JPS5967553A - Recording body - Google Patents

Abstract

PURPOSE:To provide and electrophotographic material which exhibits excellent sensitivity to light in visible and IR regions by providing a specific electric charge blocking layer, photoconductive layer and surface reforming layer on the substrate of said material. CONSTITUTION:A photoconductive layer 3 consisting of nitrogen atom-contg. amorphous hydrogenated and/or fluorinated silicon contg. 1-30atom% nitrogen atoms is provided on a backing substrate 1. A surface reforming layer 4 and/or electric charge blocking layer 2 of nitrogen atom-contg. amorphous hydrogenated and/or fluorinated silicon layer contg. 50-90atom% nitrogen atoms are formed on the upper and/or lower sides of the photoconductive layer. Since the layer 3 is formed on the a-Si contg. 1-30atom% nitrogen atoms in the above-mentioned way, said layer exhibits excellent sensitivity to the light in visible and IR regions by controlling the quantity of nitrogen and the intrinsic resistance is controlled as desired with the quantity of nitrogen and the rate of impurity doping.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording medium, such as an electrophotographic photoreceptor.

Conventionally, as an electrophotographic photoreceptor, Se1 or Se has As,
Photoreceptor doped with Te, Sb, etc., znO or CdS
Photoreceptors, etc., in which the compound is dispersed in a resin binder are known. However, these photoreceptors have problems in terms of environmental pollution, thermal stability, and mechanical strength.

On the other hand, electrophotographic photoreceptors using amorphous silicon (a-8t) as a base material have been proposed in recent years.

a-8t has a so-called dangling bond in which the bond of 5t-8t 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, we replaced the above defects with hydrogen atoms (
The dangling bonds are filled by bonding H to Sl with compensation by H).

Such amorphous hydrogenated silicon (hereinafter referred to as a-8
It is called t:H. ) has a resistivity in the dark of 10'~10@
Ω-m, which is about 1/10,000 times lower than that of amorphous Se. Therefore, a photoreceptor made of a single layer of a-8t: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.

Therefore, in order to impart potential holding ability to such a-8i:H, the resistivity was reduced to about 10 by doping with boron.
′! However, it is not easy to control the amount of boron so precisely, and
Even with a resistivity of about 12 Ω-m, the photosensitivity is insufficient for use in a photosensitive process using the Carlson method, and the charge retention properties are still insufficient. In addition, by introducing a small amount of oxygen together with boron, it is possible to increase the resistance to the level of 10130-sub, but when this is used in a photoreceptor, the photoconductivity decreases, leading to worsening of edge breakage and The problem arises of the generation of residual potential.

In addition, photoreceptors with a-8t:H surfaces are susceptible to surface chemical stability, such as the effects of long-term exposure to the atmosphere and moisture, and the effects of chemical species generated by corona discharge. Sufficient consideration has not been made until now. For example, it is known that if a device is left for more than a month, it will be affected by moisture and its receptive potential will drop significantly. Furthermore, a-8,i:H
has poor film adhesion (adhesion) to supports such as AI and stainless steel, which poses a problem in practical use as electrophotographic photoreceptors.

As a countermeasure to this, an adhesive layer made of an organic polymer compound such as a silane coupling agent as in JP-A No. 55-87154, a polyimide resin as in JP-A-56-74257, or a triazine resin is used as the a-8t:H layer. It is known that it is provided between the support body and the support body.

However, in these cases, the formation of the adhesive layer and the a-8i
: It is necessary to perform the film formation of the H layer by a different method, and therefore a new film forming apparatus must be used, resulting in poor workability.

Moreover, in order to make the a-8i:H layer have good photoconductivity, the temperature of the substrate (support body) during film formation is usually about 200°C.
℃ or higher, but the underlying adhesive layer cannot thermally withstand such temperatures.

On the other hand, forming a photoconductive layer using nitrogen atom-containing a-8t:H (hereinafter sometimes referred to as a-8iN:H), in which nitrogen atoms are contained in a-8i:H, was disclosed in Japanese Patent Application Laid-Open No. It is described in each specification of No. 54-145539 and Japanese Patent Application Laid-open No. 57-37352. This known a-8iN:H layer can be increased in dark specific resistance f)D to approximately 1X10''Ω-m by doping with boron, and also has excellent photoconductivity (sensitivity). According to the inventor's study, in the above-mentioned known photoreceptor, a-8iN:
It has been found that injection of unnecessary charges from the conductive support into the H layer is likely to occur.

Alternatively, there are examples in which a surface coating layer is provided on the a-8iN:H layer, but since the surface coating layer is simply made of synthetic resin, it has poor printing durability, heat resistance, and durability during repeated use. It was also found that the stability of the electrophotographic properties, chemical stability of the surface, mechanical strength, etc., were not sufficient. Moreover, since the above-mentioned surface coating layer easily absorbs or reflects light that should be incident on the a-8iN:H layer, it also has the disadvantage of reducing photosensitivity.

The present invention has been made in order to correct the above-described defects.
In a recording body having a photoconductive layer made of amorphous hydrogenated and/or fluorinated silicon (e.g. a-8iN:H) containing nitrogen atoms, nitrogen atoms are added above and/or below the photoconductive layer. 50~90atomie%
This relates to a recording medium characterized in that a nitrogen atom-containing amorphous hydrogenated and/or fluorinated silicon (e.g. a-8iN:H) layer is formed as a surface modification layer and/or a charge blocking layer. Chiru.

According to the present invention, since the photoconductive layer contains 1 to 30 atomic% of nitrogen atoms and is formed of 9a-8i, it exhibits excellent sensitivity to light in the visible and infrared regions depending on the nitrogen content, Moreover, the specific resistance can be controlled arbitrarily by changing the amount of nitrogen and the amount of impurity doping.

In particular, since it exhibits a PD of 10100-m or more when doped with boron or the like, it becomes a photoconductive layer with excellent photosensitivity and potential holding ability.

Moreover, it is extremely characteristic that an a-8i layer containing 50 to 90 atomic% of nitrogen atoms is provided on the upper and/or lower side of this photoconductive layer as a surface modification layer and/or a charge blocking layer. 0, that is, the surface modified layer has high heat resistance and surface hardness, and has a thickness of 50 to 90 atoms.
Depending on the amount of nitrogen, it functions as a window material that can effectively transmit light in the visible and infrared regions. For this reason, printing durability,
It is possible to significantly improve heat resistance, photosensitivity, stability of electrophotographic properties during repeated use, chemical stability of the surface of the photoreceptor, mechanical strength, prevention of changes over time during storage, etc.

Further, as a charge blocking layer, the nitrogen atom-containing a-
When the 8T layer is provided, it exhibits high resistance due to the nitrogen content of 50 to 90 atomic %, prevents unnecessary injection of carriers from the substrate, and significantly improves the ability of the photoreceptor to retain the charged potential. Adhesion is also sufficient.

This blocking effect is further improved by impurity doping.

In addition, since the photoconductive layer and charge blocking layer (or surface modified layer) in the present invention are made of a-8t with different amounts of nitrogen, each layer can be formed continuously by simply changing the amount of nitrogen supplied using the method described below. This results in very good workability and controllability.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.

1 to 5 illustrate the structure of the photoreceptor.

The photoreceptor shown in FIG. 1 has a conductive support substrate 1 made of At, etc.
The photoconductive layer 3 consists of a-8iN:H (nitrogen content 1 to 30 atomic%), and a=sfN:H (nitrogen content 50 to 90 atomic%).
It has a structure in which surface modified layers 4 made of atomic %) are sequentially laminated.

In particular, the photoconductive layer 3 has a nitrogen atom content of 1 to 30 at
omi: c% (preferably 15-25 atomic%
), as shown in Figure 6, the ratio of the dark resistivity 9D and the resistivity 9L during light irradiation is sufficient, and the photosensitivity (% to visible and infrared light) is Becomes good.

In addition, elements of group 11TA of the periodic table, such as boron, are added at a flow rate ratio (B, Ha/SiH,) = 1 to 500 ppm, which will be described later.
As shown in Figure 7, it is possible to make the resistivity higher by increasing the resistivity to 10'10 Ω-m or more (or even more than 10'10-m) by pinking it. can be improved.

As a result, a photoconductive layer having good photosensitivity and potential holding ability can be obtained. For comparison, the dashed line in Figure 7 shows the resistance change due to impurity doping to a-8t:H. A stable high resistance value can only be obtained at around -m. Further, as understood from FIG. 6, in a-3iN:H, 9 can be controlled by the amount of nitrogen, and in combination with impurity doping, the range of resistance control can be widened. Further, as shown in FIG. 8, the photoconductive layer 3 has an optical energy gap (approximately 1.65 e in the case of a-8i:H) as the nitrogen content increases.
It can be seen that by increasing V ), the absorption characteristics for incident light can be controlled.

Note that the lower part of the photoconductive layer 3 (the boundary side with the support 1) can be made into a P-type or N-type by doping with a Group IIA or Group VA element of the periodic table, for example, boron or phosphorus at a high concentration. For example, by making it P-type (or even P-type), it is possible to sufficiently prevent the injection of electrons from the substrate during positive charging. ,H,/SiH,=1000~100,0
It is preferable to dope at 0.00 ppm. When the N-type (furthermore, + is N-type), the injection of holes from the substrate during negative charging is sufficiently prevented, and the amount of phosphorus doped for this purpose is PH3/SiH, ~10 to 10, expressed as a flow rate ratio. 000
It is preferable to set it as ppm.

The surface modified layer 4 has a thickness of 50 to 90 atomic 'XI
As shown in Fig. 6, the specific resistance is small and the surface potential retention is improved, and as shown in Fig. It has sufficient transparency for light (target long wavelength light).

In the example of FIG. 2, a-8 having the same composition as the surface modified layer 4 is shown.
iN:H (nitrogen -50 to 90 atomic%) was formed as a charge blocking layer 2 under the photoconductive layer 3.

This blocking layer 2 contains 50 to 90 nitrogen atoms.
Since it is set to atomic%, the specific resistance can be made to be 10'3Q=cm or more as shown in FIG. 6, and the ability of the photoreceptor to hold the charged potential can be improved. In order to enhance the blocking effect, the a-8iN:H layer 2 can be made into N-type (or even +N-type) by doping with a Group VA element of the periodic table (e.g. phosphorus), or it can be doped with an element of Group 1'IIA of the periodic table (for example, phosphorus). For example, by doping with boron), the a-8iN:H layer 2
It is better to make it P-type (or even PH-type).

FIG. 3 shows an example in which the a-8iN:H layers 4 and 2 are provided as a surface modification layer and a charge blocking layer, respectively. Such a three-layer structure provides the above-mentioned surface modification effect and It becomes an excellent photoreceptor that can also exhibit blocking effects. 4 and 5 show that the blocking layer 2 is made into an N-type or a P-type by doping with impurities similar to the above, and the blocking effect is further improved.

The thickness of each layer of the photoreceptor described above also has an appropriate range, and the thickness of the photoconductive layer 3 is 2 to 80 μm (preferably 5 to 30 μm).
μm), blocking layer 2 is 100X to 1μm (preferably 400 to 5000A), surface modification layer 4 is 1oo to 5μm
000X (preferably 400 to 2000X). If the thickness of the photoconductive layer 3 is less than 2 μm, the charging potential will not be sufficient, and if it exceeds 80 μm, it will be unsuitable for practical use, and it will take time to form the film. Blocking layer 2
If it is less than 1 ooX, there will be no blocking effect, and if it exceeds 1 μm, the charge transport ability will be poor.

Moreover, if the surface modification layer 4 is less than 100X, it will not be effective, and if it exceeds 50,001X, the photosensitivity will decrease, the residual potential will increase, etc., and this will become unsuitable.

Note that each of the above layers needs to contain hydrogen, but if they do not contain hydrogen, the charge retention characteristics of the photoreceptor will not be practical.

Therefore, the hydrogen content is between 1 and 40 atomic%
(Furthermore, it is desirable to set it as 10-30 atomic%). In particular, the hydrogen content in the photoconductive layer 3 is essential to compensate for dangling bonds and improve photoconductivity and charge retention, and is usually 1 to 40 at.
atomic%, and more preferably 3.5 to 20 atomic%. In addition, as a doping impurity,
In addition to boron, elements of the IrA group of the periodic table such as At, Ga, and InXTt can be used, and in addition to phosphorus, As, Sb,
It can be doped with a Group VA element of the periodic table, such as Bi.

In addition, in order to compensate for dangling bonds, fluorine can be introduced in place of the above-mentioned H or in combination with H.
-8iN:FXa-8iN:H:F can also be used. In this case, the flute firefly is 0.01 to 20 atomic
%, more preferably 0.5 to 10 atomic%.

Next, the method and apparatus (glow discharge apparatus) for manufacturing the above-mentioned photoreceptor will be explained with reference to FIG.

In the vacuum chamber 12 of this apparatus 11, the above-described substrate 1 is fixed on a substrate holding part 14, and a trap is formed so that the substrate 1 can be heated to a predetermined temperature by a heater 15. A high frequency electrode 17 is disposed facing the substrate 1, and a glow discharge is generated between the high frequency electrode 17 and the substrate 1. In addition, 20.21.22.2 in the figure
3.25.27.28.29.30.37.38.4o
is each pulp, 32 is a source of SiH or a gaseous silicon compound, 33 is a source of nitrogen such as NH3 or N2, 3
4 is a carrier gas supply source such as Ar or H2, and 35 is an impurity gas (eg, B, H6, or PH) supply source.

In this glow discharge device, first, the surface of a support, for example, an At substrate 1, is cleaned and then placed in a vacuum chamber 12, and the vacuum [e and valve 37 are adjusted so that the gas pressure in the 12 becomes 16' Torr. Then, the substrate 1 is heated and maintained at a predetermined temperature, for example, 30 to 400°C. Then,
Using a high-purity inert gas as a carrier gas, a mixed gas such as B, H, etc. prepared by diluting an appropriate amount of SiH or a gaseous silicon compound and NH8 or N is introduced into the vacuum chamber 12, for example, 0. The high frequency voltage of the high frequency power supply 16 (e.g. 13.56
MH2) is applied. As a result, each of the above reaction gases is decomposed by glow discharge, a-8IN:H, and a-8 containing hydrogen.
iN:H, a-8iN:H are sequentially deposited on the substrate as layer 2.3.4 above. At this time, a-8i 1-xNx :H having a desired composition ratio and optical energy gap can be precipitated by appropriately adjusting the flow rate ratio of the silicon compound and the nitrogen compound and the substrate temperature. It is possible to deposit at a rate of 1000 A/min or more without significantly affecting the electrical properties of the film.

In this way, a-5iN according to the invention:)(/a
A photoreceptor made of -8iN:H/a-8iN:H can be produced by sequentially forming each layer using the same apparatus by simply changing the flow rate of the reaction gas used.

The above manufacturing method is based on the glow discharge decomposition method, but there are also sputtering methods, ion plating methods, and methods 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. 54-152) filed by the present applicant)
The above photoreceptor can also be manufactured by the method of No. 455).

In addition to SiH4, the reaction gases used include Si, H, and S.
iF, 5iHF, or derivative gases thereof can be used.

FIG. 10 shows a photoreceptor according to the present invention described above in JP-A-56-7.
8413).

The Pel jar 41 is connected to a vacuum pump (not shown) via an exhaust pipe 43 having a butterfly valve 42, thereby causing the inside of the Pel jar 41 to be heated, for example, from 10-3 to HY''.
The substrate 1 is placed in the Pel jar 41 and heated to a temperature of 150 Torr by the heater 45.
While heating to ~500°C, preferably 250~450°C, a DC negative ridge pressure of 0~-IOKV, preferably -1~-6KV is applied to the substrate 1 by the DC power supply 46, and its outlet faces the substrate 1. While introducing active hydrogen and hydrogen ions from a hydrogen gas discharge tube 47 with an outlet connected to the Pelger 41 into the Pelger 41, a silicon evaporation source 48 provided facing the substrate 1 and, if necessary, The aluminum evaporation source 49 is heated and each upper shutter S is opened to simultaneously evaporate silicon and aluminum at an evaporation rate of, for example, 1:10-', and the discharge tube 50 is heated into the Pelger 41. Introducing activated NH gas, thereby forming a-8iN:H layers 3 and 2 and/or 4 (see Figures 1 to 5) containing a predetermined amount of aluminum if necessary. do.

For example, the structure of the discharge tube 47, 50 is shown in FIG. 11, as shown in FIG. , a discharge space member 64 made of, for example, cylindrical glass surrounding the discharge space 63, and another ring-shaped electrode member 6 provided at the other end of the discharge space member 64 and having an outlet 65.
6, by applying a DC or AC voltage between the one electrode member 62 and the other electrode member 66, hydrogen gas, for example, supplied through the gas port 61 is discharged into the discharge space 63. A glow discharge is generated at the outlet 6, and active hydrogen and ionized hydrogen ions, which are composed of hydrogen atoms or molecules activated by electron energy, are discharged from the outlet 6.
5. It is discharged. The discharge space member 64 in this illustrated example has a double pipe structure and is configured to allow cooling water to flow therethrough, and 67 and 68 indicate a cooling water inlet and an outlet. 69 is a cooling fin for one electrode member 62. The distance between the electrodes in the hydrogen gas discharge tube 47 is 10 to 15α,
The applied voltage is 60o■, and the pressure in the discharge space 63 is 1o-2T.
It is said to be about orr.

Next, examples of the present invention will be specifically described.

The A1 substrate cleaned with trichlorethylene and etched with 0.1% NaOH water solution and 0.1% HNO3 water solution was placed in the glow discharge device shown in Fig. 9, and the inside of the reaction tank was heated for 10 minutes.
Evacuate to a high vacuum level on a Torr stand and set the support temperature to 200℃.
After heating to ℃, high purity Ar gas was introduced and the temperature was set to 0.5 Torr.
A high frequency power with a frequency of 13.56 MHz and a power density of 0.04 W/r:A was applied under a back pressure of r, and a preliminary discharge was performed for 15 minutes. In the formation of the photovoltaic layer, charge pronking layer, and surface modification layer, SiHN1,
And if necessary, discharge decomposition of B and H6, each a -8iN
:H layer was formed.

The electrophotographic photoreceptor thus prepared was mounted on an electrometer SP-428m (manufactured by Kawaguchi Electric Co., Ltd.).
The voltage applied to the charger discharge electrode is set to 6'v,
A charging operation is performed for 5 seconds, and the charged potential of the photoreceptor surface immediately after this charging operation is set to Vo (V). -sec).

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,(,Y)).

In addition, regarding image quality, we created the photoreceptor in the form of a drum, and
Electronic 4-speed copying machine U-Bix V (at 0°C and 60°RH)
(manufactured by Konishiroku Photo Industry Co., Ltd.) to create an image.
The initial image quality (at one time after 1000 copies) and the image quality upon multiple use (at one time after 200,000 copies) were evaluated as follows.

Image density 1.0 or more ◎ (Very good image quality) 0.
6 to 1.0 0 (Good image quality) Less than 0.6 Δ (Blurred image occurs) Each photoreceptor according to the present invention is shown in FIG. 12 together with a comparative example.
If the photosensitive layer is doped with impurities and the amount of nitrogen is controlled, the characteristics will be significantly improved. It can also be seen that good results can be obtained by appropriately selecting the composition and thickness of this photosensitive layer, blocking layer, and surface modification layer.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1, FIG. 2, FIG. 3, FIG. 4, and FIG. 5 are five cross-sectional views of the photoreceptor, and FIG. Figure 7 is a graph showing the resistance change of a-8iN:I( due to impurity doping).
Figure 8 is a graph showing changes in the optical energy gap of a-8iN:H depending on the amount of nitrogen, Figure 9 is a schematic cross-sectional view of a glow discharge device, and Figure 10 is a graph of a vacuum evaporation device. FIG. 11 is a schematic cross-sectional view of the gas discharge tube, and FIG. 12 is a diagram showing each characteristic of the photoreceptor. In addition, in the symbols shown in the drawings, 1------1 support substrate 2--------s-8iN:H layer (blocking layer) 3
------a-8iN: H layer (photoconductive layer or photosensitive layer) 4
------a-8iN:H layer (surface modified layer). Representative Patent Attorney Hiroshi Aisaka 1st day 2nd day 50th a-Sノ1-xNx:H 7th day PH%H4゜A/, B″%8i7M 90th day

Claims (1)

[Claims] 1. A substrate, formed on this substrate and containing 1 to 1 nitrogen atoms.
In a recording body having a photoconductive layer made of amorphous hydrogenated and/or fluorinated silicon containing nitrogen atoms containing 30 atomic%, 50 to 90 atoms of nitrogen atoms are added above and/or below the photoconductive layer.
A recording medium characterized in that an amorphous hydrogenated and/or fluorinated silicon layer containing s-containing nitrogen atoms is formed as a surface modification layer and/or a charge blocking layer. 2. The nitrogen atom content of the photoconductive layer is 15 to 25 atoms.
c%, the recording medium according to claim 1. 3. The recording medium according to claim 1 or 2, wherein the photoconductive layer has a specific resistance of 0 10 Ω-cnr or more due to doping with an element of group 1 rtA of the periodic table. 4. The recording medium according to claim 3, wherein the photoconductive layer has a specific resistance of 10'10-m or more due to doping with an element of group mA of the periodic table. 5. The thickness of the photoconductive layer is 2 to 80 μm1 The thickness of the charge blocking layer is 100 A to 1 μm1 The thickness of the surface modification layer is 10 μm
0 to 5000 A, the recording medium according to any one of claims 1 to 4. 6. The recording medium according to claim 5, wherein the photoconductive layer has a thickness of 5 to 30 μm, the charge blocking layer has a thickness of 400 to 5000 A, and the surface modification layer has a thickness of 400 to 2000 A.