and the thickness of the ceramic sheet 41 is 0.2mm-0.3mm. The interdigital electrode 42 is composed of a gold or platinum film layer, which can be prepared by screen printing technology or magnetron sputtering technology. Figure 6 and Figure 7 As shown, the interdigitated electrodes 42 may be a single electrode or multiple electrodes. Figure 8 As shown, the sensitive layer is tin oxide, zinc oxide, tungsten oxide, indium oxide or titanium oxide based on semiconductor gas-sensitive ceramics. The gas-sensitive layer 43 is prepared by screen printing, magnetron sputtering and other technologies. For light-excited semiconductor combustible gas sensors, the main component of the gas-sensitive material can be tin oxide. By adding sensitizers and other components for adjusting resistance values, a high-signal combustible gas response is achieved. When the gas-sensitive element 4 is welded, the gas-sensitive layer 43 faces the LED light source 2, as shown in FIG. Figure 4 shown.

[0036] like Figure 3 As shown, a reflector for focusing light is provided below the LED light source 2, so that the light emitted by the LED light source 2 can be irradiated more on the gas-sensitive layer 43 of the gas-sensitive element 4, thereby improving the utilization rate of light. The LED light source 2 generally emits peripheral ultraviolet light with a wavelength of 365nm.

[0037] like Figure 3 As shown, the tops of the LED pins 3 and the gas sensor pins 5 are both provided with nail heads 7, and the tops of the gas sensor pins 5 are higher than the tops of the LED pins 3. In order to prevent the LED pins 3 and the gas sensor pins 5 from shaking after assembly, the LED pins 3 and the gas sensor pins 5 are both fixedly connected to the base 1.

[0038] In another possible embodiment, the tube cap 6 and the base 1 are detachably fixed together by solder or hot melt adhesive. At room temperature, the tube cap 6 and the base 1 are firmly connected. When the tube cap 6 and the base 1 need to be separated, the tube cap 6 and the base 1 can be separated by simply heating the solder or hot melt adhesive connection again.

[0039] The light-excited semiconductor gas sensor in this embodiment can be prepared by the following process:

[0040] The preparation and packaging of the gas sensor 4 include: the preparation of the interdigital electrode 42 and the gas-sensitive layer 43. First, the gold paste is printed on the ceramic substrate through the designed electrode pattern by screen printing technology, and then sintered at 850°C to form the gold interdigital electrode 42. Then, the prepared gas-sensitive paste is printed on the ceramic substrate by screen printing, and sintered to form the gas-sensitive layer 43. Finally, the platinum wire is welded to the pad by a welding machine. Through the above three steps, the preparation of the gas sensor 4 can be completed, and then the gas sensor 4 is packaged. First, the LED light source 2 is welded on the LED pin 3 through the lead 8, wherein, as Figure 5 As shown, since the LED light source 2 has two pins, two LED pins 3 are required, and then the gas sensor 4 is welded to the gas sensor pin 5 through the lead 8. Similarly, Figure 4 As shown, there are also two gas sensor pins 5. Since the top of the gas sensor pin 5 is higher than the top of the LED pin 3, the lead wire 8 leading out of the gas sensor 4 is straightened and respectively welded to the cap heads 62 at the top of the two gas sensor pins 5 during welding, so that the gas sensor 4 is located above the LED light source 2. It should be noted that the gas sensitive layer 43 needs to be facing the LED light source 2. Finally, the cap 6 is pressed onto the base 1, thereby realizing the preparation of the light-excited semiconductor gas sensor.

[0041] In the above embodiment, the LED light source 2 and the gas sensor 4 can be integrated and assembled in the space between the base 1 and the tube cap 6, and the external air can enter the space from the ventilation channel 61 and contact the gas sensor 4, and the LED light source 2 provided below the gas sensor 4 is used to provide light to stimulate the gas sensor 4 to work, and the power supply and signal transmission are started through the LED pin 3 and the gas sensor pin 5. After the LED light source 2 and the gas sensor 4 are connected with the corresponding LED pin 3 and the gas sensor pin 5 through the lead 8, the tube cap 6 and the base 1 are fixed to realize the packaging of the sensor. The packaging method is simple and easy to implement. In addition, the LED light source 2 and the gas sensor 4 are packaged in the same sensor probe, taking into account the practical application of the light-excited semiconductor sensor. Compared with the prior art, the present application provides a new solution for the light-excited semiconductor sensor to move towards practical application.

[0042] The working principle of the optically excited semiconductor gas sensor of this embodiment is as follows:

[0043] At room temperature, the gas-sensitive layer 43 absorbs oxygen in the air. Due to the high oxidizing property of oxygen, it will take away electrons from the gas-sensitive layer 43 to form oxygen O2 -ions, when the gas-sensitive element 4 is powered on, the light emitted by the LED light source 2 will irradiate the gas-sensitive layer 43 and be absorbed (if the gas-sensitive layer 43 is designed according to the combustible gas, it is an ultraviolet LED light source 2). After the electrons in the gas-sensitive layer 43 absorb the photon energy, they will be excited from the valence band to the conduction band to form hole-electron pairs, and the holes will react with O2 - The electrons in the ions are neutralized, causing the previously adsorbed O2 to desorb, and the electrons (called photoelectrons) will form new O2 with the O2 adsorbed by the gas-sensitive layer 43. - At this time, the gas-sensitive layer 43 is filled with new O2 - The effect is in a high resistance state. At this time, if the gas sensor 4 contacts the target gas, it will react with the O2 - reaction, capturing photons causing O2 - The photoelectrons in the gas-sensitive layer 43 cause the resistance value of the gas-sensitive layer 43 to decrease, thereby realizing the detection of the target gas. When the target gas disappears from the environment, due to the continuous LED illumination, new light-excited O2 - , maintaining a stable high resistance state. Because the gas-sensitive layer 43 receives lower energy than the state of thermal excitation under the action of LED light, it can maintain a more stable state, which can effectively solve the stability and high power consumption problems faced by thermally excited semiconductor gas sensors.

[0044] The above are only preferred specific implementations of the present application; however, the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solution and its improved ideas of the present application within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A light-excited semiconductor gas sensor, characterized in that: include: A base, wherein an LED light source is disposed on the base, wherein the pins of the LED light source are electrically connected to the LED pins, wherein the LED pins all pass through the base; A gas sensor, wherein the gas sensor is disposed above the LED light source, wherein the electrode of the gas sensor is electrically connected to the gas sensor pin, wherein the gas sensor pins all pass through the base; The tube cap is detachably arranged on the base, the LED light source and the gas sensor are both placed in the tube cap, and a ventilation channel is reserved in the tube cap and / or the base.

2. The optically excited semiconductor gas sensor according to claim 1, characterized in that: The pipe cap comprises a cap head and a flat cover, a plurality of vent holes are provided at the upper end of the cap head, and a flat cover is fixed at the lower end of the cap head.

3. The optically excited semiconductor gas sensor according to claim 2, characterized in that: The base comprises a supporting platform and a boss, the cap head is sleeved on the outer wall of the boss and the cap head and the boss are fixed by the friction force between the cap head and the boss, and the LED light source is arranged on the boss.

4. The optically excited semiconductor gas sensor according to claim 1, characterized in that: The tube cap and the base are detachably fixed together by soldering tin or hot melt adhesive.

5. The optically excited semiconductor gas sensor according to claim 1, characterized in that: The gas-sensitive element comprises a ceramic sheet, an interdigital electrode and a gas-sensitive layer. The ceramic sheet is arranged on one side of the interdigital electrode, and the gas-sensitive layer is arranged on the other side of the interdigital electrode. The gas-sensitive layer faces the LED light source.

6. The optically excited semiconductor gas sensor according to claim 5, characterized in that: The ceramic sheet is an alumina-based ceramic material, and the interdigital electrodes are composed of a gold or platinum film layer.

7. The optically excited semiconductor gas sensor according to claim 5, characterized in that: The length of the ceramic sheet is 0.5 mm-1.0 mm, the width of the ceramic sheet is 0.5 mm-1.0 mm, and the thickness of the ceramic sheet is 0.2 mm-0.3 mm.

8. The optically excited semiconductor gas sensor according to claim 5, characterized in that: The gas-sensitive layer is tin oxide, zinc oxide, tungsten oxide, indium oxide or titanium oxide based on semiconductor gas-sensitive ceramic.

9. The optically excited semiconductor gas sensor according to claim 1, characterized in that: The tops of the LED pins and the gas sensor pins are both provided with nail heads, and the tops of the gas sensor pins are higher than the tops of the LED pins.

10. The light-excited semiconductor gas sensor according to claim 1 or 9, characterized in that: The LED pins and the gas sensor pins are both fixedly connected to the base.

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