JPS6022382A - Photoconductive member - Google Patents

Abstract

PURPOSE:To form parts, where the concentration of addition impurities has been continuously changed in the interface between each layer, as well as to eliminate the peeling-off of a semiconductor film due to the difference of distortion in the film by using the semiconductor film as a barrier layer and also to prevent the rise of the residual potential. CONSTITUTION:A barrier layer 3 consisting of an amorphous silicon is deposited on the surface of an aluminum or the surface of a conductive substrate 2, whose surface has been performed an oxidation treating. Elements of IIIa Group and Va Group, the Periodic Table, are dopped on the barrier layer 3 and the specific resistance of the layer 3 is controlled in such a way that the specific resistance of the first barrier layer 3a becomes 10<7>OMEGAcm or thereabouts and the specific resistance of the second barrier layer 3b becomes 10<13>OMEGAcm or thereabouts. A photoconductive layer 4 consisting of an amorphous semiconductor, which has been formed using silicone atoms involving hydrogen doped with boron as the parent body, is formed on the barrier layer 3 and a surface coated layer 5 is formed on the surface of the layer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Fan Ming's Techniques] P] This invention relates to an optical four-electronic member such as an electrophotographic JX, a photoreceptor, or an image sensor that can be used in an electrophotographic apparatus.

[Technical background of the invention and its problems]

Light 4-electronic light (light in the wavelength range from ultraviolet to visible to infrared,
It is sensitive to electromagnetic waves such as rays and gamma rays, and is used in electrophotographic photoreceptors, image sensors, etc. Generally, for the purpose of use, this type of photoconductive member is required to have electrical properties that have a high specific resistance in the dark (for example, 10 Ω or more) and that the specific resistance decreases when irradiated with light. Taking as an example an electrophotographic photoreceptor used in an electrophotographic apparatus, the conditions required as a photoconductive member will be explained.

As is well known, the principle of electrophotography is to apply an image to the surface of a photoreceptor using corona discharge or other methods (by applying an electric charge to the surface of the photoreceptor, and then applying an electric charge to the surface of the photoreceptor). A carrier pair with a hole is generated, and one of them neutralizes the charge on the surface of the photon 1 to form a 1'i# electrostatic latent image.

That is, when the surface of the photoreceptor is positively charged, the positive R charge on the photoreceptor surface is neutralized by electrons among the carrier pairs generated by the image forming light, and a potential nozzle due to the positive charge is created on the surface. A large turn is formed.

The electrostatic latent image formed in this way is visualized by applying a developer charged at a polarity different from that of the surface of the photoreceptor to the surface of the photoreceptor using Coulomb force. Ru.

At this time, in order to prevent the developer from adhering to the light-irradiated area of the photoreceptor surface (so-called fogging phenomenon), the developer should be lower than the α-position of the light-irradiated area of the photoreceptor with respect to the ground potential of the photoreceptor. A developing bias of about 200 to 300 V is usually applied to increase the potential.

Further, a reversal development method is often employed in laser glinters and the like, but in this case, a developing bias of a potential is applied so that the developer adheres to the light irradiated portion of the photoreceptor.

The main conditions required for an electrophotographic photoreceptor used in such an electrophotographic apparatus are the following width.

A. Charges on the surface of the photoreceptor applied by corona discharge or other means are retained for a certain period of time (good α charge retention ability) OB: Electrons and holes generated by light irradiation of the photoreceptor One carrier neutralizes the charge on the surface of the photoreceptor, and the other carrier instantly reaches the support of the photoreceptor without recombining the carrier pair.

Conventionally, amorphous chalcogenide-based materials have been used for this type of photoreceptor. This has the characteristics that it is easy to increase the area and provides excellent light guiding properties. However, since the original absorption edge is close to the visible to ultraviolet region, the sensitivity to light in the visible region is low in practical use, and the surface hardness is low, resulting in a short life as an electrophotographic photoreceptor.

Therefore, optical 4 TL (components) using amorphous silicon have recently been considered.This material has a wide absorption wavelength range, is panchromatic, and has the features of high sensitivity and high hardness. It is harmless to the human body, and has the advantage of being cheaper and easier to grow over a large area than single-crystal silicon5, but it usually has a specific resistance in the dark of l
It has a drawback that the charge retention ability is not sufficient when used as a secondary photoreceptor.Therefore, in recent examples of applying amorphous silicon to photoreceptors, photoconductive An amorphous silicon film whose specific resistance is increased by adding nitrogen, carbon, or oxygen between the carrier generation layer and the support layer that supports it, or a non-crystalline silicon film doped with impurities. Alternatively, a semiconductor film made of amorphous silicon with n-type conductivity (a φ-type semiconductor that blocks electrons and allows holes to pass when the charged polarity of the photoreceptor is positive) is used; In the negative case, conversely, using an n-type semiconductor) is being considered as a barrier layer.

Such means improve the charge retention ability of the photoreceptor, but in the case of the former, increasing the thickness of the barrier layer also prevents the passage of carriers flowing from the carrier generation layer to the support layer. As a result, the residual potential becomes high, and if the film thickness is made thin, there is a drawback that dielectric breakdown occurs due to the development bias described above.

On the other hand, in the case of the latter, such problems due to film thickness do not occur, but due to doping with impurities (amorphous silicon becomes an n-type semiconductor by doping with Group Ia elements), The drawback is that the strain in the layer becomes large. If this narrow layer is used as a barrier layer and a carrier generation layer is formed on it, film peeling will occur due to the difference in strain in the layer.

[Purpose of the invention]

The non-invention is the above-mentioned % + (it was done out of curiosity,
The purpose is to provide all n'11-heavy members with excellent photoconductive properties and no peeling caused by strain differences in the film.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention prevents film peeling by forming a part in which the four geese of the speaking force II impurity' proboscis are continuously changed at least at the interface of the six layers. It is.

In addition, the present invention provides a photoconductive member which uses half z* h + oxide as a barrier layer to prevent an increase in residual potential, and further improves the charge retention ability and has excellent photodioelectric properties.

[Embodiments of the invention]

Hereinafter, an explanation will be given of an example in which the present invention is applied to an electrophotographic photoreceptor for positive charging.The photoconductive member according to the present invention is applicable not only to the child photoreceptor shown in this example, but also to It can also be applied as an image sensor. In this case, the support layer, the semi-solid layer (barrier layer), and the photoconductivity 1? A transparent electrode (ITO) is provided as a common electrode on the light receiving side of the image assembly as
), a semi-integrated layer, a photoconductive layer and/or a high resistance layer in contact with the individual electrodes, respectively.

Now, FIG. 1 is a sectional view showing the layer structure of an electrophotographic photoreceptor 1 according to the invention.

This photoreceptor 1 is formed by forming multiple layers on a support 2 as a first layer made of aluminum or whose surface is oxidized.
a barrier layer 3 as a layer, a photoconductive layer 4 as a third layer
and a surface coating layer 5 as a fourth layer are formed in this order. The barrier layer 3 is a P-type semiconductor layer formed in one or two layers as shown in the examples described later, and stops the injection of carriers from the support 2 and also prevents the injection of carriers from the optical tetracentric layer 4. It acts to allow outflow. )(2/,
l: 'I[62]U layer 4 is sensitive to Nor; and generates carrier pairs of +(tetratons and holes) by light irradiation. Surface coating layer 5 is sensitive to Nor; It has the function of preventing the +lW charge applied to the surface from flowing out, but as a general A, conductive member, it has the function of mechanically protecting the surface (
(not yet) has the effect of improving the adhesion of the film to other layers.

The six layers of the photoreceptor having such a structure are formed from the following materials in terms of materials 1 and F. First, the barrier layer 2 is made of boron (B), fully doped carbon (c), and hydrogen. Silicon (Si) which expresses α force
The purpose of doping with OB, which is an amorphous semiconductor of PM, is to control valence electrons and make the conductive type of the barrier layer 2 P-type. It is effective for improving the specific resistance of 1't4 dogs.

Each layer 4 of the optical fiber 1 is an amorphous semiconductor whose matrix is 8i atoms containing H doped with B, and is sensitive to light and generates carriers when irradiated with light. In this case, the doping of B makes the photoconducting layer 4 an intrinsic semi-274.
This is done in order to have conductive properties similar to those of a body.

5 surface covering layers, 8 containing C and H doped with B
It is a P-type amorphous semiconductor with an i atom as its host.

The reproduction of each layer is such that the barrier layer 3 has a thickness of about 5 μm and the photoconductive layer 4 has a thickness of 1 μm.
It is preferable that the surface coating layer 5 has a thickness of about 2 μrn and a surface coating layer 5 of 0.05 μm and 8 degrees.

The +1 child photographic photoreceptor having the above structure can be produced by, for example, producing an electrophotographic photoreceptor using a plasma CVD method as shown in FIG. The photographic photoreceptor manufacturing apparatus includes a vacuum chamber 14 as a reaction container airtightly mounted on a base 12, and an exhaust device such as a mechanical booster pump 18 and a p-tally pump 20 connected to the base 12 via a pipe 16. The pressure inside the vacuum chamber 14 is, for example, 10 to 10 Torr KaR. On the base 12' in the vacuum chamber 14, a drum holding device 22 is erected and rotated by a drive device 26 via a key 'l' 2 /I. This drum holding Aj4'J, 22 is an aluminum drum-shaped spring [iεNote/I layer (,28(!
(shown as support 2 in 1)
The drum-shaped conductive substrate 28 is heated to a predetermined crystallinity, for example, from 100 to 400 DEG C., by using the heater 30. In the same vicinity of this drum holding device 220, a waste storage unit 32 is arranged to surround the drum holding device 22. The inner part of this waste/membrane part 32, which is opposed to the outer circumferential layer of the drum-conducting elastic base 28 held by the drum holding device 22, has a plurality of waste ejection holes 34 and is under heavy pressure. electric current that enables discharge by applying),
It also serves as 1 construction i36. The gas introduction section 32 is configured such that the amount of gas introduced into the vacuum chamber 14 by the pulp 38 outside the vacuum chamber 14 through a pipe is adjusted. It is a power source.

In such a q-forming device, a sludge containing Si atoms in the true temperature 1p4, for example 5il14°Si2H, is used.
6. Introduce the raw material scraps of SiF4 bone into the vacuum chamber 14 from the gas introduction part 32, and adjust the exhaust so that the ik force in the vacuum chamber 14 is 0.1 to I Torrf 4 degrees. Then, the frequency is adjusted by the power source 40. 13.56 MHz same frequency rJj1. By applying power between the electrode 36 and the conductive carrier 28, raw material waste is separated and amorphous silicon is deposited on the surface of the tetraelectric carrier 28.

In this case, amorphous silicon has the periodic table fil, a
By doping the elements in the group Va and the group Va, the 1dli'jK child resistor has a high resistance, and the specific resistance 1i
tlJ uTu is also possible (resistivity decreases due to aggressive doping)0 Also, the resistivity can be increased by adding nitrogen, carbon or oxygen atoms.

The doping method is to supply the raw material gas from the gas station 32 to the vacuum chamber 14 K4! 'f, besides entering, at the same time,
Doping or 6≦additional scum'k −
In this case, if the atoms to be doped or traveled are excited by electromagnetic waves such as microwaves, the doping efficiency can be improved and the I It is a fish of 1 tan and is very active.

Now, an experimental example in which a non-inventive photovoltaic member was formed into a film using such a 44-layer manufacturing apparatus will be described below.

<Implementation 1>l> Here, an example will be described in which Seijo Denyo Seikosha A11 Pekotodo is installed.

First, in the vacuum chamber 14, Blt8. ) SiH4 gas is used as the gas, but at the same time, 82H6 gas is used at an inflow rate of 0.01 to 1 inch for the inflow rate of Sil[4, and CH4 gas is used at a vIL level of 10 to 100%. In dedication,
Introduce each. Then, the inside of the vacuum chamber 14 is set to 0.
Film formation was carried out for 15 minutes while maintaining the pressure at 5 Torr, 11 mica, and applying an applied core force of 200 W. Then, the mass flow controller is controlled by a microcomputer to control the flow of B2 gas for 5 minutes.
C
The I-I 4 dregs were each reduced exponentially to 0 (ratio).

The barrier layer 3 is likely to be formed at 11 fJ during the film formation at 1::41 for 20 minutes up to this point. Leave this state (B2H6
The gas flows in with a slight J+, and the inflow of CH4 gas is O)
, and a further 2 hours of preparation. The photoconductive layer 4 is formed by this two-hour film formation. Next, the application of frequency power was analyzed once, and then 5i was applied for 10 minutes.
Inflow of B2H6 gas for I>iTh population of l-14 scum: A is 0. CH4 dregs inflow ratio χ is 100 to 500
%, apply high frequency force for the last minute and perform Sei 1 Riku. By this film formation, the surface 4J,
The base layer 5 is completely formed.

Note that B 2 H6 scum was used at a high concentration (2oooppm) and at a low concentration (20PPm), and the former was mainly used for forming the barrier layer 3 and the latter was mainly used for forming the photoconductive layer 4. Involved.

As shown above, the relationship between the flow rate of each gas and the film formation time is as follows:
It will look like Table 1.

Further, FIG. 3 shows how the flow rate of waste changes over time.

In FIG. 3, the horizontal axis shows time, and the vertical axis shows gas flow rate. In the figure, the purge between 140 minutes and 149 minutes is
It shows the time during which gas is exhausted without film formation.

Note: IT is time (minutes) 2, reaction pressure is 0.5 Torr 3, power is 200 W for high frequency 1 (however, 140 minutes to 14
Application was interrupted for 9 minutes) The electrophotographic photoreceptor produced in this way had no film peeling, and when charged using a corona discharger, the charge flowing from the charger to the photoreceptor was 0.4 μC/2. Surface potential 4 under the condition of
00v was obtained.

Conventionally, this type of photoreceptor has a developing bias of 200
There were parts where dielectric breakdown occurred when the voltage was set to about V, but
In the photoreceptor described above, no dielectric breakdown occurred even when a developing bias of 100V was applied. This is important when a reversal development method is used, such as in a laser printer.

Furthermore, it was confirmed that even when the above-mentioned photoreceptor was set in a well-known electronic copying machine and used repeatedly for 1 million copies, good images were obtained and the photoreceptor had a sufficiently long life.

<Example 2> Here, in the photoreceptor shown in FIG. ) iJq amorphous silicon carbide. The specific resistance of the first barrier layer 3a is lO0cm
The resistance of the second barrier layer 31 is approximately 10 Ω. The first barrier layer 3a prevents carriers from flowing from the support 2 to the leading central layer 4, and
The barrier layer 3b is formed by this first μ1. '(It assists the carrier blocking function of the wall layer 3b.

In this case, the first barrier layer 3a prevents carrier injection from the supporting body 2, and at the same time allows the carriers generated in the photoconductive injection layer 4 to flow out to the side of the supporting body 2. To child 4, !: is done. Therefore, in this example, B
Since K is doped, the specific resistance is not as high as K as described above. Therefore, the second barrier layer 3b does not have a partial voltage.''In the case of ``Rulare'', the photoquaternary conductive JV! A partial pressure is applied at the interface with 14, and there is a risk that the charge retention ability or the wire reciprocity may be lowered. Therefore, in this example, these problems are improved by inserting a second barrier layer 3b, which has a resistivity similar to that of the first barrier layer 3a, at the interface. SiH4 as gas
Introduce gas. At the same time, with respect to the inflow J1 of SiH4 gas, B2H6 gas is added in a range of 0.01 to 1 cm.
H4 gas is added in a range of 10 to 100%, the pressure inside the vacuum chamber 14 is set to 0.5 Torr, and high frequency power of 200 W is applied to form a film for 5 minutes. Next 5
Film formation was carried out for 5 minutes while decreasing the amount of B2H6 residue exponentially so that the ratio to the amount of SiH4 gas ηε was 1X10' to 1×1O or less.

At this time, CH4 gas is introduced at a constant amount of 508 CCM.

By forming the film for a total of 10 minutes, the first barrier 1
m3a is formed. During the next 10 to 20 minutes, film formation was performed for a total of 10 minutes while decreasing the inflow amount of CH4 gas in an exponential manner for the remaining 5 minutes. As a result, the second barrier layer 3b was formed. Continued further, 2
Film formation for forming the photoconductive layer 4 was carried out for a total of 2 hours from 0 minutes to 140 minutes. In this case, the vacuum chamber 1
In addition to the SiH4 gas as a raw material gas, B2H6 gas of low 1jS U is introduced into 4, and the application of high frequency power from the source 40 is temporarily interrupted.
In the remaining υ10 min 1 h], the ratio of the inflow amount of B2H6 sludge to the inflow amount of SiH4 sludge is 0, CI-1
These gases were introduced so that the amount of inflow of the four gases was 100 to 500 cm, and film formation was performed by applying high frequency power only for the last minute. As a result, the surface coating layer 5 was formed.The photoreceptor thus formed had no peeling, and under the same conditions as in Example 1, the surface coating layer 5 was
v was obtained.

Furthermore, the withstand voltage against developing bias was 1500 V or more, which was superior to Example 1. Furthermore, the life span was the same as in Example 1. Table 2 shows the relationship between the inflow amount of scum and the film forming time in Example 2.

Further, as in Example 1, the temporal change in gas inflow amount is shown in FIG. 4.

Figure 4 shows the above-mentioned temporal changes in the same writing system as Figure 2J3.0Left below margin〈Example 3〉Here, SiH4 gas was diluted to 101% using hydrogen scum and the raw material The film was formed using the same conditions as in Example 1 except that the film was used as a residue.

As a result, the same results as in Example 1 were obtained regarding the surface paper level and 1ili'l'lE.

However, when X-ray diffraction measurements were performed, it was confirmed that under conditions where a large amount of hydrogen is contained, such as on the actual flow side, there are crystallized portions.

When we investigated the spectral sensitivity characteristics, we found that the long wavelength side (80
It was found that the photosensitivity extended to 0 mm). This is a suitable condition for an electrophotographic photoreceptor when imaging is performed using a semiconductor laser. In addition, in Table Fan Example 2, although a P-type semi-core was used as the second barrier layer 3b, an explanation can be given as to why this portion was not simply made into a sieve resistance layer.

FIG. 5 shows a first barrier layer that is a P-type half-barrel layer on a support, a second barrier layer that is an insulating layer that is based on /lico/ atoms and contains C1O or N, and an amorphous layer that contains hydrogen. This is made by laminating a photoquadruple layer made of high quality silicon and a surface coating layer on a J-wall.
(0 which is an energy band diagram of the Oji photo sensitive element) Furthermore, FIG. 6 is an energy band diagram of Length 11 Example 2 of the present invention.

In both cases, the positive band is the photoreceptor.

In FIG. 5, when the support side is grounded and the surface of the surface coating layer is positively charged, light is irradiated from the surface coating layer side, thereby generating carrier pairs of electrons and holes. . Among the generated carriers, electrons are attracted to the surface coating layer side and neutralize the positive charge on the surface,
Holes are attracted to the support side. However, electrons flow in from the support side, but they are diblocked by h>1 and the second barrier layer.

Now, as is clear from the energy band diagram of FIG. 5, the second barrier layer prevents carriers (holes) originally generated in the volatile layer from flowing out to the support. As a result, the residual potential of the photoreceptor increases. Furthermore, fatigue development of the photoreceptor occurs, and clear images cannot be obtained when such a photoreceptor is used.

On the other hand, in the case of the present invention, as is clear from [C6], the gearia (holes) generated in the light guiding layer
The above-mentioned problem does not occur because the two barrier layers do not impede the passage of the signal.

〔Effect of the invention〕

As described above, the invention uses an amorphous semiconductor layer that dissolves impurities as a barrier layer, and continuously changes the impurity concentration at the interface between the layers.

Therefore, film peeling does not occur due to differences in strain between the layers.

In addition, by selecting an element to be layered in group III a or group Va as the impurity doped in the ←rrt 1 layer, it is possible to select a p-type or n-type for positive charging or negative charging, depending on the application. can be conductive type (1st ia
An example of a group element is B, and an example of an element of a group is PCIJ).

Furthermore, by adding an atom of N, C, or O as an impurity, the resistivity can be increased to 1 lilJ III
can do.

In addition, as a barrier layer, a 21iff portion is provided, including a portion facing the support side and a portion facing the photoconductive layer side, and by increasing the specific resistance of the former and the latter, a photoconductive layer with excellent withstand voltage is provided. A member is obtained.

Further, by providing a partially crystallized layer, photosensitivity to long wavelength light is improved.

Furthermore, by covering the surface of the photoconductive layer with a top layer, charge retention and mechanical strength can be improved.

In addition, half /j' as a barrier layer is added to the body layer with valence electrons 11i1
1 In addition to impurities (elements belonging to Group 111A or Group Va), in particular, Cf:g->: Comparing to the case where this layer is made into a mere semi-quartet layer by cooling. Therefore, in addition to improving charging ability and charge retention ability, there is an advantage that breakdown voltage is significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a 191-plane view of an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the manufacturing apparatus of the electrophotographic photoreceptor on the same side, and FIGS. 3 and 4 explain the manufacturing method on the same side. Explanatory diagram for, 5th
6 and 6 are energy band diagrams for explaining the ipsilateral effect. 1... Photoconductive member (electrophotographic photoreceptor), 2... Support, 3... Barrier layer, 4-layer photoconductive layer, 5... Surface wave Q layer. Agent: Patent attorney Noriyuki Chika (and 1 other person) jI1 figure procedural amendment (voluntary) 1930 Italy 2. υγ Japan Patent Office Commissioner 1, Indication of the case, Patent Application No. 58-3302J8 2, Name of the invention Photoconductive member 3, Relationship with the person making the amendment Patent applicant (307) Tokyo Shibaura Electric Co., Ltd. 4, Agent T'lOO Tokyo Shibaura Electric Co., Ltd. Tokyo Office 6, 1-1-6 Uchisaiwai-cho, Chiyoda-ku, Tokyo Contents of amendment (1) "..." on page 4, line 15 of the specification.・
It says that the potential pattern is a shape.
"The charge pattern is the shape," he corrected. (2) From the last line of page 7 to the first line of page 8 of the specification, “...
・・・・・・Group 11a elements・・・・・・・・・Each becomes an n-type semiconductor・・・・・・・・・” is replaced with [・°°°゛... (II group a element or group V element)
By doping with group a elements, it becomes a p-type or n-type semiconductor, respectively.''that's all

Claims (1)

[Scope of Claims] (1) a 1st + 7) layer having conductivity, a second layer made of an amorphous semicircular body that prevents the inflow of carriers from the first layer, and a second layer having photoconductivity. 3 layers in this order, the second layer contains an impurity, and has a portion near the interface of the second layer where the impurity concentration continuously changes. Photoconductive member. (2) The photoconductive member according to claim 12fl, paragraph 1, 6, 1, wherein the impurity is at least one element belonging to group 1IIa or group Va. 13) The photoconductive member according to claim 2', wherein the impurity further contains at least one element selected from among nitrogen, carbon, and oxygen q. (4) The second layer has two types of parts containing amorphous silicon and having different resistivities, and the first of these two types of parts
Claims 1, 2, or 3, characterized in that the specific resistance of the portion facing the 30th layer side is lower than the specific resistance of the portion facing the 30th layer side. The original? 4
Electrical parts. 15) Claim 1, characterized in that at least one or more of the second layer or the third layer is made of a material made of silicon atoms existing in the crystallized portion as a base material. 3. The photocolumn 7 electric member according to any one of Items 1, 2, 3, and 4. (6) a first layer having conductivity; a second layer made of an amorphous semicircular body that prevents the inflow of carriers from the first layer;
It has a third layer having photoconductivity and a fourth layer covering the surface of the third layer in this order, and at least one layer of the second layer or the Sα40 layer contains impurities. A photoconductive part 4 is characterized in that a portion containing impurity and in which the concentration of the impurity changes continuously is placed near the interface of the layer containing the impurity (the impurity is the first [a]). The light guiding member 1d according to claim 6, characterized in that it is at least one element belonging to Group Va or Group Va, and at least one element among nitrogen, carbon, and oxygen. (8) Second Claim 6, characterized in that at least one or more of the layer, the third layer, or the fourth layer is made of a material based on silicon atoms in which a crystallized portion exists. The photoconductive member according to any one of Item 7.