JP2003292062A - Container or food tray coated with semiconductor film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a utilization method of an oxide semiconductor over a wide range which is gentle to the environment and harmless to the human body since semiconductor manufacturing technics and carrier-controlling technics have been drastically improved, and the range of semiconductors is currently extended to oxides. <P>SOLUTION: By using the food tray, directly heat-cooking can be done by forming an oxide semiconductor film which is gentle to the environment and harmless to the human body on the internal surface of the food tray. Therefore, a cooker is not required for the heat-cooking of a food material, and transferring the food material to another container is not necessary, and a space and energy can be saved. In addition, by this manufacturing method, a semiconductor food tray can be quickly mass-produced at a low cost. Also, every kind of substance which can withstand a baking temperature such as metals, ceramics, glass, heat-resistant plastics and others can be used as the food tray, and the wide application in the social life can be expected, and thus, the large industrial propagation effect can be expected. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to coat an inner surface of an object with a semiconductor thin film, and to energize and heat the semiconductor thin film to heat an object contained in the object. It is characterized in that it can be cooked by using it on the inner surface of tableware, and as the semiconductor, oxide semiconductor and nitride semiconductor harmless to the human body are used, and the structure of tableware that can be heated with foodstuffs in it and its manufacture It is about the method. More specifically, zinc oxide and zinc oxide compounds doped with elements such as aluminum, boron, gallium, and indium are used as the n-type oxide semiconductor, and nitrides doped with elements such as silicon are used as the n-type nitride semiconductor. TECHNICAL FIELD The present invention relates to a tableware that forms an electric heating layer on the inner surface of a tableware using gallium and a gallium nitride compound, and is a tableware that can be cooked at the same time as a tableware by semiconductor electric heating, and a method for producing the tableware.

[0002]

2. Description of the Related Art Conventionally, when heating foodstuffs, the foodstuffs are placed in a heating container such as a pan and heated, and the heated foodstuffs are transferred to tableware. In recent years, with the advent of microwave ovens, it has become possible to heat food ingredients in the form of tableware. However, the microwave oven is a cooking utensil, and it is not heated unless the tableware on which the food is placed is placed in the cooking utensil. In other words, it was impossible to directly heat the ingredients on the table on the table.

[0003]

As can be seen from the above microwave oven, it has hitherto been impossible to heat the food material placed on the tableware on the table. This problem should be solved if the dishes have heating capability.

[0004]

According to the present invention, a semiconductor thin film is formed on the inner surface of tableware so that heat treatment can be performed while food is placed on the tableware.

[0005]

Principle and Action of the Invention The origin of the present invention is the existence of a transparent oxide semiconductor as a transparent conductive material. Figure 3
Shows the forbidden band width of the main oxide transparent conductive material and the energy from the vacuum level of its conduction band and valence band.

Referring to FIG. 3, in the oxide semiconductor, the energy of the forbidden band between the lower end of the conduction band and the upper end of the valence band is
It can be seen that zinc oxide, indium oxide, etc., which are larger than the energy in the entire visible light wavelength range, exist.

[0007] Previous studies on oxide semiconductors have revealed that doped zinc oxide and indium oxide have high electron concentration while maintaining high visible light transmittance, and have excellent conductivity.

From this, it can be predicted that tableware in which the transparent semiconductor thin film is electrically heated is realized.

[0009]

Example 1 As shown in FIG. 1, cookable dishes using a transparent semiconductor thin film of zinc oxide were prepared based on this prediction. FIG. 2 shows a part of the tableware of FIG. 1 in an enlarged manner. A semiconductor conductive heater is laminated on the tableware pottery part, and an insulating thin film is laminated on it.

The parameters that are important in the transparent semiconductor thin film heating tableware of the present invention are: (1) Resistivity controllability capable of designing heaters of all characteristics. (2) Does not impair the beautiful appearance of tableware. (3) In terms of food hygiene, no substances harmful to the human body are generated. These are the above three points. Examples in which an n-type zinc oxide semiconductor thin film is used for the inner surface of tableware will be described below.

First, the first point of the two important parameters in the transparent semiconductor thin film heating tableware of the present invention described above is as follows: (1) Resistivity controllability capable of designing heaters of all characteristics. FIG. 5 shows the electron concentration dependence of the resistivity of the zinc oxide transparent semiconductor thin film in the example. The resistivity of the zinc oxide transparent semiconductor thin film, 4x10 ³ from the low-resistance metal par of 2x10 ^-4 [Omega] cm
It was possible to control up to a high resistance region of Ωcm (see Fig. 4). Silicon used for electrical heating for comparison
An example of (n-Si) is shown in FIG.

As can be seen from the comparison between zinc oxide and silicon in FIG. 5, it was found that the zinc oxide transparent semiconductor thin film of the obtained example can realize the same specific resistance as that of silicon.

From this, it is understood that the zinc oxide transparent semiconductor thin film in the example has a heater characteristic comparable to that of silicon used for electric heating.

Further, although it is a surface insulating layer which prevents the conduction of current to the food material, the fact that it can be formed of zinc oxide, which is harmless to the human body like the heater, can be formed from the resistance controllability covering the high resistance region shown in FIG. It can be understood.

[0015]

[Embodiment 2] Next, the second point of the three important parameters in the transparent semiconductor thin film heated tableware of the present invention is as follows: (2) The beautiful appearance of the tableware is not impaired. about. FIG. 6 shows the wavelength dependence of the light transmittance of the zinc oxide semiconductor thin film in the example. The wavelength of light visible to human eyes, that is, visible light is approximately in the range of 380 nm to 780 nm, as shown in FIG. It can be seen from FIG. 6 that the transmittance of the zinc oxide semiconductor thin film in the example exceeds 95% in this wavelength region. From this, it can be seen that the zinc oxide semiconductor thin film in the examples does not impair the beautiful appearance of the tableware at all, even if formed on the tableware with a beautiful pattern or pattern, all of them penetrate and are visible.

FIG. 7 shows an operation test example of the semiconductor thin film heated tableware of the present invention. Assuming that a household power supply is used, the applied voltage is 100V. The transparent semiconductor thin film including glass in this example had a transmittance of 90% or more over the entire visible light range. Aluminum-doped zinc oxide was used as the transparent semiconductor thin film, and the thickness of the thin film was 1 μm. The temperature was measured on the surface of the thin film. As can be seen from FIG. 7, it can be seen that the thin film surface reaches the temperature at which water evaporates within 20 seconds. From this, it can be seen that it can be used as an excellent tableware that can instantly heat food.

[0017]

[Embodiment 3] An example of a method for producing a semiconductor thin film heated tableware according to the present invention will be described. As the cheapest method for producing a large area, there are a sputtering method, a vapor deposition method, and a sol-gel method. Figure 8
Shows the outline of the sol-gel method.

FIG. 9 shows an example of a manufacturing process using the sol-gel method shown in FIG. FIG. 9 illustrates a process for producing transparent semiconductor thin film heated tableware by the dipping method among them. A transparent semiconductor thin film is formed by immersing tableware such as pottery, glass, and heat-resistant plastic in a mixed solution of an organic metal material, which is a transparent semiconductor thin film material, drying and reacting with heating. As shown in FIG. 9, the solvent is ethanol and the metallic zinc is an acetic acid compound, which is harmless to the human body.

[0019]

Fourth Embodiment FIG. 10 shows an example of a manufacturing process using a method of evaporating a raw material target. Pottery, glass,
Tableware such as heat-resistant plastic is placed in a vacuum tank and placed at a position where elements from the target, which is a semiconductor thin film material, can be deposited on the tableware. The semiconductor element is removed from the raw material target to form a thin film on the tableware. After film formation, it is taken out into the atmosphere. As shown in FIG. 10, when argon plasma is used for evaporation of the raw material target and zinc oxide is used as a semiconductor, argon is harmless to the human body, and zinc oxide as the raw material target is also harmless to the human body. I know there isn't. In addition, this manufacturing method has already achieved a film formation time of 60 seconds and a sheet resistance of 10 Ω / □ at a semiconductor film thickness of 200 nm.

[0020]

EFFECTS OF THE INVENTION The present invention lies in the fact that by forming a zinc oxide transparent semiconductor thin film on a surface of a tableware, which can be easily manufactured in a large area, cooking can be performed by electric heating. Therefore,
It is not necessary to heat using a cooking utensil such as a microwave oven, which has been conventionally used, and it is possible to heat and cook at the table while placing the food on the tableware, thus saving space and improving time efficiency. Also, because it does not need to be transferred to tableware, or
Since the food can be eaten while heating, there is little energy loss due to the cooling of the food and it is also energy saving.

[Brief description of drawings]

FIG. 1 Example of heated tableware using a transparent semiconductor thin film heater

[Fig. 2] Example of cross-sectional structure of heated tableware using a transparent semiconductor thin film heater

FIG. 3 Band diagram of an oxide semiconductor

FIG. 4 Example of dish-shaped tableware

FIG. 5 Dependence of resistivity of zinc oxide transparent semiconductor thin film on electron concentration

FIG. 6 is the wavelength dependence of the light transmittance of the zinc oxide transparent semiconductor thin film in the example.

FIG. 7: Applied voltage of transparent semiconductor thin film heater 100V
Dependence of heating temperature on.

FIG. 8: Outline of sol-gel method (when spin coating is used)

FIG. 9: Manufacturing process of transparent semiconductor thin film heater using dip method

FIG. 10: Example of manufacturing method using evaporation of raw material target

Claims (6)

[Claims] 1. A container coated with a semiconductor thin film, characterized in that the inner surface of the container is coated with a semiconductor thin film, and the thin film is energized to generate heat. 2. The container coated with a semiconductor thin film according to claim 1, wherein the container is a heat resistant container. 3. The container coated with a semiconductor thin film according to claim 1, wherein the container is made of ceramics, heat-resistant glass or heat-resistant plastic. 4. The container coated with a semiconductor thin film according to claim 1, wherein the container is used as tableware. 5. The container coated with a semiconductor thin film according to claim 1, wherein the semiconductor thin film is a semiconductor thin film which does not generate a harmful substance to a human body even when energized and heated. 6. The semiconductor thin film according to claim 1, wherein the semiconductor thin film is indium tin oxide, indium oxide, zinc oxide, magnesium zinc oxide, gallium nitride, aluminum gallium nitride or silicon carbide. Container.