Sensor sensitive module, ruthenium island enhanced ammonia sensor and ammonia molecule detection method in ammonia gas

Abstract

The invention relates to the field of gas sensing technology. In order to solve the technical problem that the existing ammonia sensor research has encountered a new bottleneck in improving the sensitivity, because the active sites of metal oxide nanoparticles are limited and the decomposition of ammonia molecules cannot be fully catalyzed, the technical solution provided by the present invention is: a sensor sensitive module, the module includes: a bottom gate material layer, a dielectric layer 2 with an isolation function, a channel material layer, a drain material connected to the channel material layer, a dielectric layer 1 with an isolation function, and a sensitive material layer arranged on the surface of the dielectric layer. The bottom gate material layer, the dielectric layer 2 with an isolation function, the channel material layer, the dielectric layer 1 with an isolation function, and the sensitive material layer arranged on the surface of the dielectric layer are stacked tightly in sequence. It can be applied to medical diagnosis, air quality detection, chemical plant safety warning and other fields.

Description

Technical Field

[0001] The invention relates to the field of gas sensing technology. Background Art

[0002] Gas sensing technology has made great contributions to mankind in environmental monitoring, medical diagnosis, industrial safety, etc. Therefore, various types of gas sensors have been continuously researched and developed.

[0003] There are four common gas sensor structures: resistive, optical, electrochemical, and field effect transistor (FET) gas sensors. Resistive gas sensors are one of the most studied types of gas sensors. The target gas is detected by measuring the change in the resistance of the sensor after exposure to the gas. They are cheap and easy to manufacture. Due to the very simple structure, various sensing materials can be easily applied, such as semiconductor metal oxides, carbon nanomaterials, graphene-based materials, transition metal dichalcogenides, etc. Optical sensors generally contain three main parts: light source, gas chamber, and light detector. They have the advantages of high selectivity and fast response, but are difficult to miniaturize, have high cost, and are easily disturbed by ambient light. Electrochemical sensors are low in cost, but have strict requirements on the operating temperature range, short life, and require maintenance and calibration of the electrolyte solution.

[0004] FET-type gas sensors use sensitive materials as gates or channels. When they are exposed to target gases, the threshold voltage of these sensors shifts, causing the source-drain current to change, thereby indicating the target gas concentration. In addition to using sensitive materials as gates, sensitive gate-type sensors can also apply back gates to adjust the channel current. This method can be used to adjust the position of the sensor's initial point on the FET transfer curve to obtain optimized sensor performance.

[0005] Then, in the current research on ammonia sensors, there is a new bottleneck in improving sensitivity. A study on ammonia sensors used metal oxide nanoparticles as the sensitive material of the sensor and integrated them into the field effect transistor (FET) structure. The sensor uses the chemical reaction between ammonia and metal oxide nanoparticles to change the current of the FET, thereby realizing the detection of ammonia. However, the sensor has the problem of low sensitivity because the active sites of metal oxide nanoparticles are limited and cannot fully catalyze the decomposition of ammonia molecules. Summary of the invention

[0006] In order to solve the technical problem that the existing technology has encountered a new bottleneck in improving the sensitivity in the current research of ammonia sensors, because the active sites of metal oxide nanoparticles are limited and cannot fully catalyze the decomposition of ammonia molecules, the technical solution provided by the present invention is:

[0007] A sensor sensitive module, the module comprising:

[0008] A bottom gate material layer, a dielectric layer 2 having an isolation function, a channel material layer, a drain material connected to the channel material layer, a dielectric layer 1 having an isolation function, and a sensitive material layer arranged on the surface of the dielectric layer.

[0009] Furthermore, a preferred embodiment is provided, wherein the bottom gate material layer, the insulating dielectric layer 2, the channel material layer, the insulating dielectric layer 1 and the sensitive material layer arranged on the surface of the dielectric layer are tightly stacked in sequence.

[0010] Furthermore, a preferred embodiment is provided, wherein the drain material contacts an edge of the channel material layer for connecting to a power source.

[0011] Furthermore, a preferred embodiment is provided, wherein the bottom gate material layer is made of highly conductive metal, two-dimensional conductive material or organic conductive material.

[0012] Furthermore, a preferred embodiment is provided, wherein the dielectric layer 2 is used to isolate the bottom gate material layer from the channel material layer, and is made of a material with dielectric properties.

[0013] Furthermore, a preferred embodiment is provided, wherein the channel material layer is made of doped silicon, two-dimensional carbon material, transition metal sulfide or black phosphorus.

[0014] Furthermore, a preferred embodiment is provided, wherein the sensitive material layer is made of island-type Ru material.

[0015] Furthermore, a preferred embodiment is provided, wherein the dielectric layer 1 is used to isolate the channel material layer and the sensitive material layer, and is made of a material with dielectric properties.

[0016] Based on the same inventive concept, the present invention also provides a ruthenium island enhanced ammonia sensor, the sensor comprising: the sensor sensitive module.

[0017] Based on the same inventive concept, the present invention also provides a method for detecting ammonia molecules in ammonia gas, the method is implemented based on the ruthenium island enhanced ammonia sensor, and the method comprises:

[0018] A step of catalytically decomposing ammonia gas to obtain hydrogen atoms;

[0019] The step of allowing the hydrogen atoms to pass through the sensitive material to reach the interface between the sensitive material and the dielectric layer 1;

[0020] The step of collecting the change in current magnitude after the hydrogen atoms adjust the concentration of carriers in the channel material layer.

[0021] Compared with the prior art, the technical solution provided by the present invention is beneficial in that:

[0022] The ruthenium island enhanced ammonia sensor provided by the present invention innovates the structure of the gas sensor to achieve improved sensor sensitivity and further reduced detection limit.

[0023] The ruthenium island enhanced ammonia sensor provided by the present invention uses metal ruthenium as the sensitive grid of the sensor to construct ruthenium islands separated from each other, thereby increasing the number of active sites of ruthenium and improving the sensitivity of the sensor to ammonia.

[0024] The ruthenium island enhanced ammonia sensor provided by the present invention uses various two-dimensional semiconductor materials to construct a field effect transistor (FET), and uses sensitive materials as a gate or channel. When exposed to ammonia, the threshold voltage of the sensor shifts, causing the source-drain current to change, indicating the target gas concentration.

[0025] The ruthenium island enhanced ammonia sensor provided by the present invention realizes a high-sensitivity detection function of ammonia by regulating the gate voltage on the FET source-drain current.

[0026] In the ruthenium island enhanced ammonia sensor provided by the present invention, ammonia molecules are decomposed after being adsorbed on the surface of the ruthenium island, and a part of the hydrogen atoms reach the interface between the ruthenium and the dielectric layer, forming a dipole layer with the electrons of the channel material, thereby changing the current of the FET channel. The amplitude of the current change corresponds to the high and low ammonia concentration.

[0027] The ruthenium island enhanced ammonia sensor provided by the present invention adjusts the initial working point of the sensor to the position with the maximum slope of the transfer curve by adjusting the bottom grid, thereby achieving high-sensitivity detection of low-concentration ammonia.

[0028] The ruthenium island enhanced ammonia sensor provided by the present invention can be applied to medical diagnosis, air quality detection, chemical plant safety warning and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The overall schematic diagram of the ruthenium island enhanced ammonia sensor;

[0030] Figure 2 for Figure 1 A schematic diagram of an implementation example;

[0031] Figure 3 SEM image of Ru island. DETAILED DESCRIPTION

[0032] In order to make the advantages and benefits of the technical solution provided by the present invention more clearly reflected, the technical solution provided by the present invention is now further described in detail with reference to the accompanying drawings, specifically:

[0033] A sensor sensitive module, the module comprising:

[0034] A bottom gate material layer, a dielectric layer 2 having an isolation function, a channel material layer, a drain material connected to the channel material layer, a dielectric layer 1 having an isolation function, and a sensitive material layer arranged on the surface of the dielectric layer.

[0035] Embodiment 2: This embodiment further limits the sensor sensitive module provided in embodiment 1. The bottom gate material layer, the insulating dielectric layer 2, the channel material layer, the insulating dielectric layer 1 and the sensitive material layer arranged on the surface of the dielectric layer are tightly stacked in sequence.

[0036] Embodiment 3: This embodiment further limits the sensor sensitive module provided in Embodiment 2. The drain material contacts the edge of the channel material layer for connecting a power source.

[0037] Embodiment 4: This embodiment further limits the sensor sensitive module provided in Embodiment 1, and the bottom gate material layer is made of high-conductivity metal, two-dimensional conductive material or organic conductive material.

[0038] Embodiment 5: This embodiment further limits the sensor sensitive module provided in Embodiment 1. The dielectric layer 2 is used to isolate the bottom gate material layer from the channel material layer, and is made of a material with dielectric properties.

[0039] Embodiment 6: This embodiment further limits the sensor sensitive module provided in embodiment 1, and the channel material layer is made of doped silicon, two-dimensional carbon material, transition metal sulfide or black phosphorus.

[0040] Embodiment 7: This embodiment further limits the sensor sensitive module provided in Embodiment 1, and the sensitive material layer adopts island-type Ru material.

[0041] Embodiment 8: This embodiment further limits the sensor sensitive module provided in Embodiment 1. The dielectric layer 1 is used to isolate the channel material layer and the sensitive material layer, and is made of a material with dielectric properties.

[0042] Embodiment 9: This embodiment provides a ruthenium island enhanced ammonia sensor, and the sensor includes: the sensor sensitive module provided in embodiment 1.

[0043] Specifically, in response to the bottleneck problem encountered in improving the sensitivity of ammonia sensors, this embodiment provides a FET-type ammonia sensor based on ruthenium island enhancement. Innovations in the structure of the gas sensor are made to improve the sensitivity of the sensor and further reduce the detection limit. Ammonia molecules are decomposed after being adsorbed on the surface of the Ru island, and some hydrogen atoms reach the interface between the Ru island and the dielectric layer, forming a dipole layer with the electrons of the channel material, thereby changing the current of the FET channel. The amplitude of the current change corresponds to the high and low ammonia concentration.

[0044] like Figure 1 The figure shows the core sensitive structure of the designed ammonia sensor, which includes the bottom gate, dielectric layer 2, source-drain electrode and channel, dielectric layer 1, and sensitive material (top gate) from bottom to top.

[0045] Except for the sensitive material which is island type Ru, there are many options for other materials.

[0046] The bottom gate provides a bottom gate for the sensor and adjusts the initial operating point of the sensor. It can use highly doped silicon, highly conductive metals such as gold, silver and copper, two-dimensional conductive materials such as graphene, and organic conductive materials.

[0047] The dielectric layer 2 serves to isolate the bottom gate and the channel material, and may be made of materials with dielectric properties such as silicon oxide, aluminum oxide, boron nitride, high dielectric constant materials (yttrium oxide, hafnium oxide, etc.), and organic insulating materials (polymethyl methacrylate, polyimide, etc.).

[0048] The source and drain electrodes on the sensor substrate mainly serve to connect the channel to the power supply, and can be made of various metals with good conductivity such as gold, silver, copper, etc.

[0049] The channel material can be doped silicon, two-dimensional carbon materials (graphene, carbon nanotube (CNT) film, two-dimensional layered metal carbon / nitride, etc.), transition metal sulfides (such as tin disulfide, molybdenum selenide) and black phosphorus, etc.

[0050] The dielectric layer 1 mainly serves to isolate the channel from the gate current and may be made of materials with dielectric properties such as silicon oxide, aluminum oxide, boron nitride, high dielectric constant materials (yttrium oxide, hafnium oxide, etc.), and organic insulating materials (polymethyl methacrylate, polyimide, etc.).

[0051] Embodiment 10: This embodiment provides a method for detecting ammonia molecules in ammonia gas. The method is implemented based on the ruthenium island enhanced ammonia sensor provided in embodiment 9. The method includes:

[0052] A step of catalytically decomposing ammonia gas to obtain hydrogen atoms;

[0053] The step of allowing the hydrogen atoms to pass through the sensitive material to reach the interface between the sensitive material and the dielectric layer 1;

[0054] The step of collecting the change in current magnitude after the hydrogen atoms adjust the concentration of carriers in the channel material layer.

[0055] Specifically, the working principle of the sensor is as follows:

[0056] 1. A certain production process is used to ensure that the Ru obtained forms isolated islands with more edge positions, which can greatly increase the number of active sites.

[0057] 2. When the sensor is exposed to ammonia, the active sites on the Ru islands catalyze the decomposition of ammonia molecules into nitrogen atoms and hydrogen atoms, some of which move to the interface between Ru and the dielectric layer. The hydrogen atoms form a dipole layer with the electrons in the channel, thereby fixing some of the electrons in the channel. For the n-channel, the number of channel carriers decreases and the current decreases; for the p-channel, the number of carriers increases and the channel current increases.

[0058] 3. The concentration of ammonia will affect the number of fixed electrons, thus establishing a relationship between the amplitude of current change and concentration.

[0059] 4. The bottom gate can adjust the initial operating point of the sensor to the position where the slope of the transfer curve is maximum, so that although the gate voltage change caused by a small amount of ammonia is small, the corresponding current change is still large, thereby achieving an extremely low detection limit.

[0060] 5. Through the description of the working principle of the above sensor, an ammonia sensor with high sensitivity and low detection limit can be realized.

[0061] like Figure 2 and 3 As shown, the materials of each part of the sensor are specialized as an implementation example of this embodiment:

[0062] 1. The bottom gate of the sensor is highly doped silicon, the dielectric layer 2 is silicon oxide, and the upper part thereof is formed with source and drain electrodes by photolithography and thermal evaporation.

[0063] 2. The source and drain electrodes are made of gold.

[0064] 3. The dielectric layer 1 is made of yttrium oxide.

[0065] 4. The channel material is a carbon nanotube film.

[0066] 5. The Ru is obtained by electron beam evaporation using an anodized aluminum template with a pore size of 80 nm as a sacrificial template.

[0067] Through the above-mentioned specific implementation scheme, the manufacture of ammonia sensors enhanced by ruthenium islands can be realized. The hydrogen atoms obtained by the catalytic decomposition of ammonia by Ru islands pass through the sensitive material to the interface between the sensitive material and the dielectric layer 1, and a dipole layer is formed at this interface, thereby adjusting the concentration of carriers in the channel, and the final reaction is a change in the current magnitude. By applying a gate voltage through the bottom gate, the initial operating point of the CNT-FET is adjusted to the maximum slope of the FET transfer curve. A lower ammonia concentration can also cause a large current response, thereby achieving a low detection limit and high sensitivity.

[0068] The technical solution provided by the present invention is further described in detail above through several specific implementation modes in order to highlight the advantages and benefits of the technical solution provided by the present invention. However, the several specific implementation modes described above are not intended to be used as limitations on the present invention. Any reasonable modification and improvement of the present invention, combination of implementation modes and equivalent substitution within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0069] In the description of this specification, only the preferred embodiments of the present invention are provided, and the scope of the rights of the present invention cannot be limited by this. In addition, the description of the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, in the absence of mutual contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

Claims

1. Sensor sensitive module, It is characterized in that The modules include: A bottom gate material layer, a dielectric layer 2 having an isolation function, a channel material layer, a source-drain electrode connected to the channel material layer, a dielectric layer 1 having an isolation function, and a sensitive material layer arranged on the surface of the dielectric layer 1; The sensitive material layer is made of island-type Ru material; The bottom gate material layer, the dielectric layer 2 having an isolation function, the channel material layer, the dielectric layer 1 having an isolation function, and the sensitive material layer arranged on the surface of the dielectric layer 1 are stacked tightly in sequence; The bottom gate material layer is made of highly conductive metal, two-dimensional conductive material or organic conductive material; The dielectric layer 2 is used to isolate the bottom gate material layer from the channel material layer, and is made of a material with dielectric properties; The channel material layer is made of carbon nanotube film; The dielectric layer 1 is used to isolate the channel material layer and the sensitive material layer, and is made of a material with dielectric properties; The Ru islands were obtained by electron beam evaporation using an anodized aluminum template with a pore size of 80 nm as a sacrificial template.

2. The sensor module according to claim 1, It is characterized in that The drain material contacts the edge of the channel material layer and is used for connecting a power source.

3. Ruthenium island enhanced ammonia sensor, It is characterized in that The sensor comprises: the sensor sensitive module as claimed in claim 1.

4. Detection method of ammonia molecules in ammonia gas, It is characterized in that The method is implemented based on the ruthenium island enhanced ammonia sensor according to claim 3, and the method comprises: A step of catalytically decomposing ammonia gas to obtain hydrogen atoms; The step of allowing the hydrogen atoms to pass through the sensitive material to reach the interface between the sensitive material and the dielectric layer 1; The step of collecting the change in current magnitude after the hydrogen atoms adjust the concentration of carriers in the channel material layer.

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