SEMICONDUCTOR MATERIAL AND MULTILAYER SEMICONDUCTOR MATERIAL

Abstract

A semiconductor material and a multilayer semiconductor material are earth-conscious and are less harmful to living organisms. The semiconductor material has fibers containing, as a main component, a filament derived from at least any one of a wood material, a plant fiber (pulp), an animal, an alga, a microorganism and a product produced by a microorganism, and has N-type negative resistance. It is preferred that the fibers include bundles of cellulose nanofibers (CNFs), and the width of each of the bundles be 30 to 50 nm. It is also preferred that the fibers are fibers in which a plurality of hydroxy groups and a plurality of carbonyl groups be bound to cellulose.

Claims

1. A semiconductor material, having fibers containing, as a main component, a filament derived from at least any one of a wood material, a plant fiber (pulp), an animal, an alga, a microorganism and a product produced by a microorganism, and having N-type negative resistance.

2. The semiconductor material according to claim 1, which is an n-type semiconductor.

3. The semiconductor material according to claim 1, wherein the fibers comprise bundles of cellulose nanofibers (CNFs) and a width of the bundles is 30 to 50 nm.

4. The semiconductor material according to claim 1, wherein the fibers comprise bundles of cellulose nanofibers (CNFs) and an aspect ratio of the bundles is 1 to 200.

5. The semiconductor material according to claim 1, wherein the fibers are fibers in which a plurality of hydroxy groups and a plurality of carbonyl groups are bound to cellulose.

6. The semiconductor material according to claim 1, comprising a bulk semiconductor represented by an equivalent circuit in which a first RC parallel circuit and a second RC parallel circuit are connected in parallel, wherein the second RC parallel circuit has resistance with a greater resistance value than that of resistance of the first RC parallel circuit and a condenser with a greater capacity than that of a condenser of the first RC parallel circuit.

7. The semiconductor material according to claim 1, wherein the fibers are amorphous.

8. A multilayer semiconductor material, comprising a laminated body in which a plurality of the semiconductor materials according to claim 1 are laminated.

9. The semiconductor material according to claim 2, wherein the fibers comprise bundles of cellulose nanofibers (CNFs) and a width of the bundles is 30 to 50 nm.

10. The semiconductor material according to claim 2, wherein the fibers comprise bundles of cellulose nanofibers (CNFs) and an aspect ratio of the bundles is 1 to 200.

11. The semiconductor material according to claim 2, wherein the fibers are fibers in which a plurality of hydroxy groups and a plurality of carbonyl groups are bound to cellulose.

12. The semiconductor material according to claim 2, comprising a bulk semiconductor represented by an equivalent circuit in which a first RC parallel circuit and a second RC parallel circuit are connected in parallel, wherein the second RC parallel circuit has resistance with a greater resistance value than that of resistance of the first RC parallel circuit and a condenser with a greater capacity than that of a condenser of the first RC parallel circuit.

13. The semiconductor material according to claim 2, wherein the fibers are amorphous.

14. A multilayer semiconductor material, comprising a laminated body in which a plurality of the semiconductor materials according to claim 2 are laminated.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 is an electric circuit diagram showing an equivalent circuit of a semiconductor material in the embodiment of the present invention.

[0028] FIG. 2 is an atomic force microscope (AFM) image of the surface of a mechanically defibrated sheet, a semiconductor material in the embodiment of the present invention.

[0029] FIG. 3 is an XRD spectrum of the mechanically defibrated sheet, a semiconductor material in the embodiment of the present invention.

[0030] FIG. 4 is a complex plane impedance graph and a Nyquist diagram of the mechanically defibrated sheet, a semiconductor material in the embodiment of the present invention.

[0031] FIG. 5 is a graph showing current-voltage characteristics of the mechanically defibrated sheet, a semiconductor material in the embodiment of the present invention.

[0032] FIG. 6 is a graph showing the frequency analysis results of current when applying a high voltage, of the mechanically defibrated sheet, a semiconductor material in the embodiment of the present invention.

[0033] FIG. 7 is a graph showing resistance-voltage characteristics of the mechanically defibrated sheet, a semiconductor material in the embodiment of the present invention.

[0034] FIG. 8 is a complex plane impedance graph of a phosphorylated defibrated sheet, a semiconductor material in the embodiment of the present invention.

[0035] FIG. 9 is a graph showing current-voltage characteristics of the phosphorylated defibrated sheet, a semiconductor material in the embodiment of the present invention.

[0036] FIG. 10 is a graph showing resistance-voltage characteristics of the phosphorylated defibrated sheet, a semiconductor material in the embodiment of the present invention.

[0037] FIG. 11 is a complex plane impedance graph of a chitosan sheet, a semiconductor material in the embodiment of the present invention.

[0038] FIG. 12 is a graph showing current-voltage characteristics of the chitosan sheet, a semiconductor material in the embodiment of the present invention.

[0039] FIG. 13 is a graph showing the frequency analysis results of current in an N-type negative resistance region of the chitosan sheet, a semiconductor material in the embodiment of the present invention.

[0040] FIG. 14 are side views (a) to (c), a perspective view (d) and a side view (e) showing a method for producing a multilayer semiconductor material in the embodiment of the present invention by a MEMS method.

DETAILED DESCRIPTION OF THE INVENTION

[0041] The embodiment of the present invention will now be described based on the drawings and Examples.

[0042] FIG. 1 to FIG. 13 show a semiconductor material in the embodiment of the present invention.

[0043] The semiconductor material in the embodiment of the present invention includes a bulk semiconductor, and has fibers containing, as a main component, a filament derived from at least any one of a wood material, a plant fiber (pulp), an animal, an alga, a microorganism and a product produced by a microorganism. As shown in the structural formula below, the fibers includes a filament in which hydroxyl groups (OH groups) and carbonyl groups (CO groups) are bound to cellulose, a polysaccharide, represented by the molecular formula (C.sub.6H.sub.10O.sub.5).sub.n.

##STR00001##

[0044] The fibers include, for example, pulp, a cellulose fiber or a cellulose nanofiber (CNF). In addition, the fibers are amorphous, but nanocrystals may exist therein. In addition, the fibers may have an atomic vacancy. The fibers are formed using a wood material or a plant fiber (pulp) as a raw material by a mechanical defibration method or a chemical defibration method such as a phosphate esterification method.

[0045] Subsequently, the action will be described.

[0046] In the semiconductor material in the embodiment of the present invention, the fibers have cellulose in which -glucoses are polymerized, and thus the molecules are bound by hydrogen bonds to easily form a thin film sheet shape. In addition, hydroxyl groups (OH group) and carbonyl groups (CO group) are bound to the cellulose, and thus by behavior like chained protonic solitons, an electric double layer, a base of proton transfer, can be instantly formed. A high dielectric domain structure is formed by the formed electric double layer, and also proton tunneling (solitonized proton) is formed by the quantum size effect, and therefore semiconductor characteristics can be expressed.

[0047] FIG. 1 shows an equivalent circuit of a semiconductor material in the embodiment of the present invention. As shown in FIG. 1, the semiconductor material in the embodiment of the present invention is represented by an equivalent circuit in which a first RC parallel circuit 11 and a second RC parallel circuit 12 are connected in parallel, and the second RC parallel circuit 12 has resistance R.sub.2 with a greater resistance value than that of resistance R.sub.1 of the first RC parallel circuit 11, and a condenser C.sub.2 with a greater capacity than that of a condenser C.sub.1 of the first RC parallel circuit 11. The first RC parallel circuit 11 and the second RC parallel circuit 12 indicate an electric double layer in the fibers, and therefore semiconductor characteristics can be expressed.

[0048] The semiconductor material in the embodiment of the present invention includes fibers containing, as a main component, a filament derived from at least any one of a wood material, a plant fiber (pulp), an animal, an alga, a microorganism and a product produced by a microorganism, is earth-conscious and is less harmful to living organisms.

[0049] Hereinafter, semiconductor materials in the embodiment of the present invention were produced as Examples and various measurements were carried out. It should be noted that Examples below are provided only for the illustration of the present invention and the reference of specific aspects thereof, and do not limit and restrict the scope of the invention disclosed in the present application.

Example 1

<Sample 1>

[0050] A semiconductor material of sample 1 in the embodiment of the present invention was produced as described below.

[0051] Kenaf stems from Bangladesh were used as a raw material, the kenaf stems were dried and stored and then soaked in 20 C. water for two weeks. After two weeks, the white bark on the surface thereof was peeled and dried. After drying it was defibrated by a high-pressure homogenizer to obtain pulped fibers (bast fibers). The sheet-shaped pulp was soaked in distilled water at a concentration of 3% for 5 hours and disintegrated by a pulper for 30 minutes. For the disintegrated slurry, 2% disintegrated pulp was crushed by a planetary ball mill using a zirconium ball at a rotation number of 100 rpm for 10 hours. After crushing, the 2% disintegrated pulp crushed slurry was dropped on the Si substrate of a spin coater and rotated at 500 rpm to produce a thin film. After this, water was vaporized and dried on a 100 C. hot plate to make a kenaf sheet.

[0052] The surface of the sheet-shaped sample 1 was observed by an atomic force microscope (AFM), and the results are shown in FIG. 2. As shown in FIG. 2, it was verified that a number of long and thin substances with a width of 30 to 50 nm were distributed on the surface of the sample 1. The width of each of CNFs is 3 to 4 nm, and thus these substances are considered to be the bundles of CNFs.

[0053] The sample 1 was analyzed by an X-ray diffraction (XRD) method. The obtained XRD spectrum is shown in FIG. 3. As shown in FIG. 3, broad peaks were recognized, and thus it was verified that the sample 1 was amorphous.

[0054] It was also verified that in the sample 1, the measured density was 1.6 g/cm.sup.3 and the specific gravity was low, 2 or less. It was also verified that the sample 1 could operate in a range of-269 C. to 200 C. up to 300 V in a furnace for low and medium temperatures. In addition, the specific surface area of the sample 1 was measured by a BET method, and the result was 800 m.sup.2/g.

[0055] A pair of metal electrodes were provided on both surfaces of the sample 1 in a thin film sheet shape so that the sample 1 was placed between the electrodes, and various measurements were carried out. First, an AC signal was applied between the electrodes by an AC impedance method, and the absolute value of impedance and the phase difference of voltage and current of the sample 1 were measured. It should be noted that both the electrodes are Al electrodes. A graph obtained by plotting the measurement results on a complex plane is shown in FIG. 4. As shown in FIG. 4, it was verified that the measurement results were plotted along a shape having two small and large aligned arcs. From the results, the sample 1 is considered to be represented by the equivalent circuit shown in FIG. 1.

[0056] Therefore, in the equivalent circuit shown in FIG. 1, the electrical resistivity of resistances R.sub.1 and R.sub.2 and the electrical capacity of the condensers C.sub.1 and C.sub.2 were changed, and the Nyquist diagram corresponding best with the measurement results shown in FIG. 4 was obtained by the least squares method and is shown with the solid line in FIG. 4. The electrical resistivity and the electrical capacity at this time were R.sub.1=0.35 km, R.sub.2=8 km, C.sub.1=210.sup.9 F and C.sub.2=510.sup.8 F.

[0057] As shown in FIG. 4, the measurement results and the Nyquist diagram almost correspond with each other, and thus it was verified that the sample 1 was equivalent to a lumped constant condenser having two macroscopic condensers (electric double layer) shown in FIG. 1, and a semiconductor having two bands, a low current low resistance band and a high current high resistance band, was formed. From the results, the sample 1 is considered to express the phenomenon of not a pn junction but bulk semiconductor.

[0058] Next, a voltage was applied between the electrodes of the sample 1 to measure current-voltage characteristics at room temperature. The results are shown in FIG. 5. As shown in FIG. 5, it was verified that current was reduced between about 15 and 33 V and the sample 1 showed N-type negative resistance. From the results, it can be said that the sample 1 is a semiconductor.

[0059] In addition, a voltage was applied between the electrodes of the sample 1 to measure current flowing between the electrodes, and the frequency analysis was carried out. The results are shown in FIG. 6. As shown in FIG. 6, harmonic peaks were observed at about 1 kHz, 3 kHz and 5 kHz. From the results, the sample 1 is considered to perform DC/AC conversion. It should be noted that the results are similar to the Gunn effect, which is recognized in GaAs (gallium arsenide) semiconductors.

[0060] In addition, a voltage was applied between the electrodes of the sample 1 to measure resistance-voltage characteristics at room temperature. The measurement results are shown in FIG. 7. As shown in FIG. 7, it was verified that the resistance values of the sample 1 rapidly increased from 0 V to about 2 V by about 3 to 4 orders with increases in voltage, and then was reduced by about 3 orders. The results are considered to be due to a switching effect between metal and an insulator. This is considered to be not the effect of a pn junction semiconductor, but the effect of a semiconductor having two bands, a low current low resistance band and a high current high resistance band, specific to an n-type bulk semiconductor having N-type negative resistance.

Example 2

<Sample 2>

[0061] A semiconductor material of sample 2 in the embodiment of the present invention was produced as described below.

[0062] Bleached unbeaten kraft pulp derived from a needle-leaved tree (whiteness 85%) was used as a raw material, and 10 g of the pulp was soaked in a mixed solution of urea (12 g) and NH.sub.4H.sub.2PO.sub.4 (4.5 g) added to distilled water (15 g). The soaked pulp was taken from the mixed solution and dried, and then hardened at 165 C. for 10 minutes. The hardened pulp was put in distilled water to obtain a 2% aqueous solution, and caustic soda was further added thereto to maintain pH 12 and carry out neutralization. The aqueous solution was defibrated by a high-pressure homogenizer to make a dispersed liquid of cellulose fibers with a diameter of 30 to 10 nm. The slurry distributed liquid (2% concentration) was formed into a sheet using a 50 C. heated doctor blade by a doctor blade method.

[0063] It was verified that in the sample 2, the measured density was 1.5 g/cm.sup.3 and the specific gravity was low, 2 or less. It was also verified that the sample 2 could operate in a range of 269 C. to 200 C. up to 300 V in a furnace for low and medium temperatures. In addition, the specific surface area of the sample 2 was measured by a BET method, and the result was 750 m.sup.2/g.

[0064] A pair of metal electrodes were provided on both surfaces of the sample 2 in a thin film sheet shape so that the sample 2 was placed between the electrodes, and various measurements were carried out. First, an AC signal was applied between the electrodes by the AC impedance method, and the absolute value of impedance and the phase difference of voltage and current of the sample 2 were measured. It should be noted that one electrode is an Al electrode and another electrode is a Cu electrode. A graph obtained by plotting the measurement results on a complex plane is shown in FIG. 8. As shown in FIG. 8, it was verified that the measurement results were plotted along a shape having two small and large aligned arcs. From the results, the sample 2 is considered to be represented by the equivalent circuit shown in FIG. 1.

[0065] Therefore, in the equivalent circuit shown in FIG. 1, the electrical resistivity of resistances R.sub.1 and R.sub.2 and the electrical capacity of the condensers C.sub.1 and C.sub.2 were changed, and the Nyquist diagram corresponding best with the measurement results shown in FIG. 8 was obtained by the least squares method. The electrical resistivity and electrical capacity at this time were R.sub.1=1.4 km, R.sub.2=5.7 km, C.sub.1=1.410.sup.6 F and C.sub.2=2.410.sup.5 F.

[0066] The measurement results and the Nyquist diagram almost correspond with each other, and thus it was verified that the sample 2 was equivalent to a lumped constant condenser having two macroscopic condensers (electric double layer) shown in FIG. 1, and a semiconductor having two bands, a low current low resistance band and a high current high resistance band, was formed. From the results, the sample 1 is considered to express the phenomenon of not a pn junction but bulk semiconductor.

[0067] Next, a voltage was applied between the electrodes of the sample 2 to measure current-voltage characteristics at room temperature. The results are shown in FIG. 9. As shown in FIG. 9, it was verified that current was reduced between about 150 and 125 V and the sample 2 showed N-type negative resistance. From the results, it can be said that the sample 2 is a semiconductor.

[0068] In addition, a voltage was applied between the electrodes of the sample 2 to measure resistance-voltage characteristics at room temperature. The measurement results are shown in FIG. 10. As shown in FIG. 10, it was verified that the resistance values of the sample 2 rapidly increased from 0 V to about 2.5 V by about 3 to 4 orders with decreases in voltage, and then was reduced by about 3 orders. The results are considered to be due to a switching effect between metal and an insulator. This is considered to be not the effect of a pn junction semiconductor, but the effect of a semiconductor having two bands, a low current low resistance band and a high current high resistance band, specific to an n-type bulk semiconductor having N-type negative resistance.

Example 3

<Sample 3>

[0069] A semiconductor material of sample 3 in the embodiment of the present invention was produced as described below.

[0070] Chitin isolated from red snow crab shells was used as a raw material, 10 g of the chitin was put in a 48% sodium hydroxide solution, the obtained mixture was boiled at 120 C. for 30 minutes and then separated by filtration, and sodium hydroxide was completely removed by washing with water. The slurry separated by filtration was crushed by a planetary ball mill using a zirconium ball at a rotation number of 200 rpm for 20 hours. The obtained 3% crushed slurry was dropped on the Si substrate of a spin coater, and rotated at 800 rpm to make a thin film. After this, water was vaporized and dried on a 100 C. hot plate to produce a chitosan sheet.

[0071] It was verified that in the sample 3, the measured density was 2.1 g/cm.sup.3 and the specific gravity was relatively low. It was also verified that the sample 3 could operate in a range of 50 C. to 200 C. up to 300 V in a furnace for low and medium temperatures.

[0072] A pair of metal electrodes were provided on both surfaces of the sample 3 in a thin film sheet shape so that the sample 3 was placed between the electrodes, and various measurements were carried out. First, an AC signal was applied between the electrodes by the AC impedance method, and the absolute value of impedance and the phase difference of voltage and current of the sample 3 were measured. It should be noted that one electrode is an Al electrode and another electrode is a Cu electrode. A graph obtained by plotting the measurement results on a complex plane is shown in FIG. 11. As shown in FIG. 11, it was verified that the measurement results were plotted along a shape having roughly two small and large semicircles. From the results, the sample 3 is considered to be represented by the equivalent circuit shown in FIG. 1.

[0073] Therefore, in the equivalent circuit shown in FIG. 1, the electrical resistivity of resistances R.sub.1 and R.sub.2 and the electrical capacity of the condensers C.sub.1 and C.sub.2 were changed, and the Nyquist diagram corresponding best with the measurement results shown in FIG. 11 was obtained by the least squares method. The electrical resistivity and electrical capacity at this time were R.sub.1=R.sub.2=3.8 km, C.sub.1=3.310.sup.7 F and C.sub.2=9.310.sup.7 F.

[0074] The measurement results and the Nyquist diagram almost correspond with each other, and thus it was verified that the sample 3 was equivalent to a lumped constant condenser having two macroscopic condensers (electric double layer) shown in FIG. 1, and a semiconductor having two bands, a low current low resistance band and a high current high resistance band, was formed. From the results, the sample 3 is considered to express the phenomenon of not a pn junction but bulk semiconductor.

[0075] Next, a voltage was applied between the electrodes of the sample 3 to measure current-voltage characteristics at room temperature. In the measurement, a voltage was applied while scanning at a rate of 1.24V/s from about 210 V toward about +30 V. The results are shown in FIG. 12. As shown in FIG. 12, it was verified that the current value vibrated between about 210 V and about 170 V and the sample 3 showed N-type negative resistance. It was also verified that current was zero between 170 V and 0 V because of entering into a resistance region of 100 k; however, current dramatically flowed when entering into a positive voltage region beyond 0 V, and a rectification effect was shown.

[0076] The frequency analysis of the current vibration in the N-type negative resistance region between about 210 V and about 170 V was then carried out by an oscilloscope. The results are shown in FIG. 13. As shown in FIG. 13, the peak was verified at a site where the mean frequency is about 40 MHz. From the results, the sample 3 is considered to perform DC/AC conversion.

[0077] The defibration treatment, fiber state (classification of crystal and formless (amorphous)), density, electrical resistivity and electrical capacity of the sample 1 to sample 3 are summarized and shown in Table 1.

TABLE-US-00001 TABLE 1 Defibration Electrical treatment Density resistivity Electrical Sample Type of Sheet method Fiber state (g/cm.sup.3) (km) capacity (F) 1 Mechanically Mechanical Formless 1.6 R.sub.1 = 0.35 C.sub.1 = 2 10.sup.9 defibrated sheet ball mill R.sub.2 = 1.8 C.sub.2 = 5 10.sup.8 2 Phosphorylated Chemical Formless 1.5 R.sub.1 = 1.4 C.sub.1 = 1.4 10.sup.6 defibrated sheet phosphate (including 5% R.sub.2 = 5.7 C.sub.2 = 2.4 10.sup.5 esterification nanocrystals) 3 Chitosan sheet Mechanical Formless 2.1 R.sub.1 = R.sub.2 = C.sub.1 = 3.3 10.sup.7 ball mill 3.8 C.sub.2 = 9.3 10.sup.7

[0078] FIG. 14 shows a multilayer semiconductor material in the embodiment of the present invention.

[0079] As shown in FIG. 14, the multilayer semiconductor material in the embodiment of the present invention is produced using the sheet-shaped semiconductor material in the embodiment of the present invention by the MEMS method as described below. As shown in FIG. 14 (a), first, a Cu layer (thickness 500 nm) 22 is formed on the surface of a glass substrate (40400.5 mm) 21 by sputtering. Subsequently, a sheet-shaped semiconductor material 10 is put on the Cu layer 22 as shown in FIG. 14 (b), and an Al layer (thickness 500 nm) 23 is further formed thereon by sputtering as shown in FIG. 14 (c). Thereby, a material shown in FIG. 14 (d) having the Cu layer 22 and the Al layer 23 as metal electrodes on both surfaces of the sheet-shaped semiconductor material 10 can be produced. It should be noted that this structure corresponds to those of the materials having metal electrodes on both surfaces of the sample 1 to sample 3 used in various measurements in Examples 1 to 3.

[0080] Subsequently, the glass substrate 21 was removed, and the remaining material was used as a base body. By laminating a plurality of the base bodies, a multilayer semiconductor material 20 in the embodiment of the present invention shown in FIG. 14 (e) can be produced. In the produced multilayer semiconductor material 20, the Al layer 23 on the top of the base bodies and the Cu layer 22 on the bottom of the base bodies are terminals, and a plurality of the semiconductor materials 10 are joined in series.

[0081] As described above, the multilayer semiconductor material 20 in the embodiment of the present invention includes a laminated body in which a plurality of the semiconductor materials 10 in the embodiment of the present invention are laminated, and can be a solid quantum semiconductor in which parallel equivalent circuits are bonded in an electric lumped constant manner.

INDUSTRIAL APPLICABILITY

[0082] The semiconductor material and multilayer semiconductor material according to the present invention can be widely used from the weak electric field of e.g. mobile phones, drones, and wall-mounted televisions, to the strong electric field of e.g. not only motor vehicles but also ships and airplanes. More specifically, they can be utilized for e.g. an AC transmitter, control equipment and an overcurrent prevention switch for microelectronic circuits. They can be also utilized for e.g. electronic and electric infrastructure such as power source modules for e.g. lighting arresters, welding and overdischarging prevention, various amplifiers, microwave oscillators, pump sources of parametric amplifiers, sensors for e.g. police radars, door opening/closing systems, trespass sensing systems, noise filters, pedestrian safe systems, control equipment for microelectronics, remote vibration detectors, shunt regulators, protection circuits and transmitters.

REFERENCE SIGNS LIST

[0083] 10: Semiconductor material [0084] 11: First RC parallel circuit [0085] 12: Second RC parallel circuit [0086] 20: Multilayer semiconductor material [0087] 21: Glass substrate [0088] 22: Cu layer [0089] 23: Al layer