JPH11240722A - Complex semiconductor composition and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition having a nonlinear electric resistance value and excellent semiconductor characteristics, by sticking a specific amount of pulverized copper and/or copper oxide to semiconductor powder selected from Fe3 O4 , SnO2 and TiO2 to give a baked substance. SOLUTION: Fine particles of copper and/or copper oxide in an amount of 0.01-1 mol are stuck to 1 mol of semiconductor powder. The composition is obtained by dispersing pulverized copper and/or copper oxide into a polymer without aggregation to give a polymer complex, mixing the complex with semiconductor powder and baking the mixture. The polymer complex is obtained by preparing a polymer or oligomer film containing a functional group selected from cyanc, amino and thiol groups at the end or side chain of the molecule and depositing copper on the film so as to disperse copper as fine particles of copper and/or copper oxide (Cu2 O).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite semiconductor composition and a method for producing the same, and more particularly, to a gas sensor having improved non-linear resistance in voltage and current characteristics, increased sensitivity, and improved catalytic performance. The present invention relates to a composite semiconductor composition that can be used for a photocatalyst and the like and a method for producing the same.

[0002]

_2. Description of the Related Art Conventionally, Fe ₃ O ₄ , SnO ₂ , TiO ₂
Such a semiconductor powder alone does not have large non-linear resistance and is insufficient for use as a semiconductor. The non-linear resistance has a characteristic that the excited electrons increase with the increase of the electric field applied to the sample and the current increases, and is one of the indicators of the semiconductor performance.
Recently, a composition obtained by mixing a polymer composite in which fine particles of noble metal are dispersed in a polymer without agglomeration and a titanium compound having a liquid organic group with an organic solvent is applied to a substrate. After removing the organic solvent, a heat treatment is performed to produce a titanium oxide film (Patent No. 2714927).
No.) has also been proposed.

Also, gold is deposited on a polymer or oligomer film having at least one functional group selected from cyano groups, amino groups, and thiol groups at the terminal or / and side chains of the molecule. A polymer composite in which fine particles of gold are dispersed is prepared, and the composite is dissolved in a solvent or water to form a fine particle dispersion, and a carrier such as titanium oxide is charged therein. A method has been developed in which gold particles are fixed to titanium oxide or the like by baking at a decomposition temperature or higher. As described above, many attempts have been made to support gold fine particles on titanium oxide.

Further, Fe ₃ O ₄ , SnO ₂ , TiO ₂
An ion implantation method of implanting copper ions into a semiconductor such as described above has also been attempted.

[0005]

However, there have been many attempts to support fine particles on titanium oxide as in the prior art, but this method mainly supports fine particles of noble metal such as gold, and no copper-based method has been found. . This is Cu or Cu
_{This is because 2} O fine particles cannot be obtained stably. Also,
The ion implantation method is not practical because the equipment is large and the treatment amount is small, and it is not suitable for treating powder. The present invention is intended to solve such a problem, and has a structure in which fine particles are fixed at the grain boundaries of the semiconductor powder, and electrons are emitted from the semiconductor powder excited by an electric field or light to the fine particles at the grain boundaries. Provided is a composite semiconductor composition capable of significantly increasing the nonlinear resistance of a composite semiconductor by flowing the composite semiconductor composition, and a method for producing the same.

[0006]

That is, according to the first aspect of the present invention, there is provided finely divided copper and / or copper oxide and at least one selected from the group consisting of Fe ₃ O ₄ , SnO ₂ and TiO _2. And a fired body with the semiconductor powder of the above, and is a composite semiconductor composition in which 0.01 to 1 mol of fine particles of copper and / or copper oxide are fixed to 1 mol of the above semiconductor powder.

According to the invention of claim 2 of the present application, a polymer composite obtained by dispersing finely divided copper and / or copper oxide in a polymer without agglomeration is added to Fe ₃ O.
_At least one kind of semiconductor powder selected from the group consisting of SnO ₂ , SnO ₂ , and TiO ₂ is mixed and fired, whereby copper and / or copper oxide fine particles are added to 1 mole of the semiconductor powder. The present invention is directed to a method for producing a composite semiconductor composition in which 01 to 1 mol is fixed.

According to the invention described in claim 3 of the present application, claim 2
The polymer composite described above forms a polymer or oligomer film having at least one functional group selected from a cyano group, an amino group, and a thiol group at a terminal or a side chain of the molecule. The present invention relates to a method for producing a composite semiconductor composition which is obtained by depositing copper and dispersing it in a film as fine particles of copper and / or copper oxide.

According to the invention described in claim 4 of the present application, claim 2
After polymerizing a synthetic polyamide so that the polymer composite described in the above limits the molecular weight to the range of 400 to 7,000, a film obtained by dissolving the same in a solvent is formed on a substrate, and a copper film is formed on the film. And dispersing it as fine particles of copper and / or copper oxide in the film to obtain a composite semiconductor composition.

According to the invention of claim 5 of the present application, the synthetic polyamide polymerized so as to limit the molecular weight to the range of 400 to 7,000 is H ₂ N— (CH ₂ ) _n COOH (n is 1 to 36). An amino acid monomer represented by the following formula:
_{- (CH 2) m -NH 2} (m is 1 to 36, R is CH
_3- , a cyano group, an amino group, and a thiol group), an amine or polyamine having an amine group at the molecular terminal, and a cyano group, an amino group, and a thiol group on the side chain of the amine or polyamine. The present invention provides a method for producing a composite semiconductor composition obtained by polymerizing at least one polymerization inhibitor selected from amines or polyamines having at least one selected functional group in the presence of a catalyst.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer composite used here is:
A thermodynamically non-equilibrated polymer layer is prepared, and at least copper is adhered to the surface of the polymer layer, and then the polymer layer is heated to stabilize the polymer layer, whereby particles are formed from the copper. It is obtained by dispersing into fine particles of copper and / or copper oxide (Cu ₂ O) having a diameter of 100 nm or less, preferably 1 to 50 nm, without agglomeration in a polymer.

First, in obtaining the polymer composite, it is necessary to mold the polymer layer into a thermodynamically non-equilibrium state. Specifically, this is a vacuum deposition method in which a polymer is heated and melted in a vacuum to evaporate and solidify a polymer layer on a substrate, or a polymer is melted at a melting temperature or higher,
In this state, there is a melting and quenching solidification method in which the polymer layer is immediately poured into liquid nitrogen or the like, rapidly cooled, and a polymer layer is deposited on the substrate.

In the case of the vacuum deposition method, a vacuum degree of 10 ^-4 to 10 ^-6 Torr and a deposition rate of 0.1 to 100 μm / min, preferably 0.1 to 10 ^-6 Torr, using an ordinary vacuum deposition apparatus.
At 5 to 5 μm / min, a polymer layer can be obtained on a substrate such as glass. In the melting quenching and solidification method, a polymer is melted and cooled at a rate higher than the critical cooling rate inherent to the polymer to obtain a polymer layer. The polymer layer thus obtained is placed in a non-equilibrium state, which is thermodynamically unstable, and transitions to an equilibrium state over time.

The polymer used in the present invention includes, for example, nylon 6, nylon 66, nylon 11, nylon 12, nylon 69, polyethylene terephthalate (PET),
Polyvinyl alcohol, polyphenylene sulfide (P
PS), polystyrene (PS), polycarbonate, polymethyl methacrylate, etc., having a molecular aggregation energy of 2000 cal / mol or more are preferable. The polymer includes a crystalline polymer and an amorphous polymer which are generally referred to. The molecular cohesion energy is described in Chemical Chemistry Handbook, edited by The Chemical Society of Japan (issued in 1973)
On page 890.

Subsequently, the thermodynamically non-equilibrated polymer layer is transferred to a step of bringing copper into close contact with its surface.
In this step, copper is deposited on the polymer layer by a method such as vapor deposition of copper on the polymer layer by a vacuum deposition apparatus or by directly attaching a copper plate to the polymer layer.

The composite in which the copper and the polymer layer are in close contact with each other is
The polymer layer is heated to a temperature equal to or higher than the glass transition point of the polymer and equal to or lower than the flow temperature to shift the polymer layer to a stable state. As a result, the copper becomes fine particles of copper and / or copper oxide (Cu ₂ O) having a maximum particle size distribution in the range of 1 to 50 nm at 100 nm or less, and diffuses and penetrates into the polymer layer. Continues until the polymer layer is completely stabilized, and the copper layer adhering to the polymer layer also decreases in thickness and eventually disappears. The fine particles of copper and / or copper oxide (Cu ₂ O) are distributed in the polymer layer without aggregation. In this case, the content of the fine particles is 0.01 to 90% by weight,
This content can be adjusted by changing the conditions for forming the polymer layer or changing the thickness of the copper film.

In the present invention, the method for producing the polymer composite is not limited to the above-mentioned method, but may be, for example, a gas phase method belonging to a melt vaporization method, a liquid phase method belonging to a precipitation method, a solid phase method, or a copper dispersion method. Or / and producing fine particles of copper oxide (Cu ₂ O),
A method of mechanically mixing the fine particles with a polymer consisting of a solution or a melt, or a method of simultaneously evaporating the polymer and copper and / or copper oxide (Cu ₂ O) and mixing them in a gas phase. is there.

The method for producing the polymer composite of the present invention includes a polymer or an oligomer having at least one functional group selected from a cyano group, an amino group and a thiol group at the terminal or side chain of the molecule. A membrane of
Copper can be deposited on this film and dispersed in the film as fine particles of copper and / or copper oxide (Cu ₂ O).

The above-mentioned polymer or oligomer has a cyano group (-CN) or an amino group (-
NH ₂ ) and at least one functional group selected from thiol groups (—SH), and the backbone of which is polyethylene oxide, polyethylene glycol, polyvinyl alcohol, nylon 11, nylon 6, nylon 66, nylon 6 10. Polyethylene terephthalate, polystyrene, etc., whose melting point or softening point is 40 to 100 ° C. The average molecular weight of the oligomer is not particularly limited, but is about 500 to 3,000. The functional group particularly easily forms a covalent bond or a coordination bond with copper and / or copper oxide (Cu ₂ O) on the surface of the fine particles, suppresses grain growth, and enhances the dispersibility of the fine particles.

As a method of producing the film 2 other than the above, a synthetic polyamide is polymerized so that the molecular weight is limited to a range of 400 to 7,000, and then a solution obtained by dissolving the same in a solvent is formed on a substrate. You can also. In this case, if the molecular weight is less than 400, the synthetic polyamide is likely to evaporate during deposition of the metal or metal oxide under reduced pressure,
On the other hand, when it exceeds 7,000, dispersion of the fine particles hardly occurs.

The molecular weight was measured using a gel permeation chromatograph (manufactured by Shimadzu Corporation).
Using a mobile phase of chloroform or chloroform and meta-cresol in a weight ratio of 4: 1, the synthetic polyamide obtained by gel permeation chromatography was separated and analyzed, and the retention time of polystyrene with a known molecular weight and commercially available as standard data was measured. Was determined to determine the molecular weight of the synthetic polyamide.

Specifically, as a method for producing the above-mentioned synthetic polyamide, H ₂ N— (CH ₂ ) _n COOH (where n is 1 to 5)
36) an amino acid monomer represented by the molecular formula:
(CH ₂ ) _m —NH ₂ (m is 1 to 36, R is CH ₃ —,
An amine or a polyamine having an amine group at the molecular end represented by a cyano group, an amino group, and a thiol group), and a functional group selected from a cyano group, an amino group, and a thiol group in a side chain of the amine or the polyamine. At least one polymerization inhibitor selected from amines or polyamines having at least one group,
A catalyst or the like is charged with a solvent such as N-methylpyrrolidine or dimethylacetamide, and stirred at 100 to 150 °.
C, and the mixture is polymerized while flowing nitrogen gas. After completion of the polymerization, the mixture is cooled to room temperature. The reaction product is ethyl acetate,
The mixture was poured into toluene, hexane, etc., allowed to stand for 24 hours to precipitate, and the precipitate was collected by filtration, washed,
Dried at 0-70 ° C.

As the amino acid monomer represented by the molecular formula of H ₂ N— (CH ₂ ) _n COOH (n is 1 to 36), 11-aminoundecanoic acid, 9
-Aminononanoic acid.

As the polymerization inhibitor, R- (CH ₂ )
_m -NH ₂ (m is 1 to 36, R is CH ₃ -, cyano group,
An amine or a polyamine having an amine group at the molecular terminal represented by an amino group or a thiol group), and at least a functional group selected from a cyano group, an amino group, and a thiol group in a side chain of the amine or the polyamine. It is selected from amines or polyamines having one or more, specifically, hexamethylenediamine, ε-aminocapronitrile, ethylenediamine and the like are used.

As the catalyst, quinoline, triphenyl phosphite or the like is used.

The semiconductor powder used in the present invention is Fe powder.
It is at least one selected from ₃ O ₄ , SnO ₂ , and TiO ₂ and has a powder diameter of 0.1 to 10 μm.

In the present invention, the obtained polymer composite is mixed with a high boiling organic solvent such as dimethylimidazolidinone, metacresol, dimethylformamide, carbitol, terpinol, diacetone alcohol, triethylene glycol, para-xylene and the like. After dissolving into a paste,
The semiconductor powder is uniformly dispersed therein and dried to form a dry powder. Further, the polymer composite and the semiconductor powder are mixed, dissolved in an organic solvent to form a paste, and then dried to form a dry powder. The dried powder is put into a mold, pre-formed by pressing, and baked at 500 to 900 ° C. or higher for 15 to 60 minutes in air, nitrogen atmosphere, or reduced pressure to obtain a desired composite semiconductor composition. be able to. Of course, it is not necessary to preform, and the dried powder can be directly fired.

In the fired composite semiconductor composition of the present invention, the semiconductor powder [A] usually shows a slight non-linear electric resistance, but fine particles of copper and / or copper oxide [B] are fixed at the grain boundaries. By doing so, the composite semiconductor composition [AB
_x ], the electrons excited by the electric field flow into the fine particles through the grain boundaries, and exhibit extremely large non-linear electric resistance. In this case, the mixing ratio of the semiconductor powder [A] and the copper or / and copper oxide fine particles [B] is such that [A] is 1 mol and [B] is in the range of 0.01 to 1 mol. , [B]
Is less than 0.01 mole, the excited electrons flow and the number of fine particles into which electrons flow is reduced, so that the semiconductor characteristics are not exhibited. As a phase, the effect of flowing electrons is lost, and semiconductor characteristics are not exhibited.

[0029]

Next, the present invention will be described in more detail with reference to specific examples. Examples 1 to 5 and Comparative Examples 1 to 5 (Preparation of Polymer Composite) Using a vacuum deposition apparatus, 5 g of nylon 11 polymer pellets were placed in a tungsten board, and the pressure was reduced to 10 ^-6 Torr. Then, a voltage is applied to heat the tungsten board in a vacuum to melt the polymer, and the substrate (glass plate) placed on the mounting table is placed on a substrate (glass plate) at a degree of vacuum of 10 ^-4 to 10 ^-6 Torr at about 1 μm.
A polymer layer of a deposited film having a thickness of about 5 μm was obtained at a rate of / min.
The molecular weight of this polymer layer is １ ／ of that of the polymer pellet.
It is about 1/10.

Further, a copper chip was placed in a tungsten board, heated and melted, and vapor-deposited at a degree of vacuum of ^{10.sup.- 4} to ^10.sup.-6 Torr to deposit a vapor-deposited copper film on the polymer layer.
This was taken out of the vacuum evaporation apparatus and left in a thermostat kept at 120 ° C. for 10 minutes to obtain a composite. As a result, the polymer composite contained 33% by weight of a layer, and the average particle size was 5 nm. The obtained polymer composite and meta-cresol were mixed at a weight ratio of 1: 1 to prepare a polymer composite solution.

(Preparation of Composite Semiconductor Composition [AB _x ]) Next, a predetermined amount of the semiconductor powder [A] is mixed with a predetermined amount of the polymer composite solution, and the mixture is depressurized at 70 ° C. For 2 days. A predetermined amount of the dried mixed powder was placed in a disk-shaped mold and pressed by a press molding machine to produce a disk-shaped preform having a thickness of 1 mm. This preform is 600 °
C. Baking for 30 minutes under reduced pressure. The size of the fired sample was 12 mm in diameter and 1 mm in thickness. Table 1 shows the composition of the composite semiconductor composition.

Further, the electric resistance characteristics of the obtained fired sample were evaluated and the non-linear electric resistance value was obtained. Table 1 shows the results. The method for evaluating the electric resistance characteristics and the method for evaluating the non-linear electric resistance are as follows.

In the method for evaluating the electric resistance characteristics, silver paste was applied to both upper and lower surfaces of a disk-shaped sample to form electrodes, and lead wires were attached. Voltage was applied to the two lead wires stepwise (at 2 V intervals) using a potentiostat, and the current value at that time was measured. The maximum voltage was 20V.

The method of determining the non-linear electric resistance value is based on the obtained current-voltage characteristic, which is obtained when the current and the voltage are directly proportional.
Assuming that the current at the time of applying V is 1, the current at 20 V of each sample is shown as a ratio. Therefore, this value (non-linear electric resistance value)
Is larger, the greater the non-linearity,
Conversely, if it is close to 1, it will be referred to as linear electric resistance (ohmic).

[0035]

[Table 1]

As a result, the composite semiconductor composition of the example
It can be seen that the non-linear electric resistance value is large and shows excellent semiconductor characteristics.

Example 6 (Preparation of polymer composite) A 20% by weight solution was prepared by dissolving polyethylene oxide having an average molecular weight of 2,000 (determined by GCP) in which the terminal of the molecule was diaminated in acetone in acetone. When this solution was applied to glass as a substrate and dried, a coating film of polyethylene oxide having a thickness of several microns was obtained.

The coating film held on the glass was placed in a vacuum deposition apparatus in which a vessel having an electron beam evaporation source was heated to 60 ° C. in advance and adjusted to a degree of vacuum of about 5 × 10 ^-5 . Copper in a crucible installed in a vacuum evaporation apparatus was heated using an electron beam and evaporated. The evaporated copper was deposited on the polyethylene oxide coating. 30 on the crystal unit
The amount of copper evaporated was adjusted to a thickness of nm.

The inside of the vacuum evaporation apparatus was returned to the atmospheric pressure, and the polyethylene oxide held on the glass was taken out. Copper deposited on the polyethylene oxide is chemically bonded to amino groups of the polyethylene oxide at the same time as the
m, and the coating film was yellow-green.
In addition, in order to make the dispersion of the copper oxide fine particles uniform, heating was performed at 60 ° C. in a nitrogen stream.

When the polyethylene oxide in which the copper oxide fine particles are dispersed is peeled off from the glass and immersed in water,
As a result, an aqueous dispersion of copper oxide fine particles having a yellowish green color was obtained. This aqueous solution was stable, and the yellow-green color did not disappear even after one month of standing.

The resulting polymer composite and meta-cresol were mixed at a weight ratio of 1: 1 to prepare a polymer composite solution.

(Preparation of Composite Semiconductor Composition [AB _x ]) Next, 1 mol of the powder semiconductor Fe ₃ O ₄ was mixed with 0.1 mol of the copper oxide fine particles in the polymer composite solution. The mixture was dried at 70 ° C. under reduced pressure for 2 days. A predetermined amount of the dried mixed powder was placed in a disk-shaped mold and pressed by a press molding machine to produce a disk-shaped preform having a thickness of 1 mm. The preform was fired at 600 ° C. under reduced pressure for 30 minutes. The size of the fired sample is 12mm in diameter and 1mm in thickness
Met. Table 1 shows the composition of the composite semiconductor composition.

Further, the electrical resistance characteristics of the obtained fired sample were evaluated and the non-linear electrical resistance value was determined. Table 2 shows the results.

[0044]

[Table 2]

As a result, the composite semiconductor composition of the example
It can be seen that the non-linear electric resistance value is large and shows excellent semiconductor characteristics.

[0046]

As described above, according to the first aspect of the present invention, finely divided copper and / or copper oxide and Fe ₃
A fired body of at least one kind of semiconductor powder selected from O ₄ , SnO ₂ and TiO ₂ , wherein copper and / or copper oxide fine particles are present in an amount of 0.01 to 1 with respect to 1 mol of the semiconductor powder. In the composite semiconductor composition to which the moles are fixed,
The effect is that the nonlinear electric resistance value is large and excellent semiconductor characteristics are exhibited.

Further, in the invention according to claims 2 to 5, the present invention
A polymer composite obtained by dispersing finely divided copper and / or copper oxide in a polymer without agglomeration, and at least one semiconductor selected from Fe ₃ O ₄ , SnO ₂ , and TiO ₂ By mixing and baking the powder, copper or / and / or 1 mole of the semiconductor powder is mixed.
The method for producing a composite semiconductor composition to which 0.01 to 1 mol of copper oxide fine particles are fixed has an effect of exhibiting a large nonlinear electric resistance value and excellent semiconductor characteristics.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C01G 19/00 C08K 3/08 23/00 3/22 C08K 3/08 C08L 101/00 3/22 B01J 23/74 301M C08L 101 / 00 23/82 M

Claims (5)

[Claims] 1. A fired body of finely divided copper and / or copper oxide and at least one semiconductor powder selected from Fe ₃ O ₄ , SnO ₂ and TiO ₂ , wherein said semiconductor powder 1 A composite semiconductor composition comprising 0.01 to 1 mol of fine particles of copper and / or copper oxide fixed to mol. 2. A polymer composite obtained by dispersing finely divided copper and / or copper oxide in a polymer without agglomeration, and Fe ₃ O ₄ , SnO ₂ , and TiO ₂
At least one kind of semiconductor powder selected from the above is mixed and baked to fix 0.01 to 1 mole of copper or / and copper oxide fine particles per mole of the semiconductor powder. A method for producing a composite semiconductor composition, comprising: 3. The polymer composite according to claim 2, wherein the polymer or oligomer has at least one functional group selected from a cyano group, an amino group, and a thiol group at a terminal or a side chain of the molecule. And producing a composite semiconductor composition obtained by dispersing copper as fine particles of copper and / or copper oxide in the film by depositing copper on the film. 4. The polymer composite according to claim 2, wherein a synthetic polyamide is polymerized so that the molecular weight is limited to a range of 400 to 7,000, and then the resultant is dissolved in a solvent to form a film on a substrate. Then, a method for producing a composite semiconductor composition obtained by depositing copper on the film and dispersing it as fine particles of copper and / or copper oxide in the film. 5. A synthetic polyamide polymerized so as to limit the molecular weight to the range of 400 to 7,000 is H ₂ N- (C
An amino acid monomer represented by a molecular formula of H ₂ ) _n COOH (n is 1 to 36); and R— (CH ₂ ) _m —NH ₂ (m is 1 to 36, R is CH ₃ —, a cyano group, an amino group, And an amine or polyamine having an amine group at the molecular terminal represented by thiol group), and at least one functional group selected from a cyano group, an amino group, and a thiol group on the side chain of the amine or polyamine. 5. The method for producing a composite semiconductor composition according to claim 4, wherein the composite semiconductor composition is obtained by polymerizing at least one polymerization inhibitor selected from amines or polyamines in the presence of a catalyst.