JPS60235154A - Photosensitive body - Google Patents

Abstract

PURPOSE:To stabilize high acceptance potential and to obtain superior light fatigue resisting characteristics by forming an electrostatic charge blocking layer, a charge transfer layer, and a charge generating layer, each layer being of a specified a-Si type, and incorporating a specified element in the charge generating layer and a specified amt. of O in said blocking layer. CONSTITUTION:The charge blocking layer 44 made of a-SiN hydride or fluoride is arranged under the charge generating layer 43 made of a-Si hydride or fluoride, and an element of group IIIa is added to the layer 43 to form an intrinsic semiconductor by the glow discharge in a diborane/monosilane flow rate ratio of 1-100ppm. The layer 44 contains O in an amt. of 1-20atomic% of the total of Si+C+O, and further, N in an amt. of 30-70atomic%. A surface modifying layer 45 made of a-SiC or a-SiN hydride and/or fluoride contg. C or N in an amt. of 10-70atomic% is formed on the layer 43. The incorporation of O in the blocking layer 44 can enhance both of the charge blocking function and dark resistance, reduce its temp. dependence, and maintain acceptance potential good by forming the intrinsic charge generating layer 43.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Industrial Application Field The present invention relates to a photoreceptor, such as an electrophotographic photoreceptor.

2. Prior Art Conventionally, as an electrophotographic photoreceptor, Se or Ss is mixed with As,
%Te, Sb, etc. doped photoreceptor, ZnO'? C
Photoreceptors, etc. in which dS is dispersed in a resin binder are known. However, these photoreceptors are environmentally polluting and
There are problems with thermal stability and mechanical strength.On the other hand, electrophotographic photoreceptors using amorphous silicon (a-8L) as a matrix have been proposed in recent years.

a-8i has a so-called dangling bond in which the bond of 5t-8i is broken, and many localized levels exist within the energy gap due to this defect. For this reason, hopping conduction of thermally excited carriers occurs, resulting in a small dark resistance, and photoexcited carriers are trapped in localized levels, resulting in poor photoconductivity. Therefore, the dangling bonds are filled by compensating the defects with hydrogen atoms (H) and bonding 5ilCH.

Such amorphous hydrogenated silicon (hereinafter referred to as a-8
1: Referred to as H. ) has a resistivity in the dark of 10”~10@
Ω-cm, which is about 1 compared to amorphous Se.
It's even one millionth lower. Therefore, a photoreceptor made of a single layer of a-8i:H has problems in that the dark decay rate of the surface potential is high and the initial charging potential is low. However, on the other hand, when irradiated with light in the visible and infrared regions, the resistivity is greatly reduced, so it has extremely excellent characteristics as a photosensitive layer of a photoreceptor. ) r as heartwood and 1-daa-
An electrophotographic copying machine incorporating an 8i-based photoreceptor is shown. According to this copying machine, in the upper part of the cabinet 1,
A glass document mounting table 3 on which the document 2 is placed and a platen cover 4 that covers the document 2 are arranged. Below the document table 3, an optical scanning table consisting of a first mirror unit 7 equipped with a light source 5 and a first reflection mirror 6 is mounted 1 in the horizontal direction in the drawing.
The second mirror unit 20, which is provided so as to be movable along the u-line and is used to keep the optical path length between the document scanning point and the photoreceptor constant, moves in accordance with the speed of the first mirror unit, and the second mirror unit 20 moves in accordance with the speed of the first mirror unit, and The reflected light is made to enter a photosensitive drum 9 as an image carrier in a slit shape through a lens 21 and a reflecting mirror 8. Around the drum 9, a corona charger 101, a developing device 1, a transfer section 12, a separation section 13, and a cleaning section 14 are arranged (3), and each paper feed roller 16.
After the toner image is transferred from the drum 9, the copy paper 18 fed through the copy paper 17 is further fixed in a fixing section 19, and is discharged onto a tray 35. In the fixing section 19, the developed copy paper is passed between a heating roller 23 having a built-in heater 22 and a pressure roller 24 to perform a fixing operation.

However, photoreceptors with a-8i:H surfaces are susceptible to surface chemical stability, such as the effects of long-term exposure to the atmosphere or moisture, and the effects of chemical species generated by corona discharge. , has not been sufficiently investigated so far.

For example, items that have been left for more than a month will be affected by moisture.
It is known that the receptor potential is significantly reduced. on the other hand,
Amorphous hydrogenated silicon carbide (hereinafter referred to as a-8iC:
It is called H. ), its manufacturing method and existence are “Ph1
l.

Mag, Vol. 35'' (1978), etc., and its characteristics include high heat resistance and surface hardness, and a high dark resistivity (10'') compared to a-8t:H.
It is known that the optical energy gap (4) varies over a range of 1.6 to 2.8 eV depending on the amount of carbon. However, the inclusion of carbon widens the bandgap, resulting in poor long-wavelength sensitivity.

An electrophotographic photoreceptor combining such a-8iC:H and a-8i:H has been proposed, for example, in Japanese Patent Application Laid-Open No. 127083/1983. According to this, a-8t
:A functionally separated two-layer structure was created in which the H layer was used as a charge generation (photoconductive) layer, and the a-SiC:H layer was provided as a charge transport layer below this charge generation layer, and the upper layer a-8T:H It aims to obtain photosensitivity in a wider wavelength range and to improve the charging potential by the lower layer a-8tC:H forming a heterojunction with the a-8i:H layer.

However, the dark decay of the a-8t:I layer cannot be sufficiently prevented, and the charging potential is still insufficient to be of practical use.

On the other hand, JP-A-57-52178 discloses a-8i:
A first a-SiC:H layer is formed as a surface modification layer on the charge generation layer made of H, and a second a-SiC:H layer is formed on the back surface (support electrode side) as a charge blocking layer. are doing.

However, in known photoreceptors, especially a-8IC
:II″rJ! It has been found that the load blocking layer has the following problems.

That is, in the known a-8iC:H, the temperature value of the dark resistance ρ is large, and therefore the charging potential retention characteristic deteriorates at high temperatures, making it unusable for practical use, and image blurring is also likely to occur. These defects also occur when the charge blocking layer is formed of known amorphous silicon nitride (a-8IN).

3. OBJECTS OF THE INVENTION An object of the present invention is to provide a photoreceptor that can stably maintain a high charging potential (particularly under high temperature or high humidity) and has excellent optical fatigue properties.

4. Structure of the invention and its effects, that is, the photoreceptor according to the invention has a charge blocking layer made of amorphous hydrogenated and/or fluorinated silicon nitride under a charge generation layer made of amorphous hydrogenated and/or fluorinated silicon. In the photoreceptor, the charge generation layer is made intrinsic by containing an element of group Ⅰa of the periodic table, and the charge blocking layer contains 1 to 1.
20 atomic oxygen (however, the total number of silicon atoms, nitrogen atoms, and oxygen atoms is 100 atomic
%. ).

According to the present invention, it is a functionally separated photoreceptor, and the charge blocking layer thereof contains 1 to 20 atomic q6 of oxygen, so that while exhibiting charge blocking ability, ρ1. effectively increasing ρ.

The temperature dependence (dρ, /dT) of can be kept small. Therefore, the charging potential retention characteristics are improved, and the upper limit temperature (and the upper limit humidity) at which the photoreceptor can be used can be increased. If the above oxygen content is 1 a
If it is less than atomic %, the effect of oxygen content will not be exhibited, and if it exceeds 20 atomic %, there will be too much oxygen, and carrier mobility, that is, (μτ), will be significantly reduced. Therefore, the oxygen content should be reduced from 1 to 20 at
It is essential to set it to omic%, especially 5
It is desirable to set it to 15 atomlc%. Furthermore, since the charge generation layer is made intrinsic by containing the elements of group [11'a] of the periodic table (7), it has a high resistance (specific resistance of 10'' to 10'' Ω-cm), which reduces the charging of the photoreceptor. Contributes to maintaining good potential.

5. Examples Hereinafter, the present invention will be described in detail with reference to examples.

FIG. 2 shows an A-8L electrophotographic photoreceptor 39 according to this embodiment.
This shows that. This photoreceptor 39 is arranged on a drum-shaped conductive support substrate 41 such as A1, and is provided with 1 to 20 atoms of oxygen.
a charge blocking layer 44 made of a-8iN:H containing ic%; and an l-type (X-characterized) charge generation layer made of a-8i:H doped with an Ha group element of the periodic table, such as boron. 43, and amorphous hydrogenated carbide or silicon nitride (a-8iC:H
or a-SIN:H) or a surface modification layer 45 made of an inorganic substance such as SiO*. The charge generation layer 43 has a ratio of resistivity ρ in the dark and resistivity ρ during light irradiation that is sufficiently large for an electrophotographic photoreceptor and has photosensitivity (particularly to light in the visible and infrared regions).
is good.

(8) In addition, the periodic table [Ma group elements, such as boron]
By doping with B, H, /SiH, )-1 to 100p +
0゛~10゛Ω-cm)L, high resistance can be achieved.

In this photoreceptor 39, there is a trench, based on the present invention, a-
Oxygen atoms are added to the charge blocking layer 44 made of 8iN:H at a total number of St -1-N -1-0 atoms of 1.00 at
The content is 1 to 20 atomic% based on the omic.

With this content range of oxygen, the charge blocking layer 4
The ρ of 2 is high even under high temperature (or high humidity), and the charging potential holding ability of the photoreceptor is stably maintained.The nitrogen atom content of the charge blocking layer 44 is 30 to 70.
atomic % (total number of atoms of St -1-H is 1
00 atomic. ) is preferable,
Still, it is appropriate that the film thickness be 400 to 4000 A.

Further, regarding the thickness of each layer described above, the charge generation layer 42
is 10 to 30 μm 1 Blocking layer 44 is 400A to 4
It is better to set it to 000 A. Charge generation layer 43 has a thickness of 10μ
If it is less than m, the charging potential will not be sufficient, and if it exceeds 30 μm, it is still insufficient for practical purposes. Blocking layer 4
When 4 is less than 400 A, the blocking effect is weak, and when it exceeds 4000 A, the charge transport ability tends to be poor.

The surface-modified layer 45 is formed by modifying the surface of the photoreceptor.
It is preferable to provide this in order to make the photoreceptor of the system practically superior. That is, it enables the basic operations of an electrophotographic photoreceptor, such as charge retention on the surface and attenuation of the surface potential due to light irradiation.

Therefore, the repetitive characteristics of charging and optical attenuation become very stable, and good potential characteristics can be reproduced even if left for a long period of time (for example, one month or more). In the case of a photoreceptor having a-8i:H as a surface, it is easily affected by humidity, air, ozone atmosphere, etc., and the potential characteristics tend to change over time. In addition, since the surface modified layer 45 made of a-8iC:H or a-8iN:H has high surface hardness, it has abrasion resistance in processes such as development, transfer, and cleaning, and also has good heat resistance. Processes that apply heat, such as adhesive transfer, can be applied.

In order to achieve such excellent effects comprehensively, a-
It is important to select the carbon or nitrogen composition of 8iC: H or a-SiN: I (i.e., when the carbon or nitrogen atom content reaches 5i-1-C (or N)-100 Desirably, it is 70 atomic %. When the C or N content is 10% or more, the above-mentioned sheath resistivity becomes the desired value, and the optical energy gap becomes approximately 2.0eV or more, and the visible and infrared Due to the so-called optically transparent window effect, the irradiated light is a-
8t: It becomes easier to reach the H layer (charge generation layer) 43. However, if the number of C or N-containing needles is less than 10 inches, the specific resistance will be less than a desired value, and a portion of the light will be absorbed by the surface layer 45, making it easy for the photosensitivity of the photoreceptor to decrease. Also, C
Alternatively, if the N content exceeds 70%, the amount of carbon or nitrogen in the layer increases, and the semiconductor properties are likely to be lost.
C:H film or a-8iN: Since the deposition rate when forming the H film by the glow discharge method tends to decrease, the C or N content is preferably 70 or less.

In addition, the (11) film thickness of the a-8iC:H or a-8iN:H layer 45 is within the range of 40OA≦t≦500OA (especially 400OA
It is also important to select A≦t<2000 A).

That is, if the film thickness exceeds 500OA, the residual potential (8) becomes too high and the photosensitivity decreases, resulting in a-8
It does not easily lose its good characteristics as an l-based photoreceptor.

Furthermore, if the film thickness is less than 400 Å, charges will no longer be charged on the surface due to the tunnel effect, resulting in an increase in dark decay and a decrease in photosensitivity.

Note that each of the above layers needs to contain hydrogen.

In particular, the hydrogen content in the charge generation layer 43 is essential for compensating for dangling bonds and improving photoconductivity and charge retention, and is in the range of 10 to 30 atoms.
It is desirable that it is c%.

This content range includes the surface modification layer 45 and the blocking layer 44.
The same is true. In addition to boron, A/ may be used as a doping impurity for the charge generation layer 43.

Group ff1a elements of the periodic table, such as GaXIn and T1, can be used.

Next, a method for manufacturing (12) the above-mentioned photoreceptor (for example, drum-shaped) and its apparatus (glow discharge device) will be explained with reference to FIG.

Inside the vacuum chamber 52 of this device 51, a drum-shaped substrate 41
is set so as to be vertically rotatable, and the substrate 4 is heated by a heater 55.
1 can be heated to a predetermined temperature from the inside.

A cylindrical high frequency electrode 57 with a gas outlet 53 is disposed around and facing the substrate 41, and a glow discharge is generated between the electrode 57 and the substrate 41 by a high frequency power source 56. In addition, 62 in the figure is a supply source of S i Ha or a gaseous silicon compound, 63 is a supply source of O3 or a gaseous oxygen compound, and 64 is a CII.

65 is a carrier gas supply source such as Ar, 66 is an impurity gas (B, H, etc.) supply source, and 67 is each flow meter. . In this glow discharge device, first, the surface of a support, for example, A/substrate 41 is cleaned, and then placed in a vacuum chamber 52, and the gas pressure in the vacuum chamber 52 is set to 10-@To.
The substrate 41 is heated to a predetermined temperature, particularly 100 to 350°C (preferably 150 to 30°C).
Heat and maintain at 0℃). Then, using a high purity inert gas as a carrier gas, S i Ha or a gaseous silicon compound, B,:E(,,CH).

(or NU,,N, ), 0. is appropriately introduced into the vacuum chamber 52, and a high frequency voltage (for example, 13.56 M
Hz) is applied. As a result, each of the above reaction gases is decomposed by glow discharge between the electrode 57 and the substrate 41, and 0-containing a-SiN:H, boron-doped aSl:H
%a-8iC:H or IL-8IN:H above layer 4
4.43.45 on the substrate sequentially (ie, in response to the example of FIG. 2).

In the above manufacturing method, the support temperature is set at 100 to 350°C in the step of forming the a-8t layer on the support, so the film quality (especially electrical properties) of the photoreceptor can be improved. .

In addition, when forming each layer of the above a-81 series photoreceptor,
In order to compensate for dangling bonds, fluorine is introduced in the form of SiF, etc. in place of the above H or in combination with H, and a-8i: F, a-8t: H: F, a
-8iN:F, a-8iN:I(:F, a -8i
C: F, a-8iC: H: F can also be used.

In this case, the amount of fluorine is preferably 15 to 10 atomic%.

The above manufacturing method is based on the glow discharge decomposition method, but there are also methods such as sputtering method, ion blating method, and method of evaporating St while introducing activated or ionized hydrogen in a hydrogen discharge tube. ←In particular, Japanese Patent Application Laid-open No. 56-78413 (Japanese Patent Application No. 152-1983) filed by the present applicant
The above photoreceptor can also be manufactured by the method of No. 455).

FIG. 4 shows a photoreceptor according to the present invention in the above-mentioned Japanese Patent Application Laid-Open No. 56-78.
413 shows a vapor deposition apparatus used for fabrication by the vapor deposition method of No. 413.

The Pel jar 71 is connected to a vacuum pump (not shown) via an exhaust pipe 73 having a butterfly valve 72, thereby pumping the inside of the Pel jar 71, for example, from 10 to 10.
-'TorrO high vacuum state. The Pelger 7
A substrate 41 is placed inside the substrate 1 and heated to a temperature of 100 to 350°C, preferably 150 to 300°C by a heater 75, and a DC power source 76 (15) applies a voltage of 0 to -10 kV to the substrate 1, preferably. -1~-6k
A negative DC voltage of V is applied. a-8t: To form the H layer 43, active hydrogen and hydrogen ions are introduced into the Pel jar 71 from a hydrogen gas discharge tube 77 connected to the Pel jar 71 so that its outlet faces the substrate 41.
To form the 0a-8iC:H layer 45, the silicon evaporation source 78 and the aluminum evaporation source 79 provided to face the substrate 41 are heated and the upper shutter S is opened.
Evaporate the silicon under the supply of CI (,
The charge blocking layer 44 may be formed by evaporating silicon 78 while supplying NH instead of CH, or even at 0°.

CH, NH, and Ot may be activated and introduced as appropriate via the discharge tube 7o.

The structure of the discharge tube 77, 70 is shown for example in the case of the discharge tube 77, as shown in FIG. , a discharge space member 84 made of, for example, cylindrical glass, surrounding a discharge space 83, and a ring-shaped other electrode member 86 provided at the other end of the discharge space member 84 and having an outlet 85 (16). By applying a DC or AC voltage between the one electrode member 82 and the other electrode member 86, for example, hydrogen gas supplied via the gas port 81 causes a glow discharge in the discharge space 83. As a result, active hydrogen consisting of hydrogen atoms or molecules activated by electron energy and ionized hydrogen ions are discharged from the outlet 85.
The discharge space member 82 in this illustrated example has a double pipe structure and is configured to allow cooling water to flow therethrough, and reference numerals 87 and 88 indicate a cooling water inlet and an outlet. 89 is a cooling fin for one electrode member 82. The distance between the electrodes in the hydrogen gas discharge tube 77 is 10 to 15 cm, and the applied voltage is 6 cm.
00■, the pressure in the discharge space 83 is about 10-'' Torr.

Hereinafter, the present invention will be described with reference to specific examples. By the O glow discharge decomposition method, a second
An electrophotographic photoreceptor having the structure shown in the figure was manufactured.

That is, first, after cleaning the surface of a support, for example, a drum-shaped Al substrate 41 having a smooth surface, it is placed in a vacuum chamber 52 in FIG. 3, and the gas pressure in the vacuum chamber 52 is set to 10"-
"Torr" and exhaust the air, and the substrate 41
at a predetermined temperature, especially 100 to 350°C (preferably 150°C)
-300°C). Next, high purity Ar
A gas was introduced as a carrier gas, a high frequency power of 13.56 MHz was applied under a back pressure of 0.5 Torr, and preliminary discharge was performed for 10 minutes. Then, SiH
4 and NH, and 0. A reaction gas consisting of
:1:6:1 (Ar +SiH, -1-NH, +O
,) By decomposing the mixed gas by glow discharge, a blocking layer 44 having a zero-containing charge blocking function is formed. Subsequently, the supply of NH,,0, is stopped and B, H,
The SiH4 is decomposed by discharge without introducing
-8L: H layer 43 was formed. Subsequently, the flow rate ratio 4
: Glow discharge decomposition with a 1:6 (Ar + stu, + c■, ) mixed gas to form a-8iC:H of a predetermined thickness.
A surface protective layer 45 was further provided to complete the electrophotographic photoreceptor. Using this photoreceptor, a copying machine (U-Bix 30
00 modified machine (manufactured by Konishiroku Photo Industry Co., Ltd.), a clear image with good resolution and gradation, high image density, and no fog was obtained. Also, 20
Stable, high-quality images were continuously obtained even after repeated copying 10,000 times.

That is, during the test, the electrophotographic photoreceptor prepared as described above was attached to an electrometer model 5P-428 (manufactured by Kawaguchi Electric Co., Ltd.), and the voltage applied to the discharge electrode of the charger was set to + or -6 kV. , perform a charging operation for 10 seconds, set the charged potential of the photoreceptor surface immediately after this charging operation to Vo (V ), and after dark decay for 2 seconds, reduce the amount of irradiation light necessary to attenuate the charged potential to 1/2. The exposure ILE was set to 1/2 (1 uxe sec). The light attenuation curve of the surface potential becomes flat at a certain finite potential,
Although it may not become completely zero, this potential is called a residual potential V; (V).

By varying the composition of each layer, the results shown in the table below were obtained. According to this, O of the charge blocking layer
It is found that when the content is 1 to 20 atomic % and the charge generation layer (19) is made intrinsic by doping with B, the electrophotographic properties of the photoreceptor are greatly improved and the temperature dependence is reduced. Regarding the image quality, ◎ indicates that the image is clear, ◯ indicates that the image is good, Δ indicates that the image quality can be practically adopted, and × indicates that the image quality cannot be practically adopted.

(Margin below, continued on next page) (20)

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a conventional electrophotographic copying machine. 2 to 5 show examples of the present invention, in which FIG. 2 is a sectional view of an a-8i photoreceptor, FIG. 3 is a schematic sectional view of a glow discharge device, and FIG. 4 is a schematic sectional view of a glow discharge device. A schematic cross-sectional view of the vacuum evaporation apparatus d, and FIG. 5 is a cross-sectional view of the gas discharge tube. In addition, in the symbols shown in the drawings, 39......A-8i type photoreceptor 41...・・・・Support body (substrate) 43 ・・・・・・・・・・・・・・・・・・
Charge generation layer 44・・・・・・・・・・・・・・・
Charge blocking layer 45・・・・・・・・・・・・・・・
...Surface modified layer 55...
・・・Heater 56・・・・・・・・・・・・・・・
・−・High frequency power supply 57・・・・・・・・・・・・・・・
...Electrodes 62 to 66......Each gas supply source 70.77......Gas discharge tube 78.79.
・・・・・・・・・It is a source of evaporation. Agent Patent Attorney Hiroshi Aisaka

Claims (1)

[Scope of Claims] 1. A photoreceptor in which a charge blocking layer made of amorphous hydrogenated and/or fluorinated silicon nitride is provided under a charge generation layer made of amorphous hydrogenated and/or fluorinated silicon, The charge generation layer is made intrinsic by containing an element of group 1 [a] of the periodic table, and the charge blocking layer contains 1 to 20 atomic%.
(However, the total number of atoms of silicon atoms, nitrogen atoms, and oxygen atoms is 100100 ato %.). 2. The charge generation layer is formed by glow discharge decomposition under conditions where diborane and monosilane are supplied at a flow rate ratio of 1 to 100 P of diporane/monosilane.
A photoreceptor according to claim 1. 3.Charge block LFF7K/G layer is 30-70 atoms
The patent is characterized by fluorinated carbide (or nitride) silicon and has a carbon or nitrogen content of 10 to 70 atomic chi (however,
The total number of silicon atoms and carbon or nitrogen atoms is 10.
It is set to 0 atomic%. ) The photoreceptor according to any one of claims 1 to 3, wherein the photoreceptor is provided with a surface-modified layer.