JPS60235156A - Photosensitive body - Google Patents

Abstract

PURPOSE:To stabilize high acceptance potential and to botain 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, on a substrate in succession, and incorporating a specified amt. of O in said blocking layer, and an element of group IIIa in the charge transfer layer. CONSTITUTION:The charge blocking layer 44 made of a-SiN, the charge transfer layer 42 made of a-SiC and/or a-SiN, and the charge generating layer 43 made of a-Si, Si of each layer hydrogenated and/or fluorinated, are formed on the substrate 41 in this order from its side. The layer 42 is a little doped with an element of group IIIa by the glow discharge in a flow ratio of diborane/monosilane of 1-20ppm and the layer 44 contains O in an amt. of 1-20atomic% of Si+C+O, and further, N in an amt. of 30-70atomic%. The layer 42 contains C or N in an amt. of 10-30atomic%. A surface modifying layer 45 made of hydrogenated and/or fluorinated a-SiC or the like contg. C in an amt. of 10-70atomic% is formed on the layer 43. The use of such a structure enhances dark resistance, in spite of having charge blocking ability by the action of the layer 44, and lowers its temp. dependence, and improves injection of carriers from the layer 43 to the layer 42 by forming the intrinsic charge transfer layer 42.

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 (2) Conventionally, as an electrophotographic photoreceptor, Se, or Se and As,
Photoreceptors doped with Te, Sb, etc., photoreceptors in which ZnO or CdS is dispersed in a resin binder, and the like are known. However, these photoreceptors have problems in terms of environmental pollution, thermal stability, and mechanical strength.

It is being proposed. a-3i has a so-called dangling bond in which the bond of 5i-3i 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 H to Si.

Such amorphous hydrogenated silicon (hereinafter referred to as a-3
It is called i:H. ) has a resistivity of 10g to 109 in the dark.
It is marked Ω-, which is about 1/10,000 times lower than that of amorphous Se. Therefore, a photoreceptor made of a single layer of a-3i: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 properties as a photosensitive layer of a photoreceptor.

Figure 1 shows a-3 with the above a-3i:) (as the base material).
An electrophotographic copying machine incorporating an i-system photoreceptor is shown.

According to this copying machine, a glass document mounting table 3 on which a document 2 is placed and a platen cover 4 that covers the document 2 are arranged at the top of a cabinet 1. 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 provided so as to be movable in a straight line in the left and right direction of the drawing. The second mirror unit 2o moves in accordance with the speed of the first mirror unit to keep the optical path length constant, and the reflected light from the document table 3 passes through the lens 21 and the reflection mirror 8, and is reflected as an image carrier. The light is incident on the photoreceptor drum 9 in a lit pattern (3). A corona charger 10, a developer 11, a transfer section 12, a separation section 13, and a cleaning section 14 are arranged around the drum 9, respectively.
Copy paper 18 fed from paper feed box 15 via paper feed rollers 16 and 17 is further fixed in fixing section 19 after the toner image is transferred from drum 9, and then ejected to tray 35. Fusing part I
9, the developed body is placed between a heating roller 23 with a built-in heater 22 and a pressure roller 24 due to the effects of long-term exposure to the atmosphere and moisture, and the effects of chemical species generated by corona discharge. Up to now, sufficient studies have not been made regarding the chemical stability of surfaces such as those mentioned above. For example, it is known that if a device is left for more than a month, it will be affected by moisture and its acceptance potential will drop significantly. On the other hand, amorphous hydrogenated silicon carbide (hereinafter referred to as a-3iC:H).

), its manufacturing method and existence are Ph1l, Mag.

Vol. 35'' (1978), etc., and its characteristics include high heat resistance and surface hardness, and a-3i
:1((5) High dark resistivity (1d' to 1Ω-cln) compared to (4)
It is known that the optical energy gap changes over a range of 1.6 to 2.8 eV depending on the carbon content. However, there is a drawback that the long wavelength sensitivity becomes poor because the hand gap widens due to the inclusion of carbon.

An electrophotographic photoreceptor combining such a-8IC:H and a-5i:H has been proposed, for example, in Japanese Patent Laid-Open No. 127083/1983. According to this, a-3t:H
The layer is a charge generation (photoconductive) layer, and below this charge generation layer is a
A functionally separated 2N structure was created in which the -S i Cr H layer was provided as an N transport layer, and the upper layer a-31:H provided photosensitivity in a wide wavelength range, and the a-3i:Hliii
The lower layer a-S i C forming a heterojunction with: H
This aims to improve the charging potential. However, a
-3i: The dark decay of HN cannot be sufficiently prevented, and the charging potential is still insufficient to be of practical use.

On the other hand, in JP-A-57-17952 and JP-A-57-52178, a first (
6) The a-3i Cs H layer is formed as a surface modification layer, and the second a-3iC:H layer is formed on the back surface (support electrode side) as a charge transport layer or a charge blocking layer.

However, in known photoreceptors, a-3iC:
It has been found that the H charge blocking layer has the following problems.

That is, the well-known a S i C: H is dark resistance ρ. has a large temperature dependence, and as a result, the charging potential retention characteristics deteriorate at high temperatures, making it unusable for practical use, and image deletion is likely to occur. These defects also occur when the charge blocking layer is formed of known amorphous silicon nitride (a-3iN).

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 present invention has an amorphous hydrogenated and/or fluorinated carbide (and/or nitrided) layer under a charge generation layer made of amorphous hydrogenated and/or fluorinated silicon. In a photoreceptor in which a charge transport layer made of silicon is provided, and a charge blocking layer made of amorphous hydrogenated and/or fluorinated silicon nitride is provided below the charge transport layer, the charge transport layer is formed in the periodic table. 1st n
The charge blocking layer contains a relatively small amount of Group A elements, and the charge blocking layer contains 1 to 20 atomic% oxygen (provided that the total number of silicon atoms, nitrogen atoms, and oxygen atoms is 10010
It is set to 0ato%. ).

According to the present invention, it is a functionally separated photoreceptor, and the charge blocking layer contains 1 to 20 atomic% of oxygen, so that the charge blocking ability can be exhibited while effectively increasing ^. temperature dependence (dq/
dT) can be kept small. Therefore, the charging potential retention characteristics are improved, and the upper limit temperature (the upper limit temperature) at which the photoreceptor can be used can also be increased. If the above oxygen content is l
If it is less than atomic%, it is due to oxygen content ('t
) The effect is not exhibited, and if it exceeds 20 atomic %, there is too much oxygen, and the carrier mobility, that is, (μτ), decreases significantly. Therefore, the oxygen content should be 1 to 20
It is essential to set it to atomic%, and it is particularly desirable to set it to 5 to 15 atomic%. Furthermore,
Since the charge transport layer contains a relatively small amount of the group Ma element of the periodic table (lightly doped), it contributes to good injection of carriers from the charge generation layer to the charge transport layer. .

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

FIG. 2 shows an a-3i electrophotographic photoreceptor 39 according to this embodiment.
This shows that. This photoreceptor 39 is made of a drum-shaped conductive support substrate 41 made of Aβ, etc.
A charge blocking layer 44 consisting of ly a -S i N :H containing ly a -S i
-3iN:H charge transport layer 42 and a-3t:H
A charge generating N43 consisting of N43 and an inorganic material such as amorphous hydrogenated carbide or nitride (9) (8) silicon (a-3iC:H or a-3iN:H) or SiOa, which is provided as necessary. The surface modification layer 45 has a laminated structure. The charge generation layer 43 has a dark resistivity ρ. The ratio of resistivity to resistivity upon irradiation with light is sufficiently large as an electrophotographic photoreceptor, and the photosensitivity (particularly to light in the visible and infrared regions) is good.

In this photoreceptor 39, based on the present invention, a-3i
Oxygen atoms are added to the charge blocking layer 44 made of N:H.
1 to 100100ato% of the total number of atoms of i1N+0
It contains 20 atomic%. With this content range of oxygen, the ρ of the charge blocking layer 42. becomes high even at high temperatures (or high/!ii), and the ability to hold the charged potential as a 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+H is 100100a
to%. ), and the film thickness is suitable for 400 to 4000 people.

Further, the charge transport layer 42 includes elements of Group Ma of the periodic table,
For example, boron has a flow rate ratio of B2H6/S i Hq=
Lightly doped by glow discharge decomposition at 1-20 pPm (10). The carbon or nitrogen content of this charge transport layer is 10
~30 atomic% (the total number of atoms of Si+C (or N) is 100100 atomic%) is desirable.

Regarding the thickness of each layer described above, charge generation N42 is 1 to
5μm, Flocking N44: 400 to 4000
If the temperature is too high, the residual potential will increase, which is insufficient for practical use. Pro 7
If the number of layers in the king layer 44 is less than 400, the locking effect will be weak, and if it exceeds 1,0001, the charge transport ability will tend to be poor. Charge transport [42] is preferably 10 to 30 μm.

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-3t:H on its surface, it is easily affected by humidity, air, ozone atmosphere, etc., and potential characteristics tend to change over time. Also, a
The surface modification layer 45 made of -3iC:H or a-S i N :H can be used in a heat application process such as adhesive transfer due to its surface hardness.

In order to achieve such excellent effects comprehensively, a-
It is important to choose the carbon or nitrogen composition of 3iC:H or a-3iN:H. That is, the carbon or nitrogen atom content is 10 to 7 when Si + C (or N) = 100%.
It is desirable that it be 0 atomic%. When the C or N content is 10% or more, the above-mentioned specific resistance becomes the desired value, and the optical energy gear becomes approximately 2.0%. QeV
As described above, due to the so-called optically transparent window effect for visible and infrared light, the irradiated light a-3i:H layer (charge generation N)
It becomes easier to reach 43. However, the C or N content is 10
If it is less than %, the specific resistance tends to be less than a desired value, and part of the light is absorbed by the surface N45, and the photosensitivity of the photoreceptor tends to decrease. Furthermore, if the C or N content exceeds 70%, the amount of carbon or nitrogen in the layer increases, and semiconductor properties are likely to be lost. Since the deposition rate tends to decrease when
Alternatively, the N content is preferably 70% or less.

Also, a-S i C: H or a-S i N
: It is also important to select the membrane weight of HH45 within the range of 400 people≦t≦5000 people (particularly 400 people≦t<2000 people). That is, if the film thickness exceeds 5000 K, the residual type VFT becomes too high and the photosensitivity decreases, resulting in a-
The good characteristics of a 3i photoreceptor are not likely to be lost. Also,
If the film thickness is less than 400 nm, the tunnel effect prevents charges from being charged on the surface, resulting in an increase in dark decay and a decrease in photosensitivity.

Note that each layer in -1- 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.
Desirably, it is 30 atomic%. This content range also applies to the surface modification layer 45, blocking N44, and charge transporting M42. In addition to boron, A7! is also used as a doping impurity for charge transport N42! , Ga, In
, TA, and other group Ma elements of the periodic table can be used.

Next, a method for manufacturing the above-mentioned photoreceptor (for example, drum-shaped) and an apparatus therefor (glow discharge apparatus) 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,
In the figure, 62 is a source of SiH4 or a gaseous silicon compound, 63 is a source of 02 or a gaseous oxygen compound, 64
65 is a carrier gas supply source such as Ar (14), 66 is an impurity gas (for example
3.Hb) supply source, 67 is each flow meter. In this glow discharge device, first, a support such as an Aβ substrate 4 is used.
After cleaning the surface of the substrate 1, the substrate 41 is placed in a vacuum chamber 52, the gas pressure in the vacuum chamber 52 is adjusted to 10 Torr, and the gas pressure is evacuated.
Heat and maintain at ~350°C (preferably 150-300°C). Then, S i T (or gaseous silicon compound, B
zHb, CH (or N H, t N, ), 02 are appropriately introduced into the vacuum chamber 52, for example, at a pressure of 0.01 to 10 Torr.
A high frequency voltage (for example, 13.56 MHz> is applied by the high frequency power supply 56 under a reaction pressure of r. By this, "
The double reaction gases are decomposed by glow discharge between the electrode 57 and the substrate 41 to form a 0-containing a-3iN:H, boron light-doped a-SiN:H or a-3iN:HXa-
3t:H, a-3iC:H or a-S i N:
I-T is deposited successively (i.e. corresponding to the example of FIG. 2) on the substrate as layers 44, 42, 43, 45 described above.

In the above manufacturing method, the support temperature is set at 100 to 350°C in the step of forming the a-3t layer on the support, so it is possible to improve the film quality (especially the electrical properties) of the photoreceptor. can.

In addition, in order to compensate for dangling bonds when forming each layer of the a-3i photoreceptor, fluorine is introduced in the form of SiF4 or the like instead of the above-mentioned H or in combination with H. , a-3i :F, a-3i :H:F, a-3i
N:F, a-3iN:H:F, a-3iC:F.

It can also be a-3iC:l(:F. In this case, the amount of fluorine is preferably 0.5 to 10 atomic%.

The above manufacturing method is based on the glow discharge decomposition method, but other methods include sputtering method, ion blating method, and method of evaporating Si while introducing activated or ionized hydrogen in a hydrogen discharge tube. (In particular, Japanese Patent Application Laid-Open No. 56-78413 (Patent Application No. 54-15) filed by the present applicant)
The above photoreceptor can also be manufactured by the method of No. 2455).

FIG. 4 shows a photoreceptor according to the present invention in the above-mentioned Japanese Patent Application Laid-Open No. 56-7'.
This figure shows a vapor deposition apparatus used for fabrication by the vapor deposition method of No. 8413.

(The 10 tor jar 71 is connected to a vacuum pump (not shown) through an exhaust pipe 73 having a butterfly valve 72, thereby controlling the inside of the pell jar 71 to a temperature of 10 to 0 Torr, for example.
A high vacuum state of r is established. A substrate 41 is placed inside the Pelger 71 and heated to a temperature of 100 to 100°C by a heater 75.
While heating to 350° C., preferably 150 to 300° C., a DC power source 76 applies 0 to -10 kV to the substrate 1.

Preferably, a negative DC voltage of -1 to -6 kV is applied.

a-3i: To form HJi 43, active hydrogen and hydrogen ions are introduced into Pel Jar 71 from a hydrogen gas discharge tube 77 connected to Pel Jar 71 so that the outlet faces the substrate 41, and the substrate is heated. A silicon evaporation source 78 provided opposite to the silicon evaporation source 78 is heated, and the upper shutter S is opened. a-3i C: To form H1!45, silicon is evaporated under CI (θ supply. Also, the charge blocking 1f44 is performed using N H instead of CH4.
3. The silicon 78 may be evaporated while being supplied to . a-S i C: H layer 42 has A7 instead of ○λ
! It can be formed by evaporating and supplying 79. C
H,, NH3,0 U is activated (17
) (16) and introduce it as appropriate.

For example, the structure of the discharge tube 77, 70 is shown in FIG. 5, as shown in FIG. , a discharge space member 84 made of, for example, cylindrical glass surrounding the discharge space 83, and another ring-shaped electrode member 86 having an outlet 85 provided at the other end of the discharge space member 84.
By applying a DC or AC voltage between the one electrode member 82 and the other electrode member 86, hydrogen gas, for example, supplied via the gas port 81 glows in the discharge space 83. A discharge occurs, whereby active hydrogen consisting of hydrogen atoms or molecules activated by electron energy and ionized hydrogen ions are discharged from the outlet 85.
more excreted. The discharge space member 82 in this illustrated example has a double pipe structure and is configured to allow cooling water to flow through it.
87 and 88 indicate the cooling water inlet and outlet. 89 is a cooling fin for one electrode member 82. The electrode tube distance in the hydrogen gas discharge tube 77 between the above is 10 to 15
cm, the applied voltage is 600 V, and the pressure in the discharge space 83 is approximately (18) 10 Torr.

Hereinafter, the present invention will be described with reference to specific examples.

An electrophotographic photoreceptor having the structure shown in FIG. 2 was prepared on a drum-shaped A6 support by a glow discharge decomposition method.

That is, first, after cleaning the surface of a support, for example, a tram-shaped Aβ substrate 41 having a smooth surface, it is placed in a vacuum chamber 52 shown in FIG.
The substrate 41 is heated to a predetermined temperature, particularly 100 to 350°C (preferably 150 to 300°C).
Heat and maintain at ℃). Next, high-purity Ar gas was introduced as a carrier gas, and high-frequency power with a frequency of 13.56 MH□ was applied under a back pressure of 0.5 Torr.
A preliminary discharge was performed for 1 minute. Then, S i H4 and N
Hl and 0. A reaction gas consisting of was introduced, and the flow rate ratio was 4:1:
6:, C1) of (A r + S i H40N
H9+○,) continued, A/ Ih, B, Hl,, 0. The supply of S]1(+ was stopped, and S]1(+ was decomposed by discharge to form an a-3i:8 layer 43 of a predetermined thickness.Subsequently, a flow rate ratio of 4
:1:6 (Ar+SiH.

+CI(,) mixed gas was decomposed by douglow discharge, and a predetermined thickness of a-3iC:8 surface protection N45 was further provided to complete the electrophotographic photoreceptor. Using this photoreceptor, a copying machine (U-B i x3000 modified machine: Konishiroku Photo Industry [
As a result, a clear image with good resolution and gradation, high image density, and no fog was obtained. Also, even after repeated copying 200,000 times,
Stable, high-quality images were continuously obtained.

That is, during the test, the electrophotographic photoreceptor prepared as described above was attached to an electrometer model 5P-428 (manufactured by Kawaguchi Electric), and the voltage applied to the discharge electrode of the charger was set to +6 kV for 10 seconds. A charging operation is performed, and the charged potential of the photoreceptor surface immediately after this charging operation is Vo (V
), and after +'+Ff decay for 2 seconds, the charging potential is reduced to 1/2.
Exposure amount F3 to reduce the amount of irradiation light required to attenuate by half
．． 1. / 2 (Iu ・see) (1 Soft) The light attenuation curve of the surface potential becomes flat at a certain finite potential and may not become completely zero, but this potential is called the residual potential VR (V ). .

By varying the composition of each layer, the results shown in the table below were obtained. According to this, it can be seen that when the zero content of the charge blocking layer is set to 1 to 20 atomic %, 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.) (21) (20)

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a conventional electrophotographic copying machine. Figures 2 to 5 show embodiments of the present invention, in which Figure 2 is a cross-sectional view of an a-3i-based ill-sensitivity light, Figure 3 is a schematic cross-sectional view of a glow discharge device, and Figure 4 is a schematic cross-sectional view of a glow discharge device. A schematic cross-sectional view of the vacuum evaporation apparatus, and FIG. 5 is a cross-sectional view of the gas discharge tube. In addition, in the symbols shown in the drawings, 39.
...a-3ii photoconductor 41 ......
・・・・・・・・・・・・・・・Support (substrate) 42
・・・・・・・・・・・・・・・・・・・・・・・・
・・Charge transport layer 43・・・・・・・・・・・・・・・・
......Charge generation layer 44...
・・・・・・・・・・・・・・・・・・Charge blocking layer 45・・・・・・・・・・・・・・・・・・
......Surface modified layer 55...
・・・・・・・・・・・・・・・・・・Heater 56...
・・・・・・・・・・・・・・・・・・・・・・・・
High frequency power supply 57・・・・・・・・・・・・・・・・・・
...... Electrode (23) 62-66...
・Each gas supply source 70.71・・・・・・・・・・・・・
......Gas discharge tube 78...
・・・・・・・・・・・・・・・・・・It is a source of evaporation. Agent Patent Attorney Hiroshi Aisaka (24) ) LL-1 (n ~ %) - Deaf ) ) S# Deaf

Claims (1)

[Claims] 1. A charge transport layer made of amorphous hydrogenated and/or fluorinated silicon carbide (and/or nitride) is provided under a charge generation layer made of amorphous hydrogenated and/or fluorinated silicon, In a photoreceptor in which a charge blocking layer made of amorphous hydrogenated and/or fluorinated silicon nitride is provided under this charge transport layer, the charge transport layer (the total number of atoms of silicon atoms, nitrogen atoms, and oxygen atoms) (However, the total number of atoms of silicon atoms and carbon or nitrogen atoms is 100100 atomic%.), and (1) diborane and monosilane are diborane/ Monosilane-1~
A photoreceptor according to claim 1, which is formed by glow discharge decomposition under conditions of supply at a flow rate of 20 ppm. 3. The charge blocking layer contains 30 to 70 atomic% nitrogen (however, the total number of silicon atoms and nitrogen atoms is I
Q□atomic%. ) The photoreceptor according to claim 1 or 2, characterized in that: 4. On the charge generation layer, the charge generation layer is made of amorphous hydrogenated and/or fluorinated carbide (or nitride) silicon and has a carbon or nitrogen content of 10 to 70 atomic% (however, the total atomic amount of silicon atoms and carbon or nitrogen atoms) number lQQat
Let it be omic%. ) The photoreceptor according to any one of claims 1 to 3, wherein the photoreceptor is provided with a surface-modified layer.