JP4706047B2 - Substrate suitable for device containing organic material, method for producing the same, and device containing organic material using the same - Google Patents

Description

  The present invention relates to a substrate suitable for an organic material-containing device and a manufacturing method thereof, and further relates to an organic material-containing device using the substrate.

  As represented by organic EL elements, devices in which inorganic or semiconductor materials in conventional devices are replaced with organic materials have been put into practical use. In recent years, a molecular device that realizes a fine structure by organizing organic molecules (including biomolecules) has attracted attention. In these organic material-containing devices, a semiconductor substrate may be used as a substrate for supporting the organic material. When a semiconductor substrate is used, the function of the organic material can be controlled by an element formed on the surface of the semiconductor substrate. In order to maintain the device characteristics stably for a long period of time, it is desired to fix the organic material by chemically bonding it to the surface of the substrate.

  The organic material can be bonded to the semiconductor substrate using, for example, a silane coupling agent. The silane coupling agent reacts with a hydroxyl group present on the surface of an oxide film on the semiconductor substrate (for example, a silicon oxide film formed on a silicon substrate), and as a result of this reaction, an organic material is fixed on the surface of the semiconductor substrate. .

  However, when an insulating oxide film is present on the semiconductor substrate, electrical connection between the semiconductor substrate and the organic material becomes difficult. For example, when an organic EL element is formed on a silicon substrate, the presence of a silicon oxide film hinders charge injection into the organic material. Further, in the method using a silane coupling agent, it is necessary to modify the organic material with a hydrolyzable functional group such as a silyl halide group. However, depending on the chemical stability of the organic material, such modification may not be possible. Sometimes it is not possible.

A method of increasing the reactivity of the substrate surface by heating the semiconductor substrate in an ultrahigh vacuum of about 10 ⁻¹⁰ Torr is also known. By heating in an ultrahigh vacuum, dangling bonds of semiconductor atoms and dimer bonds (for example, Si = Si bonds) of semiconductor atoms are generated on the surface of the semiconductor substrate. When an organic material having an unsaturated bond on this surface is reacted, the organic material is directly bonded to the semiconductor substrate. A semiconductor substrate in which halogen atoms are bonded to the surface to increase the surface reactivity is also known. If the halogen atom is replaced with an organic material, the organic material can be directly bonded to the surface of the semiconductor substrate.

  However, a semiconductor substrate whose surface reactivity has been increased by introducing dangling bonds or halogen atoms has a very high reactivity with moisture and cannot be handled in the atmosphere. For this reason, the preservation | save of a board | substrate, a conveyance process, and also the process of carry | supporting an organic material also receive restrictions. In order to fix the organic material on the surface of the substrate with increased reactivity, for example, the organic material may be deposited under a reduced pressure atmosphere. However, the organic material loses its function when heated under reduced pressure like a biomolecule. There are also materials.

  Thus, at present, a substrate that is suitable for construction of an organic material-containing device that uses the function of an organic material and that is easy to handle has not been obtained.

Non-patent document 1 explains in detail the surface of the semiconductor substrate and the fixation of organic molecules on the surface.
Jillian Buriak, “Organic Metal Chemistry on Silicon and Germanium Surfaces”, Chemical Reviews, American Chemical Society, USA, May 2002, 102, 5, pp. 1272-1308

  In view of the above circumstances, an object of the present invention is to provide a substrate that is suitable for an organic material-containing device and that is easy to handle. Another object of the present invention is to provide a new organic material-containing device using this substrate.

The present invention provides a substrate having a Si (111) (1 × 1) plane in which hydrogen atoms and amino groups are chemisorbed and terminated by the hydrogen atoms and amino groups .

  From another aspect, the present invention is chemically adsorbed on a semiconductor surface of an organic material-containing device including the substrate of the present invention and an organic material disposed on the semiconductor surface of the substrate, and further on the semiconductor surface of the substrate of the present invention. Provided is an organic material-containing device in which an amino group and an organic molecule are reacted and the organic molecule is fixed to the semiconductor surface.

  An amino group is a group capable of chemically reacting with many functional groups and has excellent affinity with biomolecules. For this reason, the substrate of the present invention is suitable for fixing a wide range of organic materials including biomolecules.

  The amino group, unlike the dangling bonds, is stable in the air at normal temperature and normal pressure. For this reason, the board | substrate of this invention can be handled in air | atmosphere, and there are few restrictions in the process of the preservation | save and conveyance process, and also the process of fixing an organic material.

  In the substrate of the present invention, those chemically adsorbed on the semiconductor surface together with amino groups are hydrogen atoms having poor reactivity with organic molecules and moisture in the atmosphere. By chemically adsorbing hydrogen atoms together with the amino group, the handleability of the substrate is improved, and the introduced organic molecule is likely to react selectively with the amino group.

  In the substrate of the present invention, since the amino group is chemically adsorbed on the semiconductor surface, the amino group is stably held. Further, when the organic molecule is immobilized by reacting with an amino group, the organic molecule and the semiconductor surface are chemically bonded together. For this reason, the organic molecule is firmly fixed on the semiconductor surface, and at the same time, the electrical connection between the organic molecule and the semiconductor surface can be easily secured.

  As described above, the present invention provides a highly versatile substrate that is suitable for an organic material-containing device and is easy to handle.

In the present invention, hydrogen atoms and amino groups are chemically adsorbed on the Si (111) (1 × 1) surface which is the semiconductor surface. Hydrogen atoms and amino groups are bonded to Si atoms constituting the semiconductor surface .

In the Si (111) plane, the bond from Si extends perpendicular to the surface. This bond is suitable for fixing an organic material, and is convenient for the construction of a molecular device in which organic molecules should be arranged precisely and precisely. The most preferred semiconductor surface for the construction of molecular devices is the Si (111) (1 × 1) plane. If a method described later is used, an amino group can be introduced into the Si (111) (1 × 1) plane.

  In order to configure the Si (111) surface as the semiconductor surface, a Si (111) substrate may be used. However, the substrate is not limited to this, and a Si single crystal substrate having another plane orientation may be used, a Si polycrystalline substrate may be used, and a Ge substrate or a compound semiconductor substrate may be used. Further, instead of a so-called bulk substrate, for example, an SOI (Silicon on Insulator) substrate may be used. Alternatively, the surface of a semiconductor film formed on an insulating film such as an oxide film formed on a bulk substrate may be a semiconductor surface. In the case of forming a semiconductor film, a non-semiconductor such as glass, ceramics, resin, or metal may be used as a substrate on which the film is formed. In the practice of the present invention, it suffices if there is a semiconductor surface on which amino groups can be chemically adsorbed, and the substructure on the semiconductor surface is not limited.

  An element such as a MOSFET may be appropriately formed on the semiconductor surface by a conventionally known technique.

  The amino group is fixed by a chemical bond with an atom contained in the semiconductor surface. For example, when the semiconductor surface is composed of atoms containing Si, the amino group is fixed to the surface by Si—N bonds.

The semiconductor surface of the present invention is terminated with hydrogen atoms and amino groups . This semiconductor surface is substantially free of chemical species other than hydrogen atoms and amino groups, such as halogen atoms and hydroxyl groups. When an amino group is introduced into a semiconductor surface terminated with hydrogen by a method described later, this surface becomes a semiconductor surface terminated with a hydrogen atom and an amino group.

  FIG. 1 illustrates a bonding state of a silicon surface on which hydrogen atoms and amino groups are chemisorbed. Here, a Si (111) surface on which a primary amino group and a hydrogen atom are adsorbed is shown. However, as described above, the semiconductor surface is not limited to this, and the amino group is not limited to the primary amino group but may be a secondary amino group or a tertiary amino group.

  Amino groups react with many functional groups such as aldehyde groups, carboxyl groups, carbonyl chloride groups, carbonyl groups. By utilizing this, various organic materials can be fixed on the semiconductor surface, so that various devices using organic materials can be constructed.

For example, when a primary amino group (—NH ₂ ) and an organic molecule (CHO—R) having an aldehyde group are reacted, the organic molecule is fixed through an azomethine bond (—N═CH—R). . FIG. 2 shows a reaction between an amino group chemisorbed on the silicon surface and terephthalaldehyde as an example of this reaction.

  The organic molecule can be fixed not only by azomethine bonds but also through various bonds. For example, a peptide bond (acid amide bond) can be formed by reacting a primary amino group with an organic molecule having a carbonyl chloride group. FIG. 3 shows a reaction between an amino group chemisorbed on the silicon surface and benzoyl chloride as an example of this reaction.

  For fixing the organic molecule, it is preferable that the organic molecule contained in the organic molecule is bonded to the amino group. Specifically, the carbon atom contained in the organic molecule is bonded to the nitrogen atom contained in the amino group. C—N may be formed, and a carbon atom and a nitrogen atom more preferably form a double bond C═N. This is because π electrons in a carbon-nitrogen double bond existing in an azomethine bond or the like contribute to the transfer of electrons between the semiconductor surface and an organic molecule.

  An organic molecule containing (—CH═N—) may be used as the organic molecule bonded to the amino group. Examples of such organic molecules include conductive organic molecules containing the following repeating unit (1).

(1) —R ¹ —CH═N—R ² —N═CH—
Here, R ¹ and R ² are each independently a group having a π-electron conjugated chain having a main chain length in the range of 0.65 nm to 4.0 nm as a main chain.

  A manufacturing method and a specific example of the organic material-containing device using the conductive organic molecule will be described later.

  The substrate of the present invention can be applied to a wide range of devices using an organic material. The substrate of the present invention is suitable for devices using biomolecules such as biochips, DNA chips, and DNA sensors in addition to various devices in the electronics field such as organic EL elements, organic solar cells, and organic sensors. Since amino groups are excellent in affinity with biomolecules, it is possible to immobilize biomolecules such as DNA and proteins on the semiconductor surface of the substrate of the present invention at normal temperature and normal pressure. The present invention includes various organic material-containing devices exemplified above.

  In the organic material-containing device of the present invention, it is only necessary that the organic material is disposed on the semiconductor surface, and a chemical bond (nitrogen-carbon bond in the above example) between the amino group and the organic molecule is not essential. . For example, the crystal structure of pentacene, which is known as an organic material for organic TFT elements, has a close relationship with charge mobility and is affected by the interaction with the substrate. Therefore, the charge mobility of pentacene can be controlled through the crystal structure by controlling the surface free energy of the semiconductor surface by introducing amino groups. An organic material-containing device may be constructed using an organic material that is not chemically bonded to an amino group, such as pentacene.

In the method of the present invention, an amino group containing a nitrogen atom derived from a nitrogen-containing reactive species is chemisorbed on the semiconductor surface by bringing a nitrogen-containing reactive species into contact with the semiconductor surface on which hydrogen atoms are chemisorbed. The supply of the nitrogen-containing reactive species to the semiconductor surface is preferably performed from the gas phase, and the nitrogen-containing reactive species are suitably ammonia or radicals generated from ammonia. When the nitrogen-containing reactive species is ammonia, the semiconductor surface is preferably irradiated with electromagnetic waves in an atmosphere containing ammonia. Examples of radicals include NH ₂ radicals generated by thermally decomposing ammonia.

When the semiconductor surface is heated under reduced pressure (for example, about 10 ⁻¹⁰ Torr), dangling bonds increase on the semiconductor surface. This dangling bond functions as a reaction point for introducing the nitrogen-containing reactive species. However, in this method, the structure of the semiconductor surface is disturbed, and a desired semiconductor surface may not be obtained. For example, it is known that when a Si (111) surface is heated as described above, this surface is disturbed into a structure called 7 × 7 reconstruction.

In the case where such reconfiguration of the semiconductor surface is to be prevented, the substrate is heated to 450 ° C. or lower, for example, 0 to 100 ° C., in an atmosphere of 1 × 10 ⁻⁵ Pa or more, for example, 1 × 10 ^{−3 to} 1000 Pa. The nitrogen-containing reactive species may be brought into contact with the semiconductor surface while being held. By this method, for example, an amino group can be chemically adsorbed on this surface while maintaining the Si (111) (1 × 1) surface.

  Terminate with hydrogen while planarizing the surface to the atomic level by wet etching (eg, by treating the Si (111) surface with hydrofluoric acid and aqueous ammonium sulfite) by treating the semiconductor surface with a predetermined solution (etchant). can do. When the Si (111) plane is processed with the above-described etchant, a Si (111) (1 × 1) plane can be obtained.

  Since the irregularity of the surface causes variations in characteristics, a semiconductor surface that has been planarized to a high level is preferable for the function of the organic material. For example, in an organic sensor using an organic material, a weak signal can be detected more accurately by flattening a semiconductor surface. The planarized semiconductor surface is also suitable for molecular devices whose microstructure should be controlled.

  Depending on the use of the substrate, it may be desirable for the surface area of the semiconductor surface to be large. In this case, it is preferable to subject the semiconductor surface to a porous treatment such as anodization instead of a planarization treatment.

  The nitrogen-containing reactive species may be appropriately selected from nitrogen-containing molecules, radicals, and ions, but ammonia or radicals generated from ammonia are suitable. The nitrogen-containing reactive species may be brought into contact with the semiconductor surface in the liquid phase, but may be brought into contact in the gas phase. The gas phase may be normal pressure, but may be reduced in pressure.

  Many methods are conceivable for chemically adsorbing amino groups on the surface of a semiconductor that has been previously hydrogen-terminated. However, the following method can be used simply.

  By irradiating an electromagnetic wave in an atmosphere containing ammonia on a semiconductor surface in which hydrogen atoms have been chemically adsorbed in advance, an amino group can be introduced on this surface. As electromagnetic waves, ultraviolet rays, particularly ultraviolet rays having a wavelength of about 270 to 400 nm are suitable.

Even if NH ₂ radicals are generated by thermally decomposing ammonia in the vicinity of the semiconductor surface while exposing the semiconductor surface in which hydrogen atoms are chemically adsorbed in advance to an atmosphere containing ammonia, an amino group can be introduced into this surface. The decomposition of ammonia may be performed by energizing a tungsten filament, for example.

  The chemical adsorption of amino groups is not limited to the above, and for example, plasma may be used for generating radicals.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, the following Example is only the illustration of preferable embodiment of this invention similarly to the said description in this column.

Example 1
After the surface of the Si (111) substrate, that is, the silicon surface with the (111) plane orientation, was contacted with 5% hydrofluoric acid (hydrofluoric acid) for 5 minutes to perform hydrogen termination treatment, 50 mM ammonium sulfite The Si (111) surface flattened to the atomic level was obtained by contacting with an aqueous solution.

  Subsequently, the treated Si substrate was placed in the chamber, and the ammonia gas flow rate was maintained at 50 sccm and the atmospheric pressure was maintained at 2 torr (about 266 Pa). The temperature of the Si substrate was kept at 25 ° C. In this state, the hydrogen-terminated surface was irradiated with ultraviolet rays from a high pressure mercury lamp (100 W) through a sapphire window for 24 hours to introduce amino groups into the Si (111) surface.

  The Si (111) surface thus obtained was analyzed by XPS method (X-ray photoelectron spectroscopy) and FT-IR RAS method (Fourier transform infrared spectroscopic high sensitivity reflection method). The spectrum obtained by the former is shown in FIG. 4, and the spectrum obtained by the latter is shown in FIG.

(Comparative Example 1)
A (111) plane of the Si substrate was obtained in the same manner as in Example 1 except that the irradiation of ultraviolet rays from the high pressure mercury lamp was omitted. The results analyzed in the same manner as in Example 1 are shown in FIGS.

  In the XPS spectrum (FIG. 4), a peak due to nitrogen was observed in the vicinity of 398 eV from the silicon surface obtained in Example 1, but this peak was not observed from the silicon surface obtained in Comparative Example 1.

In FT-IR spectrum (FIG. 5), from the silicon surface obtained in Example 1, N-H stretching vibration and N-H absorption by deformation vibration is near 3350 cm ^-1, respectively, was observed in the vicinity of 1540 cm ^-1 These absorption peaks were not observed from the silicon surface obtained in Comparative Example 1. Further, in the FT-IR spectrum, absorption due to Si—H stretching vibration was observed from the silicon surface obtained in Comparative Example 1, but this peak was confirmed from the silicon surface obtained in Example 1. It was greatly attenuated. The XPS spectrum and the FT-IR spectrum showed that the silicon surface obtained in Example 1 was terminated with a hydrogen atom and an amino group.

In Example 1, the Si (111) surface after hydrogen termination and before introduction of amino groups was measured with an atomic force microscope (AFM), and as a result, a periodic step-and-terrace structure was observed. It was confirmed to be flat. Similarly, in Example 1, as a result of measuring the Si (111) plane after introduction of the amino group by AFM, a periodic step-and-terrace structure is also observed, and the flatness at the atomic level of this surface is maintained. It was confirmed that As shown in FIG. 5, a peak attributed to Si—H stretching appears at 2083 cm ⁻¹ in the FT-IR spectrum after hydrogen termination. This indicates that the Si (111) surface after hydrogen termination has a 1 × 1 structure in which hydrogen atoms are vertically bonded to the Si substrate surface. Judging from the measurement results of AFM, it was confirmed in Example 1 that the Si (111) (1 × 1) plane was maintained even after the introduction of the amino group.

(Example 2)
In Example 2, an amino group was introduced into the Si (111) plane in the same manner as in Example 1 except for the amino group introduction method. In Example 2, ultraviolet irradiation from a high-pressure mercury lamp is not performed, and a tungsten filament installed in the chamber is heated to 1000 ° C. by energization, and ammonia radicals generated by thermally decomposing ammonia gas on the filament are converted into Si radicals. (111) surface was supplied. The ammonia gas flow rate, atmospheric pressure, and Si substrate temperature were the same as in Example 1.

  The Si (111) surface thus obtained was analyzed by XPS method and FT-IR RAS method. The spectrum obtained by the former is shown in FIG. 6, and the spectrum obtained by the latter is shown in FIG.

In the XPS spectrum (FIG. 6), a peak due to nitrogen is observed in the vicinity of 398 eV, and in the FT-IR spectrum (FIG. 7), absorption due to N—H stretching vibration and N—H bending vibration is around 3350 cm ^−1, respectively. , Around 1540 cm ⁻¹ . Although absorption due to Si—H stretching vibration was confirmed, it was greatly attenuated as compared to before amino group introduction.

  From the above, it was confirmed that the silicon surface obtained in Example 2 was terminated with a hydrogen atom and an amino group. Further, the silicon surface obtained in Example 2 was also confirmed to maintain the Si (111) (1 × 1) plane even after the introduction of the amino group by the same measurement as in Example 1.

( Reference Example 1 )
A p-type Si substrate (resistivity: 24-360 Ωcm) was ultrasonically cleaned in ultrapure water for 10 minutes. Next, the substrate was immersed in a 1: 1 mixture of concentrated sulfuric acid and hydrogen peroxide solution for 10 minutes, and then washed in running water for 10 minutes. Further, this substrate was immersed in a 5% hydrofluoric acid aqueous solution for 5 minutes. Subsequently, the substrate was anodized in a solution prepared by mixing 46% hydrofluoric acid: 99% ethanol: ultrapure water at a ratio of 1: 1: 2. Anodization was performed for 750 seconds under the condition of a current density of ² mA / cm ² using a platinum electrode as the cathode. Thus, an Si substrate having a porous surface was obtained.

  In the same manner as in Example 1, the surface of the Si substrate was irradiated with ultraviolet rays from a high-pressure mercury lamp in an ammonia-containing atmosphere.

The silicon surface thus obtained was analyzed in the same manner as in Example 1. From the FT-IR spectrum, the absorption due to NH stretching vibration and NH deformation vibration was about 3350 cm ^−1, respectively, as in Example ^1. 1540 cm ⁻¹ , and absorption due to Si—H stretching vibration was also confirmed. From the above, it was confirmed that the silicon surface obtained in Reference Example 1 was also terminated with a hydrogen atom and an amino group.

(Comparative Example 2)
A porous Si substrate surface was obtained in the same manner as in Example 2 except that the irradiation of ultraviolet rays from the high-pressure mercury lamp was omitted.

  The silicon surface thus obtained was analyzed in the same manner as in Example 1. As in Comparative Example 1, no absorption due to the N—H bond was observed.

( Reference Example 2 )
The Si substrate obtained in Reference Example 1 was immersed in a dry toluene solution containing 10 mM bazoyl chloride and allowed to react at room temperature for 12 hours. After the reaction, benzoyl chloride physically adsorbed on the surface of the substrate was removed using a Soxhlet extractor (extraction solvent: toluene).

The surface of the Si substrate thus obtained was analyzed by the FT-IR method. As a result, a new absorption by C = O stretching vibration of aromatic ketone in the vicinity of 1700 cm ^-1 is a new absorption by plane skeleton vibration of the benzene ring in the vicinity of 1600 cm ^-1 was confirmed, respectively.

From the above, it was confirmed that the bezoyl chloride was fixed to the surface of the Si substrate obtained in Reference Example 2 by the amino group as shown in the reaction shown in FIG.

(Example 3 )
The Si substrate obtained in Example 1 was immersed in a dry toluene solution containing 10 mM terephthalaldehyde and allowed to react at room temperature for 12 hours. After the reaction, terephthalaldehyde physically adsorbed on the surface of the substrate was removed using a Soxhlet extractor (extraction solvent: toluene).

The (111) plane of the Si substrate thus obtained was analyzed by the FT-IR method. As a result, a new absorption by C = O stretching vibration of aromatic ketone in the vicinity of 1697cm ^-1 is a new absorption by plane skeleton vibration of the benzene ring in the vicinity of 1600 cm ^-1 was confirmed, respectively.

From the above, it was confirmed that terephthalaldehyde was fixed to the surface of the Si substrate obtained in Example 3 by amino groups as shown in the reaction shown in FIG.

[Form in which conductive organic molecules are bonded]
Hereinafter, a mode in which conductive organic molecules having the repeating unit shown in the above (1) are bonded to the semiconductor surface of the substrate according to the present invention will be described. According to this embodiment, conductive organic molecules having high linearity can be obtained, and in particular, conductive organic molecules bonded to the substrate in an upright state with respect to the substrate can be obtained. By changing the type of the π-electron conjugated chain of the monomer to be reacted, it is possible to obtain conductive organic molecules having various characteristics. By using such conductive organic molecules, an electronic device having high characteristics, such as an organic light emitting diode, can be realized. Furthermore, a quantum structure is formed in a single molecule and precise electronic state control is performed to realize a single molecule light emitting diode or the like.

The conductive organic molecule includes a molecular chain in which the structural unit (1) is repeatedly bonded. R ¹ and R ² may be the same or different. The main chain of R ¹ and R ^{2 only} needs to be a π-electron conjugated chain. It is a combination. The side chain may not be bound to the main chain, or the side chain may be bound. By selecting appropriate main and side chains, conductive organic molecules with various properties can be produced. The chain length of the main chain is more preferably in the range of 1.0 nm to 3.0 nm.

  The conductive organic molecule having a repeating unit represented by the formula (1) includes a first organic molecule represented by the following formula (2) and a second organic molecule represented by the following formula (3). Are alternately supplied to the semiconductor surface and reacted with each other.

(2) OHC—R ¹ —CHO, (3) H ₂ N—R ² —NH ₂
Here, R ¹ and R ² are groups each having a main chain of a π-electron conjugated chain having a main chain length in the range of 0.65 nm to 4.0 nm, as described above.

  An example of the first organic molecule is shown in FIG. 8, and an example of the second organic molecule is shown in FIG. In the production method of the present invention, the molecular chain is elongated by repeating the cycle of alternately supplying the first organic molecule and the second organic molecule. The first and second organic molecules to be supplied on the substrate are common in all cycles in principle. However, different first and second organic molecules are supplied for each cycle as long as the effect of the present invention is obtained. May be.

  When an organic molecule whose main chain has a chain length in the above range is used, it becomes easy to form a conductive organic molecule having a large angle between the substrate surface and the chain axis on the substrate.

R ¹ and R ² preferably have a value of [main chain length] / [width in a direction perpendicular to the chain axis] (hereinafter, sometimes referred to as “aspect ratio”) in the range of 3 to 12. . Thus, by using a molecule having a high aspect ratio, the angle formed by the substrate surface and the chain axis can be particularly increased. The aspect ratio is more preferably in the range of 5-10.

As an example of a group having a preferred aspect ratio, the above R ¹ and R ² may each independently be a group represented by the following formula (4) or formula (5).

 The first organic molecule is supplied to the semiconductor surface on which the amino group is chemically adsorbed, and the amino group reacts with the aldehyde group of the first organic molecule (step (i)). Next, the second organic molecule is supplied to the semiconductor surface, and the aldehyde group of the first organic molecule (the aldehyde group opposite to the aldehyde group reacted with the amino group) is reacted with the amino group of the second organic molecule. (Step (ii)). In addition, the first organic molecule is supplied to the semiconductor surface, and the second organic molecule's amino group (the amino group opposite to the amino group reacted with the aldehyde group) and the first organic molecule's An aldehyde group is reacted (step (iii)). Thereafter, the main chain of conductive organic molecules is grown by repeating the steps (ii) and (iii).

  The conductive organic molecules grown in this way are fixed to the semiconductor surface in a state where the angle formed by the silicon substrate surface and the main chain axis is large. Since the conductive organic molecule is bonded to the semiconductor surface through an azomethine bond (—N═CH—), the conductive organic molecule has good conductivity with the semiconductor surface.

  The substrate temperature when the organic molecules are supplied onto the substrate is preferably near the evaporation temperature of the supplied organic molecules, for example, [evaporation temperature−50 ° C.] or higher, for example, the temperature higher than the evaporation temperature. According to this configuration, unnecessary organic molecules out of the organic molecules supplied onto the substrate are released into the gas phase, so that conductive organic molecules can be efficiently formed as designed. The substrate temperature is preferably set to, for example, [evaporation temperature + 50 ° C.] or less. According to this configuration, the organic molecules supplied on the substrate can be reacted efficiently.

  By repeating the cycle of alternately reacting the first organic molecule and the second organic molecule, a conductive organic molecule having an arbitrary chain length can be formed. Although there is no limitation in particular in the chain length of an electroconductive organic molecule, in an example, it is the range of 1.5 nm-1 micrometer.

  Hereinafter, a method for forming a light-emitting element will be described as an example of a method for bonding conductive organic molecules to a substrate.

(Example 4 )
First, the Si (111) substrate was brought into contact with 5% hydrofluoric acid (hydrofluoric acid) for 5 minutes to treat the surface with hydrogen termination, and then brought into contact with a 50 mM aqueous ammonium sulfite solution to flatten it to the atomic level. An Si (111) plane is obtained. Next, the treated Si substrate is placed in a chamber, and the ammonia gas flow rate is maintained at 50 sccm and the atmospheric pressure is maintained at 2 torr (about 266 Pa). In this state, the surface of the hydrogen-terminated substrate is irradiated with ultraviolet rays from a high-pressure mercury lamp (100 W) through a sapphire window for 24 hours. In this way, a silicon substrate having an amino group bonded to the surface is produced.

  Next, as shown in FIG. 10, the obtained silicon substrate 10 is set on the substrate holder 21 in the chamber of the vacuum evaporation apparatus 20. In the chamber, a vapor deposition source 22 filled with 1,4-bis (4-formylstyryl) benzene, which is a first organic molecule, and a second organic molecule, A vapor deposition source 23 filled with 4,4 ″ -diamino-p-terphenyl (4,4 ″ -Diamino-p-terphenyl) as a molecule is disposed.

Next, the inside of the chamber is evacuated using a turbo molecular pump, and when the pressure becomes 1 × 10 ⁻⁶ Torr (about 1.3 × 10 ⁻⁴ Pa), the substrate holder 21 is heated to 200 ° C. Next, the vapor deposition source 22 is heated to 260 ° C. to evaporate 1,4-bis (4-formylstyryl) benzene, which is the first organic molecule, and the heating is stopped after a predetermined time. Of the first organic molecules that have reached the substrate surface, the molecules that have reacted with the amino groups on the substrate surface are fixed to the substrate surface by chemical bonds, but the molecules that have not reacted are shown in FIG. 11 (a). Re-evaporate. In this manner, a monomolecular layer of the first organic molecule is formed on the substrate.

  Next, the evaporation source 23 is heated to 200 ° C. to evaporate 4,4 ″ -diamino-p-terphenyl, which is the second organic molecule, and the heating is stopped after a certain period of time. The fixed aldehyde group of the first organic molecule and one of the amino groups of the second organic molecule undergo a dehydration condensation reaction to form an azomethine bond, which is highly reactive. This reaction proceeds easily even at room temperature, and by this reaction, the molecular chain of the conductive organic molecule is elongated as shown in FIG.

  By repeating the cycle of alternately supplying the first organic molecule and the second organic molecule 30 times, a polyazomethine thin film having a thickness of about 100 nm can be obtained. Finally, a device is obtained by depositing a patterned metal electrode using a shadow mask. As the metal for the electrode, Au, Ag, Al, Ca, Mg, Na, Li, and alloys thereof can be used.

  The present invention provides a substrate useful for various devices and molecular devices in the field of electronics represented by organic EL elements and organic solar cells, and further provides an organic material-containing device using this substrate. It has great utility value in the technical field.

It is a figure which illustrates the semiconductor surface of the board | substrate of this invention. It is a figure which illustrates reaction which fixes an organic material on the semiconductor surface of the board | substrate of this invention. It is a figure which illustrates another reaction which fixes an organic material to the semiconductor surface of the board | substrate of this invention. 2 is an XPS spectrum of a semiconductor surface obtained from Example 1 and Comparative Example 1. 2 is an FT-IR spectrum of a semiconductor surface obtained from Example 1 and Comparative Example 1. FIG. 3 is an XPS spectrum of a semiconductor surface obtained from Example 2. 2 is an FT-IR spectrum of a semiconductor surface obtained from Example 2. It is a figure which shows the example of the 1st organic molecule which can be used for manufacture of the organic material containing device of this invention. It is a figure which shows the example of the 2nd organic molecule which can be used for manufacture of the organic material containing device of this invention. It is a figure which shows an example of the apparatus used for manufacture of the organic material containing device of this invention. It is a figure which shows typically the manufacturing process of the organic material containing device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Silicon substrate 20 Vacuum deposition apparatus 21 Substrate holder 22, 23 Deposition source

Claims (8)

  A substrate having a Si (111) (1 × 1) plane in which hydrogen atoms and amino groups are chemisorbed and terminated by the hydrogen atoms and amino groups.   2. The substrate according to claim 1, wherein the Si (111) (1 × 1) plane is a flat surface at an atomic level having a periodic step-and-terrace structure.   An organic material-containing device comprising the substrate according to claim 1 and an organic material disposed on the semiconductor surface of the substrate.   An organic material-containing device in which an amino group that terminates the semiconductor surface of the substrate according to claim 1 and an organic molecule are reacted to fix the organic molecule to the semiconductor surface. The organic material-containing device according to claim 4 , wherein a carbon atom contained in the organic molecule and a nitrogen atom contained in the amino group form a bond CN. The organic material-containing device according to claim 4 , wherein a carbon atom contained in the organic molecule and a nitrogen atom contained in the amino group form a double bond C═N. The organic material-containing device according to claim 4 , wherein the organic molecule contains (—CH═N—). The organic material-containing device according to claim 7 , wherein the organic molecule is a conductive organic molecule having a repeating unit represented by the following formula (1).
(1) —R ¹ —CH═N—R ² —N═CH—
However, R ¹ and R ² are each independently a group having a main chain of a π-electron conjugated chain having a main chain length in the range of 0.65 nm to 4.0 nm.

Images