JPS625251A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To increase the sensitivity of a sensitive body and to improve the adhesion to the support by successively laminating a blocking layer and a photoconductive layer each made of microcrystalline silicon contg. a group III or V element on the support. CONSTITUTION:A blocking layer 2, a photoconductive layer 3 and a surface layer 4 are successively laminated on an electrically conductive support 1. The blocking layer 2 and the photoconductive layer 3 are made of microcrystalline silicon contg. a group III or V element in the periodic table. The concn. of the group III or V element is changed in the thickness direction and made higher on the support 1 side. The surface layer 4 is made of Si3N4 or the like and protects the surface. Since microcrystalline silicon is used and the group III or V element is incorporated, the resulting sensitive body can by provided with superior electrostatic charging performance, sensitivity, high heat, moisture and wear resistances.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electrophotographic photoreceptor using microcrystalline silicon.

[Technical background of the invention and its problems] Cd 3%Zn 013e, 3e-Te has conventionally been used as a material constituting the photoconductive layer of an electrophotographic photoreceptor.

Inorganic materials such as amorphous silicon (a-3i),
Organic materials such as poly-N-vinylcarbazole (PVCz) and trinitrofluorene (TNF) are mainly known.

However, these known materials have various problems when used as photoconductive materials, and at present they are used differently depending on the situation, sacrificing the characteristics of the system to some extent.

For example, 3e SCd S is a material that is inherently harmful to the human body, and special considerations for safety measures are required when manufacturing these materials, which may result in complicated manufacturing equipment or unnecessary manufacturing costs. This is expensive, and especially in the case of Se, there is a need for recovery, so there is a problem in that the recovery cost also adds up to the material cost. Also, from a characteristics perspective, for example, 3e and 3e-TO have a low crystallization temperature of 65°C, so crystallization occurs during repeated copying, which tends to cause residual frost and other practical problems. However, it had the disadvantage of a short service life. Furthermore, ZnO has the problem of poor reliability because it is easily oxidized and reduced due to the physical properties of the material and is extremely susceptible to the influence of the environmental atmosphere.

Furthermore, regarding organic photoconductive materials, PVCz, TNF, and the like have the drawbacks of poor thermal stability and abrasion resistance and short product life because they are organic materials.

On the other hand, amorphous silicon has recently attracted attention as a photoelectric conversion material, and is being widely used in solar cells, thin film transistors, and image sensors, and is also being considered as a photoconductive material for electrophotographic photoreceptors. .

When used as an electrophotographic photoreceptor, this amorphous silicon has the following advantages not found in the other materials mentioned above, and is expected to be used as an electrophotographic photoreceptor material.
Studies are already underway on using it as a photoreceptor based on the Carlson method.

■ It is a non-polluting material and does not require collection or disposal.

■It has higher spectral sensitivity in the visible light region than other electrophotographic photoreceptors.

■ High surface hardness, excellent wear resistance and impact resistance.

This amorphous silicon film is generally formed by glow discharge decomposition using silanes as raw materials, but its electrical and optical properties are greatly influenced by the amount of hydrogen incorporated into the film during film formation. be done.

In other words, as more hydrogen is incorporated into the amorphous silicon film, the optical bandgap becomes larger and the resistance becomes higher. This makes it difficult to use with laser beam printers.

As a method to increase the sensitivity to long wavelength light, for example, silanes and germane GeH+ are mixed and a film with a narrow optical band gap is formed by glow discharge decomposition. Class and Q
The optimum substrate temperature differs when eH<, and therefore, the formed film has many structural defects and good photoconductivity cannot be obtained. Furthermore, there is also the problem that the waste gas from QeH becomes toxic when oxidized, making waste gas treatment complicated.

In addition, if the hydrogen content in the amorphous silicon film is high, depending on the film formation conditions, (81H2)n, S+ H2
Those with such bonding structures become dominant in the film, and as a result, the film contains many voids and the number of silicon dangling bonds increases, resulting in poor photoconductivity and making it difficult to use as an electrophotographic photoreceptor. .

Conversely, when the amount of hydrogen incorporated into the amorphous silicon film decreases, the optical bandgap becomes smaller, resulting in lower resistance, but the photosensitivity to long wavelength light increases. However, on the other hand, if the hydrogen content is low, it will not compensate for the dangling bonds of silicon, which will reduce the movement speed and lifetime of the generated carriers, resulting in a decrease in photoconductivity, making it difficult to use as an electrophotographic photoreceptor. Become something.

As described above, the characteristics of amorphous silicon are greatly influenced by the amount of hydrogen taken into it, so there has been a problem that the range of suitable manufacturing conditions is narrow. Another problem was that the rate of formation of the amorphous silicon layer was extremely slow, resulting in extremely low productivity.

Although the use of microcrystalline silicon instead of amorphous silicon is being considered to solve these problems, it is difficult to use a single-layer photoconductor that has both the necessary characteristics of high resistance and high photosensitivity. It was extremely difficult to satisfy them.

[Object of the Invention] The present invention has been made to solve these conventional problems, and therefore has high productivity, high resistance, high sensitivity over a wide wavelength range, good adhesion to the substrate, and durability. The purpose is to provide an electrophotographic photoreceptor with excellent environmental friendliness.

[Summary of the Invention] That is, the present invention provides a blocking layer mainly consisting of microcrystalline silicon containing an element of group Ⅰ or V of the periodic table as an impurity on a conductive support, and a blocking layer containing an element of group Ⅰ or V of the periodic table as an impurity, In an electrophotographic photoreceptor in which a photoconductive layer containing a Group V element as an impurity and consisting mainly of microcrystalline silicon is sequentially formed, the blocking layer and/or the photoconductive layer contains a Group Ⅰ or V group of the periodic table. By changing the concentration of the elements in the film thickness direction and having the maximum concentration near the conductive support side, productivity is improved, high resistance is achieved, and high sensitivity over a wide wavelength range is achieved. It has improved adhesion and environmental resistance.

As shown in FIG. 1, the electrophotographic photoreceptor of the present invention has Aβ
On a conductive support 1 such as
13 are formed in this order, and on this photoconductive layer 3, 3isN and S are formed as necessary for the purpose of protecting this photoconductive layer 3 or preventing light loss due to light reflection on the surface.
iO2,5IC1AJ203, a-8i N
: H, a-8t Qll, a-3i
A surface layer 4 made of an inorganic compound such as C:H or an organic material such as polyvinyl chloride or polyamide is formed.

The thickness of the blocking layer of the electrophotographic photoreceptor of the present invention is 1
The film thickness of the light guiding layer 111 is in the range of 1 to 80 μm, preferably 5 to 50 μm.

In the present invention, both the blocking layer and the photoconductive layer are mainly composed of this microcrystalline silicon, but it is preferable that amorphous silicon is mixed or laminated in at least one layer.

The microcrystalline silicon used in the present invention is
Microcrystalline silicon has the following physical characteristics and is clearly distinguished from amorphous silicon and polycrystalline silicon (polycrystalline silicon).

That is, when performing X-ray diffraction measurements, since amorphous silicon is amorphous, only a halo appears and no diffraction pattern can be observed, but microcrystalline silicon has a crystalline diffraction pattern in the vicinity of 2θ of 27 to 28.5'. , and polycrystalline silicon has a dark resistance of 1
0.6Ω·1 or less, whereas microcrystal silicon has a resistance of 10Ω·1 or more. It is thought that such microcrystal silicon is formed by aggregation of microcrystals with a grain size of approximately several tens of angstroms or more.

The blocking layer in the electrophotographic photoreceptor of the present invention is for preventing charge injection from the conductive support,
In the Carlson process, for example, when the photoreceptor surface is positively charged, a P-type layer is used to prevent the injection of electrons from the support side, and when the photoreceptor surface is negatively charged, it is used to prevent the injection of holes from the support side. N to do
Use as a mold layer.

The impurity elements to be contained in the microcrystalline silicon include elements of group 1II of the periodic table, such as B, Aft, and Ga % ln in the case of P-type.

T1 and the like are preferred, and in the case of N-type, elements of group V of the periodic table, such as N, P, As, Sb, Bi, etc. are preferred. Doping with these P-type impurities and N-type impurities prevents charge from being injected into the photoconductive layer from the support side, improving photosensitivity and making it i-type, resulting in high resistance. .

The concentration of the element of Group 1 or Group V of the periodic table in the blocking layer is made to decrease continuously from the conductive support side to the surface side of the microcrystalline silicon film. This reduction in the concentration of Group II or Group V elements may occur at the same rate or at different rates in the film thickness direction (or, in some cases, it may decrease in stages). Good. Figures 2(a) to <i> show the concentration distribution patterns of impurity elements in the film thickness direction.
The pattern of decrease in impurity element concentration in the present invention may be any of the above. Note that it is desirable that the distribution in a plane parallel to the support be uniform.

These microcrystalline silicon layers in the present invention preferably contain 0.1 to 30 atomic percent of hydrogen atoms. When the hydrogen atoms are contained within this range, the dark resistance and bright resistance ratios become harmonious, and an electrophotographic photoreceptor with excellent photoconductive properties can be obtained. In addition, any one of nitrogen, carbon, and oxygen is present in the microcrystalline silicon layer.
By containing seed elements, the dark resistance is increased,
Photoconductive properties can be improved. These elements precipitate at the grain boundaries of microcrystalline silicon, and also
It is thought that this acts as a terminator for the dangling bonds, reduces the density of states existing in the equilibrium zone between the bands, and produces the above-mentioned effect.

The electrophotographic photoreceptor of the present invention! To manufacture LJ, as in the case of manufacturing a photoreceptor made of amorphous silicon,
Microcrystalline silicon can be deposited on a conductive support by high-frequency glow discharge decomposition using silane gas as a raw material gas, but the temperature of the support is set higher than when forming amorphous silicon, and the high-frequency power is increased. This makes it easier to form. In this way, by increasing the support temperature and increasing the high frequency power, it is possible to increase the flow rate of the raw material gas (silane, etc.).
As a result, the film formation rate can be increased. In addition, microcrystalline silicon is particularly easily formed when the raw material gas is diluted with hydrogen, including a high-order silane gas such as Si H4 or 5i2H*.

FIG. 3 is a diagram schematically showing an example of an apparatus for forming such a microcrystalline silicon film. Third
In the figure, 5.6.7 and 8 are reaction gas cylinders,
For example, raw material gases such as S i H4, B 2 Hs%H2, CH4, etc. are accommodated. These reactant gas cylinders 5 to 8 are distributed via pressure regulators R1 to R4 and flow ff1ll sized pulp v1 to V4! It is connected to the gas mixer 9 via IP1 to P4. And this gas mixer 9
The flow m adjustment is connected to the reaction vessel 10 by a pipe P5 having a valve 5. Inside the reaction vessel 10, there are a cylindrical electrode 11 and a drum base 13 placed on a support base 12.
are arranged concentrically, a cylindrical electrode 11 and a support base 12
A high frequency power source 14 is connected to.

15 is a heating heater disposed within the drum base 13;
Reference numeral 16 designates a rotating shaft of a drum base rotated by a drive motor 20, and reference numeral 18 designates a connection gate valve connected to an exhaust system for obtaining a vacuum necessary for glow discharge.

In order to form microcrystalline silicon on the surface of the drum base 130 using such a device, first the drum base 13 is placed in the reaction vessel 10, and then the exhaust system is operated to exhaust the air to below about 0.1Toor. Thereafter, reaction gases are supplied from the reaction cylinders 5 to 8, and these gases are mixed at a predetermined ratio in the gas mixer 9, and the mixture is introduced into the reaction vessel 10, and the pressure is set at 0.1 to ITorrP2 degrees. Next, while the drum base 13 is rotated by the drive motor 17, power is supplied from the high frequency power supply 14 to cause glow discharge, thereby depositing microcrystalline silicon on the drum base 13. In this case, the drum base 13 is heated in advance to a desired temperature by the heater 15, and is maintained at a constant temperature during film formation. In addition, cylinders 5 to 8 contain raw material gases, such as N201NH3, N201NH3, and
These elements can also be contained in microcrystalline silicon by using O2, H2, CH4, C2H4, Oz gas, etc. Note that when hydrogen is added to the microcrystalline silicon layer by, for example, a glow discharge decomposition method, SiH* or 3i is used as a raw material.
Glow discharge may be performed by introducing silanes such as zHs and hydrogen as a carrier gas into the reaction chamber. In addition, similar methods can be used such as using a mixed gas of silicon halides such as 3iF4 or SiCβ4 and hydrogen, or reacting with a mixed gas system of silanes and halogen or silicon, or using physical methods such as sputtering. microcrystalline silicon containing hydrogen can be obtained.

[Embodiments of the invention] Next, examples of the present invention will be described.

Example Using the electrophotographic photoreceptor manufacturing apparatus shown in FIG. 3, an electrophotographic photoreceptor was manufactured by forming a film of microcrystalline silicon on an Ag support by the glow discharge decomposition method described below. That is, first, the 3i to 14 flow rate is 70SCCM1.
The H2 flow rate was 70,080 CM, 828 s was mixed, and the drum base temperature was 370°C, the applied power was 1 kW, and the reaction pressure was 0.
A blocking layer was formed by forming a film of P-type microcrystalline silicon with a thickness of 1 μm on the drum base under conditions of 7 Torr. Note that the concentration of 82H6 is B2H'*/S! with respect to the flow rate of 51H1 at the start of film formation. H+Evening 10
2, and then gradually decreased as the film formation time progressed.

Next, S! The H4 flow rate was set to 503 CCM, the 1H2 flow rate was set to 50080 CM, and the other conditions were the same as those for forming the blocking film, and the film thickness was 20μ.
A photoconductive layer consisting of a microcrystalline silicon layer of m thickness was formed. The concentration of 82 Hs in this photoconductive layer continues to decrease from the blocking layer to BzHs/S! in this photoconductive layer. The film was formed to have an H* value of about 10. Thereafter, a conventional surface layer was laminated to produce an electrophotographic photoreceptor according to the present invention.

The electrophotographic photoreceptor produced in this way has high dark resistance, excellent charging reaction, good photoconductivity, and sufficient sensitivity not only to visible light but also to long wavelengths in particular. death,
In addition, due to the concentration gradient in the film thickness direction of the elements of Group Ⅰ or V of the periodic table, the adhesiveness was good and the repeatability was excellent.

[Effects of the Invention] As explained above, the electrophotographic photoreceptor of the present invention has high resistance and excellent charging characteristics, and also has high photosensitivity characteristics in the visible light and near-infrared light regions. It is harmless to people and has excellent heat resistance, moisture resistance, and abrasion resistance, so it has the advantage of not deteriorating even after repeated use over a long period of time and has a long life.

In addition, the production is safe and easy, and there is no need for gas such as GeH4 to increase or decrease long wavelengths, so there is no need for extra waste gas treatment equipment, and industrial productivity is extremely high.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing the photoreceptor of the present invention, and FIG. 2 (a) to (λ) show concentration distribution patterns of elements in group Ⅰ or group V of the periodic table in the film thickness direction. The figure shown in FIG. 3 is a diagram schematically showing the manufacturing apparatus. 1... Conductive support 2... Blocking layer 3... Photoconductive layer 4... Surface Layers 5 to 8... Reaction gas cylinder 9... Gas mixer 10... Reaction container 11... Cylindrical electrode 12 ......Support stand 13...Drum base 16...Rotary shaft 17 of drum base
......Drive motor 14...High frequency electrode 15...Heater 18...Connection gate valve R1-R5.
・・・・・・Pressure regulator■1～■5・・・・・・Valve Applicant Higashi Co., Ltd. Applicant Toshiba Automatic Equipment Engineering Co., Ltd. Representative Patent Attorney Sa Suyama - Procedural Amendment (Spontaneous) Showa 6 residence 1 corner 21a 1, Indication of the case Japanese Patent Application No. 1988-143241 2, Name of the invention Electrophotographic photoreceptor 3, Person making the amendment Relationship to the case Patent applicant Horiyo, Saiwai Ward, Yozaki City, Kanagawa Prefecture Town 72 (3o75 Toshiba Corporation 4, Agent: Kanda Higashiyama Building, 2-1 Kanda Tamachi, Chiyoda-ku, Tokyo 101 Tel: 03 (254) 10396, Contents of amendment (1) Line 16 of page 9 of the specification "10Ω" r 1o11
Ω” I corrected. (2) On page 12, line 1, "in the symmetry zone" is corrected to "in the prohibited zone." (3) On page 16, line 4, "blocking so" is corrected to "blocking layer." (4) rB2Hs/SiH*10J on page 16, line 9
r B 2 Hs / S f H4:10-' J
I am corrected. (5) On page 17, line 3, "heat resistance system" is corrected to "heat resistance."that's all

Claims (5)

[Claims] (1) Group III or V of the periodic table on a conductive support
A blocking layer consisting mainly of microcrystalline silicon containing elements of group I as impurities and
An electrophotographic photoreceptor in which a photoconductive layer containing a Group II or Group V element as an impurity and consisting mainly of microcrystalline silicon is sequentially formed, wherein the blocking layer and/or the photoconductive layer is selected from group III of the periodic table. An electrophotographic photoreceptor characterized in that the concentration of a Group or Group V element changes in the film thickness direction and has a maximum concentration near the conductive support side. (2) The electrophotographic photoreceptor according to claim 1, wherein the blocking layer and/or the photoconductive layer is a mixture of microcrystalline silicon and amorphous silicon. (3) The electrophotographic photoreceptor according to claim 1, wherein the blocking layer and/or the photoconductive layer is a laminate of microcrystalline silicon and amorphous silicon. (4) The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein the microcrystalline silicon contains hydrogen atoms. (5) The electrophotographic photoreceptor according to any one of claims 1 to 4, wherein the uppermost layer has a surface layer different from the photoconductive layer.