JPS61250650A - Photosensitive body - Google Patents

Abstract

PURPOSE:To obtain the titled body having an excellent chemical stability of the surface, mechanical strength and heat resisting properties and a good photosensitivity and capable of stably maintaining a high charge potential by providing a surface reforming layer on an electric charge generating layer,and an electric charge transfer layer under the electric charge generating layer respectively. CONSTITUTION:The surface reforming layer 45 composed of an amorphous hydrogenated silicon and/or a fluorated silicon carbide is provided on the electric charge generating layer 43 composed of the amorphous hydrogenated silicon and/or the fluorated silicon, and the electric charge transfer layer 42 composed of the amorphous hydrogenated silicon and/or the fluorated silicon nitride is provided under the electric charge generating layer 43. The surface reforming layer 45 has functions of an improvement of the surface potential chracteristic of the a-Si type photosensitive body, the maintenances of the potential chracteristic for a long period, and an environment resisting property, the improvements of the durability for printing, and the heat-resisting property in the application of the titled body and the thermal transfer. As the oxygen contains 1-50atom%, a relative resistance of the surface reforming layer 45 is greatly improved. Especially, the ion implantation under the high temp. or the high moisture is effectively prevented, and the maintenance of the electric charge potential is improved.

Description

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

Conventional technology Conventionally, as an electrophotographic photoreceptor, Se or Se has A s
Photoreceptors doped with ST e s S b and the like, photoreceptors in which ZnO or CdS is dispersed in a resin binder, and the like 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-3i) as a matrix have been proposed in recent years.

a-3t has a so-called dangling bond in which the bond of Si-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, by compensating for the above defects with hydrogen atoms (H) and bonding H to St,
Burying the dangling truth is done.

Such amorphous hydrogenated silicon (hereinafter referred to as a-3
It is called i:)l. ) has a resistivity in the dark of 10” to 10
9Ω-value, which is approximately 1 when compared to amorphous Se.
Therefore, a photoreceptor made of a single layer of a-3i:H has the problem that the dark decay rate of the surface potential is high and the initial charging potential is low. But on the other hand,
When irradiated with light in the visible and infrared regions, the resistivity decreases significantly, so it has extremely excellent properties as a photosensitive layer of a photoreceptor.

However, photoreceptors with a-5i:H surfaces have problems with 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-3iC:H
It is called. ), its manufacturing method and existence are “Ph11.
Mag, Vol. 35'' (1978), etc., and its characteristics include high heat resistance and surface hardness, and a high dark resistivity (10'2~
It is known that the optical energy gap changes over a range of 1.6 to 2.8 eV depending on the amount of carbon. However, there is a drawback that the long wavelength sensitivity becomes poor due to the widening of the band gap due to the inclusion of carbon.

An electrophotographic photoreceptor combining such a-3iC:H and a-3t:H has been proposed, for example, in Japanese Patent Laid-Open No. 127083/1983. According to this, a-3is
A functionally separated two-layer structure was created in which the H layer is a charge generation (photoconductive) layer and the a-3iCsH layer is provided below this charge generation layer as a charge transport layer. The a-3iC:H layer, which forms a heterojunction with the a-8i:) layer, improves the charging potential. Attenuation cannot be sufficiently prevented and the charging potential is still insufficient to be practical, and the surface contains a-3i:
The presence of the H layer causes poor chemical stability, mechanical strength, heat resistance, etc.

On the other hand, JP-A-57-17952 discloses a-3i:
A first a-3iC:H layer is formed as a surface modification layer on the charge generation layer made of H, and a second a-3iC:H layer is formed on the back surface (support electrode side).
The a-3iC:H layer is formed as a charge transport layer.

Regarding this known photoreceptor, the surface modification layer prevents attenuation, and the surface chemistry, that is, the specific resistance (dark resistivity) Po
The limit is 10'3 Ω, and since it cannot be larger than this, the ability to retain the charged potential is insufficient. Also, S
i When O2 is used in the surface modification layer, ρp increases, but active species (ions, molecules, atoms in the discharge atmosphere, etc.) generated near the charged electrode are likely to be adsorbed to the surface. Creeping discharge occurs and image deletion is likely to occur. On the other hand, a-3iC:H hardly adsorbs active species such as 5i02, but as mentioned above, ρp is insufficient and the charging potential retention ability (particularly the retention ability under high temperature and high humidity conditions) is poor.

In addition, in known photoreceptors, the charge transport ability (carrier range (μτ
) - Mobility × Lifetime) and charge retention capacity (dark resistance ρp) are sufficient, but the temperature dependence of ρ0 is large, and as a result, the charged potential retention characteristics deteriorate at high temperatures, making it impossible to put it into practical use. .

C. Purpose of the Invention The purpose of the present invention is to provide a surface that has excellent chemical stability, mechanical strength, and heat resistance, has good photosensitivity, has good charging potential retention ability, and is resistant to creeping discharge. The 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.

D. Structure of the invention and its effects, that is, the photoreceptor according to the invention contains 1 to 50 ato@ic% of oxygen (however, silicon atoms and carbon The total number of atoms and oxygen atoms is 100100ato%
shall be. ) Containing amorphous hydrogenation 0.05-5
A photoreceptor provided with a charge transport layer made of amorphous hydrogenated and/or fluorinated silicon nitride containing aton + ic% (however, the total number of atoms of silicon atoms, nitrogen atoms, and oxygen atoms is 100 atomic%) It is.

According to the present invention, an a-3iC-based surface modified layer (e.g. amorphous hydrogenated silicon carbide (a-3iC: H
), the surface modification layer consists of
Defects regarding the surface characteristics of St-based photoreceptors can be eliminated. In other words, this surface modification layer improves the surface potential characteristics of a-3i-based photosensitive photos, maintains long-term potential characteristics, and maintains environmental resistance (preventing the effects of humidity, atmosphere, and chemical species generated by corona discharge). ), it has functions such as improved printing durability due to its high surface hardness, improved heat resistance when using a photoreceptor, and improved thermal transferability (particularly adhesive transferability).

Moreover, this surface modified layer contains 1 to 50 atoa of oxygen.
+ic% (hereinafter, "atomic%" is simply written as %.

), the specific resistance of the surface modified layer is greatly improved (>)10'3Ω-aa)L, effectively preventing charge injection from the surface, especially under high temperature or high humidity conditions. The ability to hold the charged potential is significantly improved. On the other hand, if the oxygen atom content is less than 1%, such an effect will not occur, and if it exceeds 50%, image blurring will occur due to the adsorption of active species. Therefore, it is essential to set the acid group content in the surface modified layer to 1 to 50%, and preferably 5 to 30%.

Further, according to the present invention, there is provided a functionally separated photoreceptor,
Since the charge transport layer contains 0.05 to 5% oxygen, the temperature dependence of ρQ (dρp/
dT) can be kept small. For this reason, the retention characteristics of the charged potential are improved, and the upper limit of the usable temperature of the photoreceptor (
The upper limit humidity can also be increased. If the above oxygen content is less than 0.05%, the effects of oxygen content (improvement of specific resistance, control of temperature dependence) will not be exhibited, and if it exceeds 5%, there will be too much oxygen and the carrier mobility will be reduced. , that is, (μτ) decreases significantly, resulting in a decrease in sensitivity and an increase in residual potential.

Therefore, it is essential to set the oxygen content to 0.05 to 5%, and it is particularly desirable to set the oxygen content to 0.1 to 3%.

In this way, by containing a predetermined amount of oxygen in both the surface modification layer and the charge transport layer, these synergistic effects are fully exhibited, improving the charging potential and reducing the temperature dependence of the charging potential. In particular, it is possible to improve the charging potential under high temperature and high humidity conditions.

E, Example Hereinafter, the present invention will be described in detail with reference to examples.

FIG. 1 shows, for example, an A-3II electrophotographic photoreceptor 39 for positive charging according to this embodiment. This photoreceptor 39 is mounted on a drum-shaped conductive support substrate 41 such as A1.
A P-type charge blocking layer 44 made of oxygen-containing a-3iN:H (a-3iNO:H) heavily doped with an a-group element (e.g. boron);
-3iNo:H) and a-
It has a structure in which a charge generation layer (photoconductive layer) 43 made of 3i:H and a surface modification layer 45 made of oxygen-containing a-5iC:H (a-3iCO:H) are laminated. The photoconductive layer 43 has a ratio of resistivity ρD in the dark to resistivity ρL during light irradiation that is sufficiently large as an electrophotographic photoreceptor, and has good photosensitivity (particularly to light in the visible and infrared regions).

In this photoreceptor 39, based on the present invention, the surface modification layer 45 on the charge generation layer 43 contains 1 to 50% oxygen based on the total number of atoms of St, C, and O. Therefore, remarkable effects such as an increase in specific resistance and an improvement in charging potential retention ability can be obtained. That is, as shown by curve a in FIG. 2, when simply a-3iC:H is used for the surface modification layer,
Its resistivity increases according to carbon content, but 1QI5
It is known that it cannot exceed Ω-1. On the other hand, in the case of O content -3iC:H in which oxygen is contained in a-3iCsH based on the present invention (oxygen content is, for example, 5%), as shown in the curve, the specific resistance is It was confirmed that the carbon content increased significantly and showed a value far exceeding 10''Ω-1 by determining the carbon content.

This O-containing -3iC:H layer 45 is indispensable for modifying the surface of the photoreceptor and making the a-3t type photoreceptor practically excellent. 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 repeated characteristics of charging and optical attenuation are very stable, and good potential characteristics can be reproduced even if left for a long time (for example, one month or more). On the other hand, in the case of a photoreceptor with a-3i: Since H has a high surface hardness, it has abrasion resistance during processes such as development, transfer, and cleaning, and also has good heat resistance, so it can be used in processes that apply heat such as adhesive transfer.

Further, the charge transport layer 42 made of a-3iN:H contains oxygen atoms in an amount of 0.05 to 5% based on 100 atomic% of the total number of atoms of Si+N+O. The ρ0 of 42 is high even under high temperature (or high humidity), and the charged potential retention ability as a photoreceptor is stably maintained.

In order to achieve the above excellent effects comprehensively, a
-3iC: It is important to select the carbon composition of the H layer 45. That is, the carbon atom content is st+c+o=too%
It is preferably 10 to 90%, more preferably 10 to 70%. When the C content is 10% or more, the above-mentioned specific resistance becomes the desired value, and the optical energy gap becomes approximately 2.0%. OeV or more, and due to the so-called optically transparent window effect for visible and infrared light, the irradiated light is a-
It becomes easier to reach the 5isH layer (charge generation layer) 43. However, if the C content is less than 10%, the specific resistance tends to be less than the desired value, and some of the light is lost to the surface! Absorbed by 45,
The photosensitivity of the photoreceptor tends to decrease. In addition, the C content is 9
If it exceeds 0%, the amount of carbon in the layer increases, and semiconductor properties are likely to be lost, and the deposition rate when forming the a-3t:H film by the glow discharge method tends to decrease, so the C content is 90%. The following should be used.

In addition, the thickness of the a-3iC:H layer 45 is set to 400≦t≦5.
It is also important to select within the range of 000 people (especially 400 people≦t≦2000 people). That is, the film thickness is 5000
If it exceeds that of human, the residual potential VL becomes too high and the photosensitivity decreases, making it easy to lose the good characteristics of an a-3i photoreceptor. Furthermore, if the film thickness is less than 400, charges will not be charged on the surface due to the tunnel effect, resulting in an increase in dark decay and a decrease in photosensitivity.

The nitrogen atom content of the charge transport layer 42 is 30% or less, preferably 10 to 30% (the total number of Si + N + O atoms is 100%).
Let ato+mic%. ), and the appropriate film thickness is 10 to 30 μm.

Further, it is preferable that the charge generation layer 43 has a thickness of 1 to 10 crm. If the thickness of the charge generation layer 43 is less than 1 μm, the photosensitivity will not be sufficient, and if it exceeds 10 μm, the residual potential will increase, which is insufficient for practical use.

Further, in order to sufficiently prevent electron injection from the substrate 41, the charge blocking layer 44 is for positive charging, and in order to sufficiently prevent the injection of electrons from the substrate 41, an element of group Ma of the periodic table (for example, boron) is mixed at a flow rate ratio of BzHa/Si.
H+=100 to 5000 ppm T: It is good to dope it to make it P-type (or even Bi-type). Also, for negative charging,
A Group Va element of the periodic table (for example, phosphorus) may be heavily doped to make it N-type (or even episodic). The charge blocking layer 44 does not necessarily need to be provided when used for negative charging, but if provided, regardless of whether it is for positive charging or negative charging,
It is desirable to form the a-3iN:H containing 0.05 to 5%, more preferably 0.1 to 3%, of oxygen. This a-
The amount of nitrogen in 3tN:H is 30% or less, preferably 10-3
It may be set to 0%. If the blocking layer 44 has a thickness of less than 500, the blocking effect will be weak, and if it exceeds 2 μm, the charge transport ability will tend to deteriorate.

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

In particular, the hydrogen content in the photoconductive layer 43 is essential to compensate for dangling bonds and improve photoconductivity and charge retention, and is preferably 10 to 30%. This content range also applies to the surface modification layer 45, blocking layer 44, and charge transport layer 42. Further, as an impurity for controlling the conductivity type of the blocking layer 44,
In addition to boron, A6% Gas I n is used to make it P-type.
,,,, Periodic Table Ma group elements such as TI can be used, and impurities for N-type conversion can also be made from Periodic Table V elements such as A s s S b other than phosphorus.
Group a elements can be used.

The layer structure of the photoreceptor of this example is summarized as follows depending on the mode of use.

[When using positive charging]

Charge blocking layer 44: Heavily doped with an element of group Ⅰa of the periodic table. For example, B Z H6/S i H4=100
Glow discharge decomposition occurs under conditions of ~5000 ppm (capacity ratio).

Charge transport layer 42: Doped with a group Ma element of the periodic table.

Surface modified layer 45: Carbon content and oxygen content may have a concentration gradient in the thickness direction of the photoreceptor.

Charge generation N43: No doping is required.

In order to improve the charging potential and sensitivity, in some cases, an element of group 1 [a of the periodic table] may be lightly doped. For example, B 2 H6/S i H4≦20ppm (capacity ratio)
Decomposes under glow discharge conditions.

[When using negative charge]

Charge blocking layer 44: There is no particular need to provide a charge blocking layer. In order to improve charging ability, a-SiNO:H doped with Group Va elements of the periodic table in some cases.
Alternatively, a charge bronking layer made of a-SiNO:F may be provided. For example, P H3/S i H4≦200
Glow discharge decomposition occurs under conditions of 0 ppm (capacity ratio).

Charge transport layer 42: Does not need to be doped in any way.

In order to improve the charging potential and sensitivity, it may be doped with an element of group Ma of the periodic table, depending on the case.

Charge generation layer 43: Does not need to be doped in any way.

In order to improve the charging potential and sensitivity, it may be lightly doped with an element of Ha group of the periodic table. For example, B
Glow discharge decomposition occurs under the following conditions: zHa/5t) (◆≦20ppm (capacity ratio).

Surface modification N45: Carbon content and oxygen content may have a concentration gradient in the thickness direction of the photoreceptor.

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.

A drum-shaped substrate 41 is set rotatably vertically in a vacuum chamber 52 of this device 51, and a heater 55 is used to rotate the substrate 41.
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 source of SiH+ or a gaseous silicon compound, 63 is a source of 02 or a gaseous oxygen compound, and 64 is a source of C
65 is a supply source of nitrogen compound gas such as NH, N2, etc., 66 is a carrier gas supply source such as Ar, and 67 is an impurity gas (e.g. 82H6, PH3
) supply source, 68 is each flow meter. In this glow discharge device, first, the surface of a support, for example, an A1 substrate 41, is cleaned, and then placed in a vacuum chamber 52, and the gas pressure in the vacuum chamber 52 is adjusted to 10-6 Torr and evacuated. , and the substrate 41 is heated to a predetermined temperature, particularly 100 to 350°C (
The temperature is preferably maintained at a temperature of 150 to 300°C. Next, using a high purity inert gas as a carrier gas, SiH+
or gaseous silicon compounds, CH4, N2 or NH3,
02, B2H6 (or PHa) 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-mentioned reaction gases is decomposed by glow discharge between the electrode 57 and the substrate 41, and the 0-containing P type a-SiN:H1010 content iN:H
Sa-3t:H% O content-3iC:H is deposited continuously (W, corresponding to the example of FIG. 1) on the substrate in the above-mentioned baths 44, 42, 43, 45.

In the above manufacturing method, since the support temperature is set at 100 to 350° C. in the step of forming the a-3i layer on the support, the film quality (particularly the electrical properties) of the photoreceptor can be improved.

In addition, when forming each layer of the above a-3t photoreceptor,
In order to compensate for dangling bonds, fluorine is introduced in the form of SiF+ instead of the above-mentioned H or in combination with H, and a-3i:F, a-3t:H:FSa-3
iN:FSa-3iN:H:F,a-3iC:F,a-
3iC:H:F can also be used. In this case, the amount of fluorine is preferably 0.5 to 10%.

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 (Patent Application No. 54-152) filed by the present applicant)
The above photoreceptor can also be manufactured by the method of No. 455).

Next, the present invention will be explained using a specific example.

By glow discharge decomposition method, the first
An electrophotographic photoreceptor having the structure shown in the figure was manufactured.

That is, first, after cleaning the surface of the support, for example, a drum-shaped AJ substrate 41 having a smooth surface, it is placed in a vacuum chamber 52 shown in FIG. 3, and the gas pressure in the vacuum chamber 52 is set to 10=
Torr and exhaust the air, and keep the substrate 41 at a predetermined temperature, particularly 100 to 350°C (preferably 150 to 350°C).
Heat and maintain at 300°C. Next, high-purity Ar gas was introduced as a carrier gas, high-frequency power with a frequency of 13.56 MHz was applied under a back pressure of 0.5 Torr, and preliminary discharge was performed for 10 minutes.

Next, a reaction gas consisting of SiH+ and B2H6 was introduced, and the flow rate ratio was 4:l:l: (1,0X10″2):(
(Ar+StH++N2+O
z+B 2 Hs) By glow discharge decomposition of the mixed gas, P-type 0-containing a-
A 3iN:H layer 44 was formed to a predetermined thickness at a deposition rate of 5 pm/hr. The charge transport layer 42 was also formed in the same manner. Subsequently, the supply of -B 2 Hs and N2 is stopped, and S i H4 is discharge decomposed to form a-3t:H of a predetermined thickness.
Layer 43 was formed. Subsequently, the flow rate ratio 4:1:6:
(Ar+SiH4+CH4+0 of (1,0xlO°1)
2) Glow discharge decomposition was performed together with a mixed gas, and a 0-containing a-3iC:H surface protective layer 45 of a predetermined thickness was further provided to complete an electrophotographic photoreceptor.

The following measurements were performed using this photoreceptor.

Charged potential V o (V): Using a modified U-BiX2500 (manufactured by Konishi Roku Photo Industry ■), a 360SX type electrometer (
Surface potential measured just before development using a Trek (manufactured by Trek).

Half-reduced exposure amount E 1/2 (lux -5ec)
: Using the above device, set the surface potential to 500V to 250V.
The amount of exposure required to reduce the amount of light by half. For image exposure, long wavelength components of 620 nm or more were cut using a dichroic mirror. (The exposure amount was measured using a 550-1 light intensity needle (manufactured by EGandG)) After charging to 500 V using the above device, the residual potential Vλ
Surface potential after 1ux-see irradiation.

200,000 copies live action: U-Bix 2500 modified machine (
(manufactured by Konishiroku Photo Industry ■) was used. The image quality evaluation is as follows.

◎ The image density is sufficiently high, the resolution and gradation are good, the image is clear and there are no white lines or white spots on the image.

In other words, the image is extremely good.

○ Good image.

8. Can be used for practical purposes.

×　Image cannot be used for practical purposes.

The results shown in FIG. 4 were obtained for photoreceptors with various layer configurations. The following is clear from this result.

(1) If the oxygen content of the surface-modified layer is less than lat%, or if the oxygen content of the charge transport layer is less than 0.05 at%, the charging potential will not be sufficient in a high-temperature environment.

(2) If the oxygen content of the surface modified layer is more than 50 at% or the oxygen content of the charge transport layer is more than 5 at%,
Photosensitivity deteriorates and residual potential increases.

(3) If the oxygen content of the surface-modified layer exceeds 50 at%, the resolution of the image after 200,000 copies will deteriorate.

Therefore, in order to obtain good image quality even if 200,000 copies are made at 50°C, the oxygen content of the surface modified layer must be lat%≦[0
]≦50a t%, and the oxygen content of the charge transport layer is 0.
It is necessary that 05at%≦(0)≦5at%.

[Brief explanation of drawings]

Figures 1 to 4 show examples of the present invention. Figure 1 is a cross-sectional view of a-3t-based nausea, and Figure 2 is a graph comparing the specific resistance of a-3iC. , FIG. 3 is a schematic sectional view of the glow discharge device, and FIG. 4 is a diagram showing a comparison of the characteristics of the photoreceptor. In addition, in the symbols shown in the drawings, 39......a-8i photoreceptor 41...
...Support (substrate) 42 ...Charge transport layer 43 ...Charge generation layer 44 ...Charge blocking layer 45 ...
......Surface modified layer.

Claims (1)

[Claims] 1. 1 to 50 atomic% oxygen on a charge generation layer made of amorphous hydrogenated and/or fluorinated silicon.
(However, the total number of atoms of silicon atoms, carbon atoms, and oxygen atoms is 100 atomic%.) A surface modification layer made of amorphous hydrogenated and/or fluorinated silicon carbide containing is provided, and the charge generation layer At the bottom, add 0.05 to 5 atomic% oxygen (however, the total number of silicon atoms, nitrogen atoms, and oxygen atoms is 100 atomic%).
c%. ) A photoreceptor provided with a charge transport layer comprising amorphous hydrogenated and/or fluorinated silicon nitride. 2. Add 0.05 to 5 atomic oxygen under the charge transport layer.
% (however, the total number of atoms of silicon atoms, nitrogen atoms, and oxygen atoms is 100 atomic %). A photoreceptor as described in item 1 of the scope.