CN105067034B - A kind of graphene/silicon array intelligent Temperature Humidity Sensor - Google Patents

Abstract

The invention discloses a graphene/silicon array type intelligent temperature and humidity sensor. The humidity sensor includes a power supply module, an array type temperature and humidity sensor module, a current detection module, an A/D conversion module, a microprocessor module, and an input module , the output module. The arrayed temperature and humidity sensor module includes an n-type silicon substrate, a silicon dioxide insulating layer, a 2×2 array of silicon windows, graphene, a top electrode and a bottom electrode. The intelligent temperature and humidity sensor of the present invention is based on the graphene/silicon Schottky structure. The graphene/silicon Schottky junction is significantly different from the traditional metal/semiconductor Schottky junction, and has the characteristics of fast multi-substance transmission and sensitive response. . The temperature and humidity sensor of the present invention adopts a unique array structure and can be used in sensors required by devices such as smart phones, smart wearables, and smart homes.

Description

A graphene/silicon array intelligent temperature and humidity sensor

technical field

The invention belongs to the application field of graphene novel multi-parameter intelligent sensors, in particular to a graphene/silicon array type intelligent temperature and humidity sensor.

Background technique

Temperature and humidity are the two main parameters in the human living environment. The temperature of the atmospheric environment can be measured in Celsius, Fahrenheit or absolute temperature; humidity can usually be measured in absolute humidity, relative humidity, and specific humidity. Humidity depends on temperature conditions, so humidity sensors usually also test temperature, forming an integrated temperature and humidity sensor. The temperature and humidity sensor is used to measure the temperature value and relative humidity value under certain temperature conditions. This type of sensor has a great impact on industrial production control, biomedical products, and agricultural automation.

Humidity measurement has always been one of the famous problems in the field of metrology in the world. The reason is that humidity and temperature are a correlation function, and changes in temperature significantly affect the measurement results of humidity. The measurement of humidity involves quite complicated physical-chemical theoretical analysis and equation calculation. Common humidity measurement methods are: dynamic method (dual pressure method, dual temperature method, shunt method), static method (saturated salt method, sulfuric acid method), dew point method, wet and dry bulb method and electronic sensor method.

The traditional dynamic method has high requirements on the cleanliness of the test system and the environment, while the measurement accuracy of the static method is poor. Electronic sensors can be better used in electronic information technology and industry by using semiconductor technology, and the industry demand is large. The present invention The graphene array temperature and humidity sensor belongs to the electronic sensor method. This method measures temperature and humidity at the same time, which improves the sensitivity and accuracy of the sensor.

Contents of the invention

The object of the present invention is to provide a graphene/silicon array intelligent temperature and humidity sensor with high sensitivity and precision, which can be used in an integrated manner.

The graphene/silicon array type intelligent temperature and humidity sensor of the present invention includes a power supply module, an array type temperature and humidity sensor module, a current detection module, an A/D conversion module, a microprocessor module, an input module and an output module;

The input module is used for signal input to provide signal control to the microprocessor module, the current detection module detects the current in the array temperature and humidity sensor module, and transmits the signal to the microprocessor module through the A/D conversion module, and the microprocessor module After processing, the temperature and humidity are output through the output module, and the power module supplies power to each module.

The input module can be a button, a touch screen, bluetooth or a network communication interface.

The output module can be a liquid crystal display screen, a touch screen, bluetooth or a network communication interface.

The arrayed temperature and humidity sensor module includes an n-type silicon substrate and a silicon dioxide isolation layer covering the upper surface of the n-type silicon substrate, and 2×2 silicon windows are opened in an array on the silicon dioxide isolation layer. The upper surface of the silicon dioxide isolation layer around each silicon window is covered with a top electrode, and the upper surface of each silicon window and the corresponding top electrode is covered with graphene, and the boundary of the graphene on each silicon window is smaller than the boundary of the top electrode, A bottom electrode is arranged on the lower surface of the n-type silicon substrate to form a 2×2 array device;

In the above-mentioned 2×2 array device, the two units at one diagonal adopt a closed vacuum packaging structure to avoid the influence of air and light on the device. This part is used as a temperature measurement unit, and the two units at the other diagonal adopt an open package. structure, as a humidity test unit. The current detecting module respectively detects the current signals of the above four units.

The n-type silicon substrate has a resistivity of 1-10 Ω·cm and a thickness of 300-500 μm.

The graphene is single-layer graphene or reduced graphene oxide, and the thickness of the reduced graphene oxide is 1-50nm.

The beneficial effects of the present invention are: the intelligent temperature and humidity sensor of the present invention is based on the graphene/silicon Schottky structure, and the graphene/silicon Schottky junction is significantly different from the traditional metal/semiconductor Schottky junction, except that it has many The transmission speed is fast, the response is sensitive, and graphene is suitable for various applications under unconventional conditions due to its high transparency, high electrical conductivity, high thermal conductivity, and high mechanical strength. The temperature and humidity sensor of the present invention adopts a unique array structure to simultaneously obtain and output temperature and relative humidity. It can be used in sensors required by smart phones, smart wearables, smart homes and other devices. The array structure improves the sensitivity and repeatability, can quickly and easily measure the ambient temperature and humidity, and can even detect the temperature and humidity of the human body for intelligent medical diagnosis, health assistants and other fields.

Description of drawings

Fig. 1 is the structural representation of graphene/silicon array type intelligent temperature and humidity sensor of the present invention;

Fig. 2 is the structural representation of array type temperature and humidity sensor module in the present invention;

3 is a schematic cross-sectional view of an arrayed temperature and humidity sensor module;

In the figure, power supply module (1), input module (2), microprocessor module (3), current detection module (4), array type temperature and humidity sensor module (5), A/D conversion module (6), output Module (7); n-type silicon substrate (51), silicon dioxide isolation layer (52), silicon window (53), graphene (54), top electrode (55) and bottom electrode (56).

detailed description

The present invention will be further described below in conjunction with the accompanying drawings.

Referring to Fig. 1 and Fig. 2, the graphene/silicon array type intelligent temperature and humidity sensor of the present invention comprises a power supply module 1, an array type temperature and humidity sensor module 5, a current detection module 4, an A/D conversion module 6, and a microprocessor module 3 , input module 2 and output module 7;

The input module 2 is used for signal input to provide signal control to the microprocessor module 3, and the current detection module 4 detects the current in the array type temperature and humidity sensor module 5, and passes the signal to the microprocessor module through the A/D conversion module 6 3. The microprocessor module 3 outputs temperature and humidity through the output module 7, and the power supply module 1 supplies power to each module.

The input module 2 can be a button, a touch screen, bluetooth or a network communication interface.

The output module 7 can be a liquid crystal display, a touch screen, bluetooth or a network communication interface.

As shown in Figures 2 and 3, the arrayed temperature and humidity sensor module 5 includes an n-type silicon substrate 51 and a silicon dioxide isolation layer 52 covering the upper surface of the n-type silicon substrate, and the array is formed on the silicon dioxide isolation layer 52. There are 2×2 silicon windows 53 in a formula, and a top electrode 55 is covered on the upper surface of the silicon dioxide isolation layer around each silicon window, and graphene 54 is covered on the upper surface of each silicon window and the corresponding top electrode, The boundary of graphene on each silicon window is smaller than the boundary of the top electrode, and a bottom electrode 56 is arranged on the lower surface of the n-type silicon substrate to form a 2×2 array device; the resistivity of the n-type silicon substrate is 1 to 10 Ω cm, with a thickness of 300-500 μm. The graphene is single-layer graphene or reduced graphene oxide, and the thickness of the reduced graphene oxide is 1-50nm.

In the above-mentioned 2×2 array device, the two units at one diagonal adopt a closed vacuum packaging structure as a temperature measurement unit, and the two units at the other diagonal adopt an open packaging structure as a humidity testing unit; The current detection module 4 respectively detects the current signals of the above four units.

The test signal of the microprocessor module first controls the current detection module to test the current in the two unit groups A located in the diagonal position in the 2×2 array device, and takes the average value of the current of A to convert it into a temperature value, and then controls the test In the 2×2 array device, the current in another pair of two units B located at the diagonal position, taking the temperature value in A into the temperature and humidity current equation, among them, the temperature and humidity current equation:

In a is the temperature coefficient, T is the absolute temperature, b is the humidity coefficient, RH is the relative humidity, ln is the natural logarithmic function, and I is the current value in B. The values of a and b in the equation can be obtained by calibration and fitting. The relative humidity value can be calculated.

The power supply module 1 of the above-mentioned graphene/silicon array type intelligent temperature and humidity sensor provides 5V voltage to supply power to all modules, the array type temperature and humidity sensor works at -5V, and the input module inputs control signals to the microprocessor module to turn on, off, and measure , Zeroing the entire intelligent sensor system, the current detection module tests the current of the array temperature and humidity sensor, and transmits the signal to the microprocessor module through the A/D conversion module, and finally displays the temperature and humidity on the output module.

The method for preparing the core sensor module of the above-mentioned graphene/silicon array type intelligent temperature and humidity sensor comprises the following steps:

(1) The purchased commercial standard 4-inch low-doped n-type single-throw silicon oxide wafer (300 nm SiO2, the resistivity is about 1~10Ω•cm, the thickness of the silicon part is ~500 μm), through acetone solution, isopropanol Sonicate for 3-5 minutes respectively, then use deionized water to sonicate for 5 minutes and blow it clean with high-purity nitrogen, then define the electrode pattern on the silicon wafer through photolithography (one-time photolithography), and then use electron beam evaporation technology to grow thickness A chromium adhesion layer of about 5 nm, and then a 60 nm gold electrode (top electrode) is grown by thermal evaporation technology. The width of the gold electrode is 10-50 μm, followed by stripping and cleaning processes;

(3) Define silicon window pattern by photolithography process (second photolithography), and use standard buffered oxidation etchant BOE solution (NH ₄ F:HF = 6:1), silicon dioxide removed by wet etching ( The etching time is 4 minutes), and the silicon surface is exposed, and the silicon window is a circular hole with a side length of 100-500 μm;

(4) Transfer graphene onto silicon windows and electrodes. Transfer method: evenly spin-coat a layer of photoresist (PR-26) and polymethyl methacrylate (PMMA) film (thickness is about 1 μm) on the surface of copper foil with single-layer graphene, and then put it into the engraved Etching solution (composed of CuSO ₄ , HCl and water, CuSO ₄ : HCl: H ₂ O=10g: 50ml: 50ml) for 4 hours to remove the copper foil, leaving a single layer of graphene supported by PMMA/PR; the PMMA /PR-supported single-layer graphene was cleaned with deionized water (floating in deionized water for 5 minutes, and deionized water was replaced twice), then transferred and tiled to the silica spacer, top electrode, inner wall of the silicon window, The upper surface of the top electrode; after waiting for 2 to 4 hours, remove PMMA and photoresist with acetone and isopropanol, clean them for 5 minutes respectively, and blow them with high-purity nitrogen;

(6) Define the area of graphene through photolithography (three photolithography), so that the photoresist covers the entire metal electrode area, and through oxygen plasma reactive ion etching technology (Oxygen plasma ICP-RIE), its power and The etching time is 75 W, 3 min, etch away the excess graphene outside the photoresist, after the etching is completed, clean with acetone and isopropanol to remove the residual photoresist;

(8) Coat the bottom of the n-type silicon substrate with a gallium-indium eutectic alloy, and use conductive copper foil tape to bond the gold wire to the gallium-indium alloy, and lead out the gold wire to prepare the bottom electrode; wire bonding on the gold electrode on the upper surface The technology leads out the gold wire to complete the preparation of the upper electrode.

The power module 1, input module 2, microprocessor module 3, current detection module 4, A/D conversion module 6, and output module 7 in the graphene/silicon array intelligent temperature and humidity sensor can all use off-the-shelf modules produced by other manufacturers .

Claims (5)

1. a kind of graphene/silicon array intelligent Temperature Humidity Sensor, it is characterised in that including power module（1）, array temperature Moisture sensor module（5）, current detection module（4）, A/D modular converters（6）, microprocessor module（3）, input module（2） And output module（7）；

Input module（2）Controlled with providing signal to microprocessor module (3) for signal input, current detection module（4）Inspection Survey array Temperature Humidity Sensor module（5）In electric current, and by A/D modular converters（6）By signal transmission to microprocessor Module（3）, microprocessor module（3）By output module（7）Output temperature and humidity, power module（1）To each module for power supply；

Described array Temperature Humidity Sensor module（5）Including n-type silicon matrix（51）Be covered in n-type silicon body upper surface Silica separation layer（52）, in silica separation layer（52）Upper array it is provided with 2 × 2 silicon windows（53）, at each The upper surface of the silica separation layer of silicon thereabout covers a top electrode（55）, in each silicon window and corresponding top electrode Upper surface is coated with Graphene（54）, the border of Graphene is less than the border of top electrode on each silicon window, under n-type silicon matrix Surface sets hearth electrode（56）, form 2 × 2 array devices；

Diagonal two unit uses closed vacuum encapsulating structure in 2 × 2 above-mentioned array devices, used as thermometric Unit, another two diagonal units use open encapsulating structure, used as humidity measurement unit；Described current detection module （4）The current signal of aforementioned four unit is detected respectively.

2. graphene/silicon array intelligent Temperature Humidity Sensor according to claim 1, it is characterised in that described is defeated Enter module（2）It is button, touch-screen, bluetooth or network communication interface.

3. graphene/silicon array intelligent Temperature Humidity Sensor according to claim 1, it is characterised in that described is defeated Go out module（7）It is LCDs, touch-screen, bluetooth or network communication interface.

4. graphene/silicon array intelligent Temperature Humidity Sensor according to claim 1, it is characterised in that described n The resistivity of type silicon substrate is 1 ~ 10 Ω cm, and thickness is 300 ~ 500 μm.

5. graphene/silicon array intelligent Temperature Humidity Sensor according to claim 1, it is characterised in that described stone Black alkene is single-layer graphene or redox graphene, and described redox graphene thickness is 1-50nm.