JP2001308355A - Electrical equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electrical equipment that has a photovoltaic element and uses power generated when the photovoltaic element is irradiated with light as a heat source, light source, power source or control signal, wherein, even in a situation where only light with low intensity of, for example, 50 mW/cm2 or lower, particularly, 10 mW/cm2 or lower, can be irradiated, for example, indoors, its functions are not deteriorated and no additional components are required to secure the functions. SOLUTION: As a photovoltaic element used is a photovoltaic element including as a component a laminate wherein an n-type impurity semiconductor silicon thin film and a p-type impurity semiconductor silicon thin film are bonded via an intrinsic semiconductor silicon thin film, and at least one of those silicon thin films is a silicon thin film containing chlorine atoms at a concentration of, for example, 0.005 to 5 atom.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric device which uses a power generated by irradiating a photovoltaic element with light having a lower intensity than sunlight such as a fluorescent lamp.

[0002]

2. Description of the Related Art Photovoltaic elements such as solar cells have been developed in order to solve the energy problem, and many electric appliances driven by the power obtained by the operation of such photovoltaic elements have been put into practical use. Have been.

A photovoltaic element used in such an electric device generally has a silicon-based thin film as an n-type impurity semiconductor and a silicon-based thin film as a p-type impurity semiconductor via a silicon-based thin film as an intrinsic semiconductor. The laminated body is a constituent element, and a silicon-based thin film made of amorphous silicon is widely used from the viewpoint of high light responsiveness to visible light.

[0004]

However, among the above-mentioned electric appliances, those which are used in a situation where only low intensity light can be irradiated, such as indoors, such as a table clock and a calculator (desktop computer), are not suitable. Since the light applied to the electromotive element is light of weak intensity such as a fluorescent lamp, it is difficult to obtain a sufficient open-circuit voltage, which causes a reduction in functions or a large increase in power consumption, thereby greatly limiting multi-functionalization. Problem.

In a device such as a fully automatic camera (so-called autofocus camera), a photovoltaic element (photodiode type silicon light receiving element) using amorphous silicon is used as a photometric means. The apparatus uses the open-circuit voltage of the photovoltaic element as a control signal and sets the optimal shooting conditions. However, when the photovoltaic element is irradiated with low-illumination light, the open-circuit voltage is low. In order to reproduce output characteristics with good linearity over a wide illuminance range, a temperature detection device and a temperature correction circuit are attached.
As described in Japanese Patent Application Publication No. 76-76, there is a problem that the element structure must be complicated.

As described above, no electric appliance having a photovoltaic element capable of obtaining a high open-circuit voltage even when irradiated with light of weak intensity has not been known, and such an electric appliance has been demanded. .

[0007]

Means for Solving the Problems The present inventors have developed a high-speed film-forming method for silicon-based thin films using a halogenated silane such as dichlorosilane, and applied the film-forming method. The photovoltaic element has been found to have high light stability and has already been proposed (JP-A-6-326043).

As a part of the evaluation of the characteristics of the photovoltaic element, the present inventors examined the relationship between the intensity of the light to be irradiated and the open-circuit voltage. The inventors have found that the device exhibits a higher open-circuit voltage than a conventional photovoltaic device, and have conceived that the problem can be solved by using the photovoltaic device, thereby completing the present invention.

That is, the present invention has a photovoltaic element, and emits electric power generated when the photovoltaic element is irradiated with light having an intensity of 50 mW / cm ² or less mainly as a heat source, a light source, a power source, or An electrical device used as a control signal,
In the photovoltaic element, a silicon-based thin film as an n-type impurity semiconductor and a silicon-based thin film as a p-type impurity semiconductor are joined via a silicon-based thin film as an intrinsic semiconductor, and at least one of the silicon-based thin films is chlorine-based. An electric device characterized by comprising, as a constituent element, a laminate that is a silicon-based thin film containing atoms.

[0010] The photovoltaic element used in electrical equipment of the present invention, for example, open-circuit voltage of 70% or more at 100 mW / cm ² irradiation at the time of irradiation with white light at an intensity of 50~0.1mW / cm ² In addition to the white light
The open-circuit voltage when irradiating with an intensity of ~ 1 mW / cm ² is 1
Because it has a feature that is 00mW / cm ² over 80% of the radiation, 50 mW / cm ² or less, particularly 10 mW /
cm ² , or 1 mW / cm ² or less, further 0.1 mW / cm ²
An effective open-circuit voltage can be obtained even when light of weak intensity of a level of cm ² or less is irradiated. And as a result,
Not only is the use environment greatly relaxed (it works even in dimly lit environments), but the open-circuit voltage is used as an energy source to achieve higher functionality and control the open-circuit voltage. , It is possible to easily perform highly reliable control.

Further, in the electric equipment of the present invention, the amount of chlorine atoms contained in the chlorine-containing silicon-based thin film constituting the photovoltaic element is 0.005 atomic% to 5 atomic%.
With an atomic percentage, an effective open-circuit voltage can be obtained even when the device is irradiated with light having a particularly low intensity.

In general, the performance of a photovoltaic element is determined by the product of an open-circuit voltage, a short-circuit current, and a form factor. The open-circuit voltage is determined by the Fermi level of the p-layer, the i-layer, and the n-layer, and the short-circuit current is determined by the power generation layer. It is determined by the thickness. Normally, a linear linear relationship is obtained between the short-circuit current and the intensity of light applied to the element, but such a relationship is not observed with respect to the open-circuit voltage, and the intensity of the applied light increases. In this case, the open-circuit voltage suddenly rises from a certain light intensity. Therefore, in order to generate an effective open circuit voltage, light of a certain intensity must be irradiated. The present invention
Without being bound by theory, in the photovoltaic device used in the present invention, the purity of the i-layer is high, and the Fermi level of the i-layer is higher than that of the holes generated by the photogenerated carriers, particularly the minority carriers. It is presumed that an effective open-circuit voltage can be generated even when irradiated with light of weak intensity, because it is located at an appropriate position for improving the transport characteristics. Therefore, in the electric device of the present invention having the photovoltaic element as described above, not only the short-circuit current,
It is considered that the performance can be maintained high even under an open circuit voltage under a wide range of light irradiation conditions as compared with conventional electric devices.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In an electric device according to the present invention, a silicon-based thin film as an n-type impurity semiconductor and a silicon-based thin film as a p-type impurity semiconductor are joined via a silicon-based thin film as an intrinsic semiconductor. It is very important to have a photovoltaic element comprising a laminate in which at least one of the thin films is a silicon-based thin film containing chlorine atoms.

By having such a photovoltaic element, 50 mW / cm ² or less, particularly 10 mW / cm ² or less,
In addition, even when the device is used by irradiating it with light of a low intensity of 0.1 mW / cm ^2, it is possible to obtain a sufficient energy source (heat source, light source, or reduced power source) capable of coping with high functionality. Thus, it is possible to easily obtain a signal for performing highly reliable control. Note that having the photovoltaic element means that the photovoltaic element is used in an electric device in some form, that is, the photovoltaic element is incorporated in an electric circuit of the electric device. The manner of use (how to incorporate it into an electric circuit) is determined for each electric device, but usually, a normal photovoltaic element conventionally used may be replaced with the photovoltaic element.

The photovoltaic element used in the present invention has n
The silicon-based thin film is composed of a silicon-based thin film, which is a p-type impurity semiconductor, and a silicon-based thin film, which is a p-type impurity semiconductor, joined via a silicon-based thin film as an intrinsic semiconductor. There is no particular difference from the conventional amorphous silicon photoelectric conversion device except that at least one of them is a silicon-based thin film containing a chlorine atom, and its basic structure is a conventional pin-type amorphous silicon photoelectric conversion device. Or an amorphous silicon photoelectric conversion device such as a nip type structure.

FIG. 1 shows a schematic diagram of a typical pin type photoelectric conversion device used in the present invention. In FIG.
(A), (b), and (c) differ only in the location of the blocking layer, and the other structures are the same. That is,
On a substrate 110, a transparent conductive film layer 120, a semiconductor layer 13
0, has a basic structure in which a back electrode 140 is mounted on a semiconductor layer.

Here, as the substrate 110, a conventionally known substrate made of a material such as quartz glass, soda lime glass, single crystal silicon, polycrystalline silicon, stainless steel, ceramics, and heat resistant polymer can be used without any limitation. The thickness and shape of the substrate may be appropriately determined according to the manufacturing apparatus of the photovoltaic device to be used.
A plate or sheet having a size of about 5 mm can be suitably used.

The transparent conductive film layer 120 is made of SnO ₂ , In ₂ O ₃ , ZnO, CdSnO ₄ , T
Any conductive film made of an oxide such as iO _{2 and} having a thickness of at least about 80% light transmittance may be used. When the transparent conductive film layer 120 has a texture structure (fine uneven structure) as disclosed in, for example, JP-A-9-69642 or JP-A-9-283780,
Such a structure is desirable because the “light confinement effect” increases the use efficiency of incident light.

Further, in the photoelectric conversion device of the present invention shown in FIGS. 1B and 1C, before or after laminating the semiconductor layers, blocking is performed on the transparent conductive film layer 120 as necessary. A blocking layer 171 can be formed over the layer 170 or the semiconductor layer 130. This blocking layer has a wider optical gap than the semiconductor layer 130,
The element of Group III in the periodic table or the element of Group V in the periodic table contains 0 ppm to 10000 ppm, preferably 2 to 10 ppm.
A thin film containing 5000 ppm added silicon and carbon as main components, or a thin film containing silicon and nitrogen as main components,
Alternatively, it is a thin film containing silicon and oxygen as main components. When the impurity addition amount is 0 ppm, a blocking layer containing no impurity element is obtained. The thickness is 2-500n
m, preferably 5 to 200 nm. Since the blocking layer has a large optical gap, the leakage of dark current is suppressed, and as a result, the photoelectric conversion characteristics are improved.

When the collector electrode 140 is provided as a back electrode in a pin structure, it is an electrode formed by vapor deposition on the entire surface. When the collector electrode 140 is provided on the light incident side in a nip structure, a metal such as silver is used. It is an electrode formed by vapor deposition in a grid.

In the photoelectric conversion device shown in FIG. 1, the semiconductor layer 130 includes a p-type semiconductor layer 131, an intrinsic semiconductor layer (photoelectric conversion layer) 132, and an n-type semiconductor layer 133. Here, the p-type semiconductor layer 131 has a thickness of 2 to 50 n.
m, preferably 5 to 20 nm, made of silicon containing an element of Group III of the periodic table such as boron or gallium. The n-type semiconductor layer 133 has a thickness of 2 to 50 n.
m, preferably 5 to 20 nm, made of silicon containing an element belonging to Group V of the periodic table such as phosphorus or arsenic. In addition, the photoelectric conversion layer 132 has a thickness of 100 to 1000 nm.
Is a layer made of silicon.

In the photovoltaic element used in the present invention, at least one of the p-type semiconductor layer 131, the intrinsic semiconductor layer (photoelectric conversion layer) 132, and the n-type semiconductor layer 133 contains chlorine atom. Must be contained. When any of the layers does not contain chlorine atoms, sufficient photoelectric conversion characteristics can be obtained when irradiated with strong light, but good photoelectric conversion characteristics cannot be obtained when irradiated with light of low intensity. The layer containing chlorine atoms is not particularly limited, but is preferably the genuine semiconductor layer 132 from the viewpoint that the open-circuit voltage is high when low-intensity light is irradiated. Also,
The amount of chlorine contained is not particularly limited, but is 50 mW / c.
The content of chlorine atoms is preferably 0.005 atomic% to 5 atomic% from the viewpoint that the photoelectric conversion characteristics are good when irradiated with light having a low intensity of not more than m ² , particularly not more than 10 mW / cm ^2. It is suitable. A more preferable chlorine atom content in terms of the effect is 0.01 to 1 atomic%.

The introduction of such an amount of chlorine atoms can be achieved by using monochlorosilane (SiH ₃ Cl), dichlorosilane as a silicon source used for forming a silicon-based film by a chemical vapor deposition method (CVD method). (SiH ₂
Cl _2), trichlorosilane (SiHCl _3), tetrachlorosilane (SiCl ₄₎ general formula, such as SiH _m Cl _{(4- m)}
(However, m is an integer of 0 to 3).

These gases may be used after being diluted with a hydrogen gas, or may be used by mixing them with a hydrogenated silane gas such as monosilane (SiH ₄ ). Furthermore, when a gas containing carbon such as methane is mixed with monosilane as a raw material gas, and a silicon film is manufactured by a general high-frequency plasma CVD method, carbon is mixed into the silicon film to form a silicon film having a wide optical gap. Can be made.

The optical gap ΔG of a normal amorphous silicon film containing no chlorine is 1.70 to 1.75 eV.
The optical gap of the intrinsic semiconductor layer containing chlorine atoms can be changed by changing the concentration of chlorine and the amount of hydrogen contained when the production conditions are controlled. For example, as disclosed in JP-A-6-326047, a chlorine atom content is 0.005 to 5 atom% and a hydrogen atom content is 3
An intrinsic semiconductor layer having a ΔG _i of 1.75 to 2.5 eV at ２５25 atomic% can be obtained. Note that the optical gap can be determined from a Taus plot using a silicon film deposited on a glass substrate with a thickness of about 1000 nm by measuring an optical absorption coefficient with an absorptiometer.

The CVD method for manufacturing the photoelectric conversion element used in the present invention is not particularly limited, and the high-frequency plasma CVD method used for manufacturing a conventional amorphous or polycrystalline silicon photovoltaic device or the like. , Photo CVD, inductively coupled plasma (ICP) CVD, electron cyclotron resonance (E
CR) CVD method, thermal CVD method and the like can be used without limitation.

The electric device of the present invention has the above-described photovoltaic element, and the photovoltaic element has a photovoltaic element of 50 mW / cm ² or less, particularly 10 mW / cm ² or less, or 1 mW / cm ² or less. There is no particular limitation as long as electric power is used as a heat source, a light source, a power source, or a control signal when electric power generated when light having an intensity of 1 mW / cm ² is irradiated. Here, the electric device means a device, a machine, or a device using electric power as a heat source, a light source, or a power source. The electric device of the present invention that uses the power generated when the photovoltaic element is irradiated with light as a control signal means that the electric device of the present invention uses the signal to operate various types of batteries and home power supplies. Means an electric device that performs some control using electric power supplied from a power source as a power source. Further, the electric device of the present invention may be any electric device that can be used under a condition where only light having the above-mentioned intensity can be irradiated in a normal use form, and light having a light intensity exceeding 50 mW / cm ² is irradiated. Of course, it may be used under possible conditions.

Specific examples of such electric equipment of the present invention include desk-top computers, remote controllers for various home appliances, light sensors, various electronic games, table clocks and wall clocks, and various kinds of electric appliances mainly used indoors. Equipment: Automatic focus adjustment device for camera, mobile phone, PHS, wristwatch, various chargers such as car battery charger, radar detector, radio, mobile TV, sign, information board, sensor light, etc. Used outdoors but quite indoors Frequently used electrical equipment and the like are listed.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electrical equipment of the present invention directly reflects the photoelectric conversion characteristics of the photovoltaic element used. Therefore, the characteristics of the photovoltaic element used in the present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

In each of the examples and comparative examples, each thin film was formed by the plasma CVD apparatus 2 having the basic structure shown in FIG.
00 was used.

The apparatus is mainly composed of each reaction vessel (220, 220).
230), a sample introduction chamber 210, a vacuum pump (mechanical booster pump 221, a turbomolecular pump 222, and an oil diffusion pump 231) communicating with each reaction vessel and the sample introduction chamber, and a plasma generation electrode ( High-frequency generator (24 not shown)
1, 242) and a gas supply device (251, 252) communicating with each reaction vessel. A gate valve 271 and a gate valve 271 are provided between each reaction vessel and the sample introduction chamber.
272 is installed, and the transfer rod 260
The sample (the photoelectric conversion device in the manufacturing process) can be moved while maintaining a vacuum state by using.

In this apparatus, the reaction vessel is provided with an n-type semiconductor layer or a p-type semiconductor layer by using a capacitively coupled plasma (CCP) generated by applying high frequency power to a parallel plate type counter electrode (not shown). A CCP reaction vessel 220 for forming
Inductively coupled plasma (IC) generated by a high-frequency application coil, which is a ring-shaped plasma generation electrode (not shown)
P) and is divided into an ICP reaction vessel 230 for forming an intrinsic semiconductor layer. Also, in each reaction vessel,
Various source gases can be introduced from the gas supply device 251.

Example 1 First, a quartz glass substrate (24 mm × 16 mm × 0.5 mmt) was set on a substrate holder of a sputtering apparatus (SPC-350 manufactured by Anelva).
A transparent conductive layer made of ZnO having a thickness of 1000 nm was laminated by an argon sputtering method using ZnO as a target. The sputtering was performed at an Ar flow rate of 10 scc.
m, O ₂ gas flow rate 0.02 sccm, pressure 5 mTorr
r, RF power 100 W, substrate temperature 300 ° C., and sputtering time 15 minutes.

The substrate in which the transparent conductive film layer is laminated on the glass substrate in this manner is set in the sample introduction chamber 210 of the plasma CVD apparatus 200, and after performing vacuum suction,
The substrate was transferred to a P reaction vessel 220, and a p-type semiconductor layer having a thickness of about 10 nm was formed by a high-frequency plasma CVD method. In addition,
The conditions at this time were as follows: SiH ₄ flow rate 3 sccm, B ₂ H
₆ (Diluted to 1 vol.% With hydrogen) Flow rate 3scc
m, hydrogen flow rate 30 sccm, CH ₄ flow rate 9 sccm, reaction pressure 100 mTorr, RF power 5 W, substrate temperature 2
The temperature was set to 00 ° C. and the reaction time was set to 1 minute and 30 seconds.

After forming the p-layer, the sample is transferred under vacuum to an ICP reaction vessel 230 having a single-coil plasma generating electrode having a diameter of 10 cm inside, and a 500 nm-thick photoelectric conversion layer is formed by ICP-CVD. Produced. The conditions at this time were as follows: SiH ₄ flow rate 30 sccm, SiH ₂ C
The flow rate of l _{2 was} 0.3 sccm, the RF power was 100 W, the reaction pressure was 20 mTorr, the substrate temperature was 200 ° C., and the reaction time was 30 minutes.

After the formation of the photoelectric conversion layer, the sample was transferred again to the CCP reaction vessel 220, and an n-type semiconductor layer having a thickness of 20 nm was formed by a high-frequency plasma CVD method. The conditions at this time were as follows: SiH ₄ flow rate 20 sccm, PH ₃ (1 v
ol. %), Flow rate 5 sccm, reaction pressure 1
00mTorr, RF power 5W, substrate temperature 200 ° C,
The reaction time was 4 minutes.

After the formation of the n-type semiconductor layer, the sample is placed in the sample introduction chamber 2
After being transferred to No. 10, it was taken out of the plasma CVD apparatus, mounted again on the above-mentioned sputtering apparatus, and a 800 nm metal layer was laminated by an argon sputtering method using silver as a target. The sputtering was performed at an Ar flow rate of 1
0 sccm, pressure 5 mTorr, RF power 200 W,
This was performed under the conditions of a substrate temperature of 200 ° C. and a sputtering time of 20 minutes.

The IV characteristics of the thus obtained photoelectric conversion device were measured. The measurement of the IV characteristics was performed using a microammeter (4140 manufactured by Hewlett-Packard Company).
B) was performed using a 100 mW / cm ² simulated solar light source. In order to change the light intensity, the measurement was performed using a neutral density filter under irradiation of pseudo sunlight of 0.1 to 100 mW / cm ² .

The open circuit voltage was determined from the obtained IV characteristic curve and plotted against the light intensity. The results shown in Table 1 were obtained. At this time, the open circuit voltage obtained when light having an intensity of 100 mW / cm ² was incident was normalized as 1.

[0040]

[Table 1]

Comparative Example 1 An optical semiconductor device was manufactured in the same manner as in Example 1 except that only SiH ₄ was used as a raw material gas when producing the photoelectric conversion layer. The open-circuit voltage of the obtained photoelectric conversion element was determined in the same manner as in Example 1, and the results shown in Table 1 were obtained.

As shown in Table 1, the photovoltaic device of Example 1 was 50 mW / c in comparison with the photovoltaic device of Comparative Example 1.
It can be seen that the open-circuit voltage is improved when light having an intensity of m ² or less is irradiated. The effect of the improvement is weak light intensity (for example, 10 mW / cm ² or less, particularly 1 mW / cm ²
cm ² or less).

[0043]

The electric device of the present invention has a photovoltaic element capable of generating a high open-circuit voltage even when irradiated with low-intensity light, so that the use environment is greatly restricted. It is possible to not only ease (function in a dim environment) but also to further enhance the functions of electric equipment mainly used indoors. Further, by using the open-circuit voltage obtained from the photovoltaic element as a control signal, highly reliable control can be easily performed.

[0044]

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a photoelectric conversion device used in the present invention.

FIG. 2 is a schematic view of a plasma CVD apparatus used in Examples and Comparative Examples.

[Explanation of symbols]

 110 ... substrate 120 ... transparent conductive film layer 130 ... semiconductor layer 131 ... p-type semiconductor layer 132 ... intrinsic semiconductor layer 133 ... n-type semiconductor layer 140 ... current collecting electrode 170 , 171: Blocking layer 200: Plasma CVD device 210: Sample introduction chamber 220: CCP reaction container 221: Mechanical booster pump 222: Turbomolecular pump 230: ICP reaction container 231, oil diffusion pumps 241, 242 ... high frequency generators 251, 252 ... gas supply devices 260 ... transfer rods 271, 272 ... gate valves

Claims (3)

[Claims] 1. A photovoltaic element is used, and power generated when the photovoltaic element is irradiated with light having an intensity of 50 mW / cm ² or less is used as a heat source, a light source, a power source, or a control signal. Wherein the photovoltaic element is formed by bonding a silicon-based thin film as an n-type impurity semiconductor and a silicon-based thin film as a p-type impurity semiconductor via a silicon-based thin film as an intrinsic semiconductor. An electric device comprising a laminate in which at least one of the thin films is a silicon-based thin film containing a chlorine atom. 2. The photovoltaic device according to claim 1, wherein the amount of chlorine atoms contained in the chlorine-containing silicon-based thin film is 0.005 atomic% to 5 atomic%. Electrical equipment as described. 3. A photovoltaic device according to claim 1 or claim 2, open-circuit voltage when irradiated with white light at an intensity of 50~0.1mW / cm ² is at 100 mW / cm ² irradiation The electric device according to claim 1, wherein the electric device is a photovoltaic device having 70% or more.