CN109324088A - The heterogeneous multilevel structure of silicon nanowires and its preparation method and application of netted tungsten oxide nano modification - Google Patents
The heterogeneous multilevel structure of silicon nanowires and its preparation method and application of netted tungsten oxide nano modification Download PDFInfo
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- CN109324088A CN109324088A CN201710640185.6A CN201710640185A CN109324088A CN 109324088 A CN109324088 A CN 109324088A CN 201710640185 A CN201710640185 A CN 201710640185A CN 109324088 A CN109324088 A CN 109324088A
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
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- G01N27/127—Composition of the body, e.g. the composition of its sensitive layer comprising nanoparticles
Abstract
The present invention provides the heterogeneous multilevel structure of silicon nanowires and its preparation method and application of netted tungsten oxide nano modification, carries out as steps described below: metal Assisted Chemical Etching Process method etching silicon nano line array, the sparse of silicon nanowire array, roughening treatment, the preparation of tungsten oxide seed layer and netted tungsten oxide nano hydrothermal growth.Based on the laminar composite of one-dimensional nano line due to unique high activity surface structure, it is very suitable for gas sensor, the heterogeneous multilevel structure of silicon nanowires of netted tungsten oxide nano modification is because of its special heterojunction structure, conductivity and carrier transport ability are enhanced, so at normal temperature to NO2There is stronger sensitive response.The structure can detect NO at normal temperature2Gas extends sensor life-time in gas sensor and ic process compatibility, and energy saving and hazardous gas context of detection have critically important researching value.
Description
Technical field
The present invention relates to semiconductor gas sensor technical fields, more specifically to a kind of netted tungsten oxide nano
Heterogeneous multilevel structure of the silicon nanowires of modification and its preparation method and application, which is exposed to NO at normal temperature2Environment, resistance
Resistance value can be decreased obviously, so as to detect NO at normal temperature2Gas, the structure are simultaneous with integrated circuit technology in gas sensor
Hold, extend sensor life-time, energy saving and hazardous gas context of detection have critically important researching value.
Background technique
With the development of the social economy, the environment that we depend on for existence has paid huge cost, the burning of a large amount of fuel,
The discharge and industrial processes of vehicle exhaust produce a large amount of toxic and harmful gas, wherein NO2Harm it is very important.NO2
Cause atmosphere, water body and soil pollution, atmospheric visibility can be made to reduce, and it is one of origin cause of formation of acid rain, make water acidification,
Eutrophication.NO simultaneously2Toxicity itself can greatly be detrimental to health, and cause the respiratory disorders such as pulmonary edema.China provides ring
NO in border2Concentration should be lower than 120ppb, therefore the NO that processability is excellent2Gas sensor is realized to toxicity NO2The reality of gas
Shi Youxiao reliably detects very urgent.High performance nano-sensor is obtained, will prepare can provide these height first
The nano material of performance possibility.
In air-sensitive field, up to the present, different semiconductor materials such as silicon nanowires and various metal oxides are especially
It is that tungsten oxide etc. has the advantages that at low cost and high sensitivity, is generally considered the gas sensitive for most having development and application prospect.
The NO of metal oxide and Old plant2Gas, but its higher operating temperature (general 100-300 DEG C) are passed to modern
The low-power consumption of sensor brings huge challenge.In recent years, in the application of low-power consumption sensor, silicon nanowires can as one kind
The gas sensor material for having good prospect to work at room temperature, silicon nanowires have drawn in the low-power consumption application of sensor
Play more and more concerns.Other apparent advantages of silicon nanowire sensor further include be easy to other silicon-based devices collection and
It is manufactured on silicon crystal unit.
According to previous studies have shown that adulterating or formed compound gas sensitive is to reduce tungsten oxide material operating temperature
A kind of effective way, and can be further improved to NO2Sensitivity and selectivity.Therefore preparing composite air-sensitive material is
Realize that room temperature detects low concentration of NO2Effective way.
Summary of the invention
The present invention overcomes deficiencies in the prior art, provide a kind of silicon nanowires of netted tungsten oxide nano modification
Heterogeneous multilevel structure and its preparation method and application, the structure can be sensitive to NO2 at normal temperature, can be used for the detection of NO2, in gas
Body sensor and ic process compatibility, extend sensor life-time, and energy saving and hazardous gas context of detection have very
Important researching value.
The purpose of the present invention is achieved by following technical proposals.
The heterogeneous multilevel structure of silicon nanowires and preparation method thereof of netted tungsten oxide nano modification, as steps described below into
Row:
Step 1, metal Assisted Chemical Etching Process method etching silicon nano line array: silver nitrate is dissolved in hydrofluoric acid solution, institute
Obtaining hydrofluoric acid concentration in solution is 5-5.5M, and silicon wafer is impregnated 1- by silver nitrate concentration 0.025-0.030M in the above solution
It is put into 5-20min in the aqueous solution of nitric acid of mass percent 30% after 4h, is then rinsed well with deionized water；
Step 2, sparse, the roughening treatment of silicon nanowire array: after silicon wafer made from step 1 is cleaned with deionized water
1-5min is impregnated in the hydrofluoric acid aqueous solution of mass percent 5-10%, after then being cleaned again with deionized water, in quality
20-30s are impregnated in the KOH aqueous solution of percentage 10-20%, by secondarily etched, so that silicon nanowire array becomes sparse
And rough surface, to be conducive to the attachment and gas diffusion of following tungsten oxide seed；
Step 3, the preparation of tungsten oxide seed layer: tungsten oxide seed drop is gone forward side by side on the silicon nanowires that step 2 obtains
Row spin coating drying, then sample is placed in Muffle furnace at 600-700 DEG C and is heat-treated 1-3h, i.e., oxidation is formed on silicon nanowires
Tungsten seed layer, wherein tungsten oxide seed liquor is prepared as steps described below: sodium tungstate is evenly dispersed in deionized water, drop
Add hydrochloric acid to there is not white precipitate, is got a yellowish precipitate after centrifugation, pale yellow precipitate is dissolved in aqueous hydrogen peroxide solution
In, it is configured to seed liquor；
Step 4, the hydrothermal growth of netted tungsten oxide nano: the sample that seed layer is had made from step 3 is just being faced
Under be put into the liner equipped with hydro-thermal reaction liquid, liner is placed in reaction kettle, then 160-200 DEG C of heat treatment 6- in an oven
After 10h, it is down to 20-25 DEG C of room temperature, after cleaning, 60-100 DEG C of dry 8-12h, obtains netted tungsten oxide nano in an oven
The heterogeneous multilevel structure of the silicon nanowires of modification；Hydro-thermal reaction heat is prepared as steps described below: sodium tungstate is dispersed in
In deionized water, salt acid for adjusting pH is instilled to 1-2, by the evenly dispersed solution of ammonium sulfate and magnetic agitation, obtain hydrothermal solution,
Sodium tungstate dosage is 10-14 mass parts, and ammonium sulfate dosage is 9-12 mass parts, and each mass parts are 1g.
Obtained through above-mentioned preparation method netted tungsten oxide nano modification the heterogeneous multilevel structure of silicon nanowires in, by
In the array of silicon nanowires composition, reticular structure is presented in tungsten oxide nano, and is coated on silicon nanowires, and silicon nanowires is long
20-32 μm, 1-2 μm of diameter, the long 25-30 μ of tungsten oxide nanometer wire length 400-1200nm, 18-30nm of diameter, preferably silicon nanowires
M, 1-1.5 μm of diameter, tungsten oxide nanometer wire length 600-800nm, 20-25nm of diameter.
Such as attached drawing testing result, there are silicon and tungstic acid in multilevel structure, and spacing of lattice 0.3-0.4nm, it is crystal orientation
002 monoclinic crystal.
In step 1, single-sided polishing silicon wafer the cleaning of silicon wafer: is impregnated into 30- in the concentrated sulfuric acid and hydrogen peroxide of 3:1
50min is subsequently placed in hydrofluoric acid solution and impregnates 5-10min, and then successively ultrasound is clear respectively in acetone solvent, dehydrated alcohol
After washing 5-10min, it is placed in infrared baking oven and thoroughly dries.
In step 1, silicon wafer is single-sided polishing p-type lightly doped silicon wafer, and crystal orientation is (100), and resistivity is 10-15 Ω .cm,
Silicon wafer cut lengths are 20mm × 10mm.
In step 3, specifically, 1.65g sodium tungstate is dissolved in 100ml deionized water, magnetic agitation 10min, dropwise
It is added 6MHCL (aqueous solution of hydrogen chloride), until there is not white precipitate, after being centrifuged 50min, gets a yellowish precipitate, incite somebody to action
Above-mentioned pale yellow precipitate is dissolved in hydrogen peroxide (aqueous hydrogen peroxide solution of mass percent 10-30%), and it is dense to be configured to solution
Degree is the seed liquor of 1-2M.
In step 3, spin coating 30-50s, flash baking 5-10min are carried out using sol evenning machine, repeats spin coating, drying 4-6 times
After be heat-treated.
In step 3, the condition of heat treatment are as follows: heat treatment temperature is 640-660 DEG C, heat treatment time 1.5-2.5h.
In step 4, sodium tungstate dosage is 10-12 mass parts, and ammonium sulfate dosage is 9-10 mass parts, each mass parts
For 1g；Specifically, 12.38g sodium tungstate is dissolved in 250ml deionized water, magnetic agitation 10min, instills 6M HCL tune dropwise
PH to 1-2 is saved, hydrothermal solution is obtained after 9.911g ammonium sulfate is dissolved in solution and magnetic agitation 10min, takes the above-mentioned hydro-thermal of 60ml
Solution is into the liner of 100ml.
In step 4, the sample with seed layer is down to room temperature 20-25 in an oven after 170-190 DEG C of heat treatment 7-9h
DEG C, after cleaning, 70-90 DEG C of dry 9-11h in an oven.
It (is modified based on netted tungsten oxide nano using the process that the heterogeneous multilevel structure of silicon nanowires prepares gas sensor
The heterogeneous multilevel structure of silicon nanowires gas sensor): the heterogeneous multistage knot of the silicon nanowires that netted tungsten oxide nano is modified
Structure platinized electrode, forming two spacing on the compound heterogeneous multilevel structure of silicon nanowires/tungsten oxide nano by template is
0.5-3cm, size are the electrode of 1-3mm*1-3mm, form the Ohmic contact between electrode and silicon chip surface nano wire, the gold of use
Belong to platinum as sputtering target material, argon gas is as working gas, and sputtering time 1-4min, forming thickness of electrode is 80-120nm.
The quality purity of argon working gas is 99.999%, and the quality purity of target metal platinum is 99.95%, and ontology is true
Sky 1.0 × 10-2Pa or less.
The heterogeneous multilevel structure of the silicon nanowires can sensitively detect NO at normal temperature2, right at 20-25 DEG C of room temperature
1ppm-5ppm NO2Gas-dynamic response as shown in figure 5, be exposed to 1ppm at room temperature, 3ppm, 5ppm NO2It is sensitive under gas
Spend (resistance value in sensitivity=air under resistance value/detection gas of gas sensor) respectively: 1.47,1.67,2.46, response
Time average (time used in resistance variations 90%) is less than 1s, recovery time (time used in resistance variations 90%) average out to
100-160s, the compound heterogeneous multilevel structure air-sensitive sensing element is at normal temperature to the response of gas with various as shown in fig. 6, performance
Go out to NO2Good selectivity.
The invention has the benefit that based on the laminar composite of one-dimensional nano line due to unique high activity table
Face structure is very suitable for gas sensor, the heterogeneous multilevel structure Yin Qite of silicon nanowires of netted tungsten oxide nano modification
Different heterojunction structure enhances conductivity and carrier transport ability, so at normal temperature to NO2There is stronger sensitive sound
It answers.The structure can detect NO at normal temperature2Gas extends sensor life-time in gas sensor and ic process compatibility,
Energy saving and hazardous gas context of detection have critically important researching value.
Detailed description of the invention
Fig. 1 is the scanning electron microscope plan view of the heterogeneous multilevel structure of silicon nanowires of netted tungsten oxide nano modification
And its enlarged drawing；
Fig. 2 is the scanning electron microscope cross-section diagram of the heterogeneous multilevel structure of silicon nanowires of netted tungsten oxide nano modification
And its enlarged drawing；
Fig. 3 is the XRD result phenogram of the heterogeneous multilevel structure of silicon nanowires of netted tungsten oxide nano modification；
Fig. 4 is the TEM result phenogram of single tungsten oxide nano；
Fig. 5 is the heterogeneous multilevel structure of silicon nanowires of netted tungsten oxide nano modification to 1-5ppm NO2Dynamic response
Figure；
Fig. 6 is sensitivity map of the heterogeneous multilevel structure of silicon nanowires to gas with various of netted tungsten oxide nano modification.
Specific embodiment
Below by specific embodiment, further description of the technical solution of the present invention.
Embodiment 1
(1) cleaning of monocrystalline silicon piece
Single-sided polishing silicon wafer is impregnated into 30min in the concentrated sulfuric acid and hydrogen peroxide of 3:1, is then placed in hydrofluoric acid solution and soaks
5min is steeped, then successively ultrasound is respectively washed 5min in acetone solvent, dehydrated alcohol, removes surface and oil contaminant and organic matter is miscellaneous
Matter is placed in infrared baking oven and thoroughly dries.
(2) metal Assisted Chemical Etching Process method etching silicon nano line array
A certain amount of silver nitrate is dissolved in certain density hydrofluoric acid solution, hydrofluoric acid concentration is 5M in acquired solution,
Silver nitrate concentration is 0.025M.Cleaned silicon wafer is impregnated to 5min in the nitric acid solution for be put into after 1h 30% in the above solution
For removing the impurity of silicon chip surface, then rinsed well with deionized water.
(3) sparse, the roughening treatment of silicon nanowire array
1min is impregnated in 5% hydrofluoric acid solution after silicon wafer made from step (2) is cleaned with deionized water, then again
After being cleaned with deionized water, 20s is impregnated in 20% KOH solution, by secondarily etched, so that silicon nanowire array becomes dilute
Thin and rough surface, to be conducive to the attachment and gas diffusion of following tungsten oxide seed.
(4) preparation of tungsten oxide seed layer
1.65g sodium tungstate is dissolved in 100ml deionized water, 6M HCL is added dropwise in magnetic agitation 10min, until not existing
There is white precipitate.Centrifuge is centrifuged 50min, gets a yellowish precipitate.Pale yellow precipitate is dissolved in hydrogen peroxide, is configured to
Solution concentration is the seed liquor of 1M.By seed drop on the silicon nanowires that step (3) obtains, using sol evenning machine spin coating 30s, fastly
Sample is put into Muffle furnace after repeating spin coating, drying 4 times, 1h is heat-treated at 600 DEG C, i.e., in silicon nanowires by speed drying 5min
Upper formation tungsten oxide seed layer.
(5) hydro-thermal reaction liquid is configured
12.38g sodium tungstate is dissolved in 250ml deionized water, magnetic agitation 10min, dropwise instill 6M HCL adjust PH to
9.911g ammonium sulfate is dissolved in solution and magnetic agitation 10min by 1-2.
(6) hydrothermal growth of netted tungsten oxide nano
Take solution made from 60ml step (5) into the liner of 100ml, by step (4) sample obtained for having seed layer
Product face down is put into liner, and apart from liner bottom about 1/3, liner is placed in reaction kettle.Then 160 DEG C of heat in an oven
After handling 6h, it is down to 20-25 DEG C of room temperature, after cleaning, in an oven 60 DEG C of dry 8h, obtains netted tungsten oxide nano modification
The heterogeneous multilevel structure of silicon nanowires.
(7) electrode is prepared
It is compound heterogeneous in silicon nanowires/tungsten oxide nano by template by the silicon wafer platinized electrode after step (6)
It is 0.5cm that two spacing are formed on multilevel structure, and size is the electrode of 1mm*1mm, is formed between electrode and silicon chip surface nano wire
Ohmic contact, as sputtering target material, argon gas is the metal platinum of use as working gas, the quality purity of argon working gas
99.999%, the quality purity of target metal platinum is 99.95%, ontology vacuum 1.0 × 10-2Pa is hereinafter, sputtering time 1min, shape
It is 80nm at thickness of electrode.
Embodiment 2
(1) cleaning of monocrystalline silicon piece
Single-sided polishing silicon wafer is impregnated into 50min in the concentrated sulfuric acid and hydrogen peroxide of 3:1, is then placed in hydrofluoric acid solution and soaks
10min is steeped, then successively ultrasound is respectively washed 10min in acetone solvent, dehydrated alcohol, removes surface and oil contaminant and organic matter is miscellaneous
Matter is placed in infrared baking oven and thoroughly dries.
(2) metal Assisted Chemical Etching Process method etching silicon nano line array
A certain amount of silver nitrate is dissolved in certain density hydrofluoric acid solution, hydrofluoric acid concentration is in acquired solution
5.5M, silver nitrate concentration 0.030M.Cleaned silicon wafer is impregnated in the above solution be put into after 4h 30% nitric acid solution
Middle 20min is used to remove the impurity of silicon chip surface, is then rinsed well with deionized water.
(3) sparse, the roughening treatment of silicon nanowire array
1min is impregnated in 5% hydrofluoric acid solution after silicon wafer made from step (2) is cleaned with deionized water, then again
After being cleaned with deionized water, 20s is impregnated in 20% KOH solution, by secondarily etched, so that silicon nanowire array becomes dilute
Thin and rough surface, to be conducive to the attachment and gas diffusion of following tungsten oxide seed.
(4) preparation of tungsten oxide seed layer
1.65g sodium tungstate is dissolved in 100ml deionized water, 6M HCL is added dropwise in magnetic agitation 10min, until not existing
There is white precipitate.Centrifuge is centrifuged 50min, gets a yellowish precipitate.Pale yellow precipitate is dissolved in hydrogen peroxide, is configured to
Solution concentration is the seed liquor of 2M.By seed drop on the silicon nanowires that step (3) obtains, using sol evenning machine spin coating 50s, fastly
Sample is put into Muffle furnace after repeating spin coating, drying 6 times, 3h is heat-treated at 700 DEG C, i.e., in silicon nanometer by speed drying 10min
Tungsten oxide seed layer is formed on line.
(5) hydro-thermal reaction liquid is configured
12.38g sodium tungstate is dissolved in 250ml deionized water, magnetic agitation 10min, dropwise instill 6M HCL adjust PH to
9.911g ammonium sulfate is dissolved in solution and magnetic agitation 10min by 1-2.
(6) hydrothermal growth of netted tungsten oxide nano
Take solution made from 60ml step (5) into the liner of 100ml, by step (4) sample obtained for having seed layer
Product face down is put into liner, and apart from liner bottom about 1/3, liner is placed in reaction kettle.Then 200 DEG C of heat in an oven
After handling 10h, it is down to 20-25 DEG C of room temperature, after cleaning, 100 DEG C of dry 12h, obtain netted tungsten oxide nano in an oven
The heterogeneous multilevel structure of the silicon nanowires of modification.
(7) electrode is prepared
It is compound heterogeneous in silicon nanowires/tungsten oxide nano by template by the silicon wafer platinized electrode after step (6)
It is 3cm that two spacing are formed on multilevel structure, and size is the electrode of 3mm*3mm, is formed between electrode and silicon chip surface nano wire
Ohmic contact, as sputtering target material, argon gas is the metal platinum of use as working gas, the quality purity of argon working gas
99.999%, the quality purity of target metal platinum is 99.95%, ontology vacuum 1.0 × 10-2Pa is hereinafter, sputtering time 4min, shape
It is 120nm at thickness of electrode.
Embodiment 3
(1) cleaning of monocrystalline silicon piece
Single-sided polishing silicon wafer is impregnated into 40min in the concentrated sulfuric acid and hydrogen peroxide of 3:1, is then placed in hydrofluoric acid solution and soaks
6min is steeped, then successively ultrasound is respectively washed 8min in acetone solvent, dehydrated alcohol, removes surface and oil contaminant and organic matter is miscellaneous
Matter is placed in infrared baking oven and thoroughly dries.
(2) metal Assisted Chemical Etching Process method etching silicon nano line array
A certain amount of silver nitrate is dissolved in certain density hydrofluoric acid solution, hydrofluoric acid concentration is in acquired solution
5.2M, silver nitrate concentration 0.026M.Cleaned silicon wafer is impregnated in the above solution be put into after 2.5h 30% nitric acid it is molten
10min is used to remove the impurity of silicon chip surface in liquid, is then rinsed well with deionized water.
(3) sparse, the roughening treatment of silicon nanowire array
1min is impregnated in 5% hydrofluoric acid solution after silicon wafer made from step (2) is cleaned with deionized water, then again
After being cleaned with deionized water, 20s is impregnated in 20% KOH solution, by secondarily etched, so that silicon nanowire array becomes dilute
Thin and rough surface, to be conducive to the attachment and gas diffusion of following tungsten oxide seed.
(4) preparation of tungsten oxide seed layer
1.65g sodium tungstate is dissolved in 100ml deionized water, 6M HCL is added dropwise in magnetic agitation 10min, until not existing
There is white precipitate.Centrifuge is centrifuged 50min, gets a yellowish precipitate.Pale yellow precipitate is dissolved in hydrogen peroxide, is configured to
Solution concentration is the seed liquor of 1.5M.By seed drop on the silicon nanowires that step (3) obtains, using sol evenning machine spin coating 40s,
Sample is put into Muffle furnace after repeating spin coating, drying 5 times, 2h is heat-treated at 650 DEG C, i.e., in silicon nanometer by flash baking 8min
Tungsten oxide seed layer is formed on line.
(5) hydro-thermal reaction liquid is configured
12.38g sodium tungstate is dissolved in 250ml deionized water, magnetic agitation 10min, dropwise instill 6M HCL adjust PH to
9.911g ammonium sulfate is dissolved in solution and magnetic agitation 10min by 1-2.
(6) hydrothermal growth of netted tungsten oxide nano
Take solution made from 60ml step (5) into the liner of 100ml, by step (4) sample obtained for having seed layer
Product face down is put into liner, and apart from liner bottom about 1/3, liner is placed in reaction kettle.Then 180 DEG C of heat in an oven
After handling 8h, it is down to 20-25 DEG C of room temperature, after cleaning, 80 DEG C of dry 10h, obtain netted tungsten oxide nano and repair in an oven
The heterogeneous multilevel structure of the silicon nanowires of decorations.
(7) electrode is prepared
It is compound heterogeneous in silicon nanowires/tungsten oxide nano by template by the silicon wafer platinized electrode after step (6)
It is 2cm that two spacing are formed on multilevel structure, and size is the electrode of 2mm*2mm, is formed between electrode and silicon chip surface nano wire
Ohmic contact, as sputtering target material, argon gas is the metal platinum of use as working gas, the quality purity of argon working gas
99.999%, the quality purity of target metal platinum is 99.95%, ontology vacuum 1.0 × 10-2Pa is hereinafter, sputtering time 2min, shape
It is 100nm at thickness of electrode.
Embodiment 4
(1) cleaning of monocrystalline silicon piece
Single-sided polishing silicon wafer is impregnated into 35min in the concentrated sulfuric acid and hydrogen peroxide of 3:1, is then placed in hydrofluoric acid solution and soaks
6min is steeped, then successively ultrasound is respectively washed 9min in acetone solvent, dehydrated alcohol, removes surface and oil contaminant and organic matter is miscellaneous
Matter is placed in infrared baking oven and thoroughly dries.
(2) metal Assisted Chemical Etching Process method etching silicon nano line array
A certain amount of silver nitrate is dissolved in certain density hydrofluoric acid solution, hydrofluoric acid concentration is in acquired solution
5.4M, silver nitrate concentration 0.027M.Cleaned silicon wafer is impregnated in the above solution be put into after 2.5h 30% nitric acid it is molten
15min is used to remove the impurity of silicon chip surface in liquid, is then rinsed well with deionized water.
(3) sparse, the roughening treatment of silicon nanowire array
1min is impregnated in 5% hydrofluoric acid solution after silicon wafer made from step (2) is cleaned with deionized water, then again
After being cleaned with deionized water, 20s is impregnated in 20% KOH solution, by secondarily etched, so that silicon nanowire array becomes dilute
Thin and rough surface, to be conducive to the attachment and gas diffusion of following tungsten oxide seed.
(4) preparation of tungsten oxide seed layer
1.65g sodium tungstate is dissolved in 100ml deionized water, 6M HCL is added dropwise in magnetic agitation 10min, until not existing
There is white precipitate.Centrifuge is centrifuged 50min, gets a yellowish precipitate.Pale yellow precipitate is dissolved in hydrogen peroxide, is configured to
Solution concentration is the seed liquor of 2M.By seed drop on the silicon nanowires that step (3) obtains, using sol evenning machine spin coating 35s, fastly
Sample is put into Muffle furnace after repeating spin coating, drying 5 times, 1.5h is heat-treated at 680 DEG C, i.e., in silicon nanometer by speed drying 6min
Tungsten oxide seed layer is formed on line.
(5) hydro-thermal reaction liquid is configured
12.38g sodium tungstate is dissolved in 250ml deionized water, magnetic agitation 10min, dropwise instill 6M HCL adjust PH to
9.911g ammonium sulfate is dissolved in solution and magnetic agitation 10min by 1-2.
(6) hydrothermal growth of netted tungsten oxide nano
Take solution made from 60ml step (5) into the liner of 100ml, by step (4) sample obtained for having seed layer
Product face down is put into liner, and apart from liner bottom about 1/3, liner is placed in reaction kettle.Then 170 DEG C of heat in an oven
After handling 7h, it is down to 20-25 DEG C of room temperature, after cleaning, in an oven 70 DEG C of dry 9h, obtains netted tungsten oxide nano modification
The heterogeneous multilevel structure of silicon nanowires.
(7) electrode is prepared
It is compound heterogeneous in silicon nanowires/tungsten oxide nano by template by the silicon wafer platinized electrode after step (6)
It is 1cm that two spacing are formed on multilevel structure, and size is the electrode of 1.5mm*1.5mm, forms electrode and silicon chip surface nano wire
Between Ohmic contact, the metal platinum of use is as sputtering target material, and argon gas is as working gas, the quality purity of argon working gas
It is 99.999%, the quality purity of target metal platinum is 99.95%, ontology vacuum 1.0 × 10-2Pa hereinafter, sputtering time 3min,
Formation thickness of electrode is 90nm.
Embodiment 5
(1) cleaning of monocrystalline silicon piece
Single-sided polishing silicon wafer is impregnated into 45min in the concentrated sulfuric acid and hydrogen peroxide of 3:1, is then placed in hydrofluoric acid solution and soaks
9min is steeped, then successively ultrasound is respectively washed 8min in acetone solvent, dehydrated alcohol, removes surface and oil contaminant and organic matter is miscellaneous
Matter is placed in infrared baking oven and thoroughly dries.
(2) metal Assisted Chemical Etching Process method etching silicon nano line array
A certain amount of silver nitrate is dissolved in certain density hydrofluoric acid solution, hydrofluoric acid concentration is in acquired solution
5.5M, silver nitrate concentration 0.030M.Cleaned silicon wafer is impregnated in the above solution be put into after 3.5h 30% nitric acid it is molten
16min is used to remove the impurity of silicon chip surface in liquid, is then rinsed well with deionized water.
(3) sparse, the roughening treatment of silicon nanowire array
1min is impregnated in 5% hydrofluoric acid solution after silicon wafer made from step (2) is cleaned with deionized water, then again
After being cleaned with deionized water, 20s is impregnated in 20% KOH solution, by secondarily etched, so that silicon nanowire array becomes dilute
Thin and rough surface, to be conducive to the attachment and gas diffusion of following tungsten oxide seed.
(4) preparation of tungsten oxide seed layer
1.65g sodium tungstate is dissolved in 100ml deionized water, 6M HCL is added dropwise in magnetic agitation 10min, until not existing
There is white precipitate.Centrifuge is centrifuged 50min, gets a yellowish precipitate.Pale yellow precipitate is dissolved in hydrogen peroxide, is configured to
Solution concentration is the seed liquor of 1-2M.By seed drop on the silicon nanowires that step (3) obtains, using sol evenning machine spin coating 48s,
Sample is put into Muffle furnace after repeating spin coating, drying 6 times, 1.5h is heat-treated at 690 DEG C, i.e., receive in silicon by flash baking 9min
Tungsten oxide seed layer is formed on rice noodles.
(5) hydro-thermal reaction liquid is configured
12.38g sodium tungstate is dissolved in 250ml deionized water, magnetic agitation 10min, dropwise instill 6M HCL adjust PH to
9.911g ammonium sulfate is dissolved in solution and magnetic agitation 10min by 1-2.
(6) hydrothermal growth of netted tungsten oxide nano
Take solution made from 60ml step (5) into the liner of 100ml, by step (4) sample obtained for having seed layer
Product face down is put into liner, and apart from liner bottom about 1/3, liner is placed in reaction kettle.Then 190 DEG C of heat in an oven
After handling 9h, it is down to 20-25 DEG C of room temperature, after cleaning, 90 DEG C of dry 11h, obtain netted tungsten oxide nano and repair in an oven
The heterogeneous multilevel structure of the silicon nanowires of decorations.
(7) electrode is prepared
It is compound heterogeneous in silicon nanowires/tungsten oxide nano by template by the silicon wafer platinized electrode after step (6)
It is 2.5cm that two spacing are formed on multilevel structure, and size is the electrode of 2.5mm*2.5mm, forms electrode and silicon chip surface nanometer
Ohmic contact between line, the metal platinum of use is as sputtering target material, and for argon gas as working gas, the quality of argon working gas is pure
Degree is 99.999%, and the quality purity of target metal platinum is 99.95%, ontology vacuum 1.0 × 10-2Pa is hereinafter, sputtering time
3min, forming thickness of electrode is 110nm.
The adjustment of technological parameter is carried out according to the content of present invention contents, and the system of multilevel structure in the present invention can be achieved
It is standby, and show the gas sensing property for nitrogen dioxide.Illustrative description has been done to the present invention above, it should explanation,
In the case where not departing from core of the invention, any simple deformation, modification or other skilled in the art can not be spent
The equivalent replacement of expense creative work each falls within protection scope of the present invention.
Claims (10)
1. the heterogeneous multilevel structure of silicon nanowires of netted tungsten oxide nano modification, which is characterized in that formed by silicon nanowires
Array in, reticular structure is presented in tungsten oxide nano, and is coated on silicon nanowires, and silicon nanowires is 20-32 μm long, diameter 1-
2 μm, tungsten oxide nanometer wire length 400-1200nm, 18-30nm of diameter.
2. the heterogeneous multilevel structure of silicon nanowires of netted tungsten oxide nano modification according to claim 1, feature exist
In, silicon nanowires is 25-30 μm long, and 1-1.5 μm of diameter, tungsten oxide nanometer wire length 600-800nm, 20-25nm of diameter.
3. the preparation method of the heterogeneous multilevel structure of silicon nanowires of netted tungsten oxide nano modification, which is characterized in that according to
Following step carries out:
Step 1, metal Assisted Chemical Etching Process method etching silicon nano line array: silver nitrate is dissolved in hydrofluoric acid solution, gained is molten
Hydrofluoric acid concentration is 5-5.5M, silver nitrate concentration 0.025-0.030M, after silicon wafer is impregnated 1-4h in the above solution in liquid
It is put into 5-20min in the aqueous solution of nitric acid of mass percent 30%, is then rinsed well with deionized water；
Step 2, sparse, the roughening treatment of silicon nanowire array: in matter after silicon wafer made from step 1 is cleaned with deionized water
It measures and impregnates 1-5min in the hydrofluoric acid aqueous solution of percentage 5-10%, after then being cleaned again with deionized water, in quality percentage
20-30s are impregnated in the KOH aqueous solution of number 10-20%, by secondarily etched, so that the sparse and table that silicon nanowire array becomes
Face is coarse, to be conducive to the attachment and gas diffusion of following tungsten oxide seed；
Step 3, the preparation of tungsten oxide seed layer: tungsten oxide seed drop on the silicon nanowires that step 2 obtains and is carried out even
Glue drying, then sample is placed in Muffle furnace at 600-700 DEG C and is heat-treated 1-3h, i.e., tungsten oxide kind is formed on silicon nanowires
Sublayer, wherein tungsten oxide seed liquor is prepared as steps described below: sodium tungstate is evenly dispersed in deionized water, salt is added dropwise
Acid gets a yellowish precipitate after centrifugation to there is not white precipitate, pale yellow precipitate is dissolved in aqueous hydrogen peroxide solution, match
It is set to seed liquor；
Step 4, the hydrothermal growth of netted tungsten oxide nano: the sample face down that seed layer is had made from step 3 is put
Enter in the liner equipped with hydro-thermal reaction liquid, liner is placed in reaction kettle, then 160-200 DEG C of heat treatment 6-10h in an oven
Afterwards, it is down to 20-25 DEG C of room temperature, after cleaning, in an oven 60-100 DEG C of dry 8-12h, obtains netted tungsten oxide nano and repairs
The heterogeneous multilevel structure of the silicon nanowires of decorations；Hydro-thermal reaction heat is prepared as steps described below: sodium tungstate is dispersed in
In ionized water, salt acid for adjusting pH is instilled to 1-2, by the evenly dispersed solution of ammonium sulfate and magnetic agitation, obtain hydrothermal solution, tungsten
Sour sodium dosage is 10-14 mass parts, and ammonium sulfate dosage is 9-12 mass parts.
4. its preparation side of the heterogeneous multilevel structure of silicon nanowires of netted tungsten oxide nano modification according to claim 3
Method, which is characterized in that in step 1, silicon wafer is single-sided polishing p-type lightly doped silicon wafer, and crystal orientation is (100), resistivity 10-15
Ω .cm, silicon wafer cut lengths are 20mm × 10mm.
5. its preparation side of the heterogeneous multilevel structure of silicon nanowires of netted tungsten oxide nano modification according to claim 3
Method, which is characterized in that in step 3, carry out spin coating 30-50s, flash baking 5-10min using sol evenning machine, repeat spin coating, dry
It is heat-treated after 4-6 times dry；The condition of heat treatment are as follows: heat treatment temperature is 640-660 DEG C, heat treatment time 1.5-
2.5h。
6. its preparation side of the heterogeneous multilevel structure of silicon nanowires of netted tungsten oxide nano modification according to claim 3
Method, which is characterized in that sodium tungstate dosage is 10-12 mass parts, and ammonium sulfate dosage is 9-10 mass parts, and each mass parts are
1g；In step 4, the sample with seed layer is down to 20-25 DEG C of room temperature, clearly in an oven after 170-190 DEG C of heat treatment 7-9h
After washing, 70-90 DEG C of dry 9-11h in an oven.
7. the gas sensor of the heterogeneous multilevel structure of silicon nanowires based on the modification of netted tungsten oxide nano, which is characterized in that will
The heterogeneous multilevel structure platinized electrode of silicon nanowires of netted tungsten oxide nano modification, by template in silicon nanowires/oxidation
It is 0.5-3cm that two spacing are formed on the compound heterogeneous multilevel structure of tungsten nanowires, and size is the electrode of 1-3mm*1-3mm, is formed
Ohmic contact between electrode and silicon chip surface nano wire, as sputtering target material, argon gas splashes the metal platinum of use as working gas
Time 1-4min is penetrated, forming thickness of electrode is 80-120nm.
8. the air-sensitive of the silicon nanowires heterogeneous multilevel structure according to claim 7 based on the modification of netted tungsten oxide nano
Element, which is characterized in that the quality purity of argon working gas is 99.999%, and the quality purity of target metal platinum is
99.95%, ontology vacuum 1.0 × 10-2Pa or less.
9. application of the heterogeneous multilevel structure of silicon nanowires of netted tungsten oxide nano modification in detection nitrogen dioxide, feature
It is, the detection for being directed to 1ppm concentration is realized under 20-25 degrees Celsius of room temperature, the response time, recovery time was average averaged less than 1s
For 100-160s.
10. the gas sensor of the heterogeneous multilevel structure of silicon nanowires based on the modification of netted tungsten oxide nano is in detection nitrogen dioxide
In application, the detection for being directed to 1ppm concentration is realized under 20-25 degrees Celsius of room temperature, the response time is averaged less than 1s, recovery time
Average out to 100-160s.
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