JPS6261056A - Photoconductor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to light (here, light in a broad sense, visible light, X-rays, ultraviolet light, etc.) used in charge accumulation mode.

It relates to a photoconductor that is sensitive to electromagnetic waves (including infrared rays, etc.) and is used in electrophotographic devices and other imaging devices.

Conventional technology As a photoconductor in image pickup tubes, solid-state imaging devices, or photosensitive members for electrophotography used in charge accumulation mode, it has high photosensitivity, non-pollution, and high hardness.
BACKGROUND ART Amorphous silicon (hereinafter referred to as a-8t) containing 40 atm % of hydrogen as a modifier for reducing the localized density of states has attracted attention and is used as an electrophotographic photosensitive member.

However, the electrophotographic photosensitive material made of the above a-8t has poor overall characteristics such as dark resistance, photoresponsiveness, low charging potential due to charge accumulation, and usage environment characteristics such as moisture resistance. Improvements in characteristics are still needed.

For example, the first problem is that an electrophotographic photoreceptor using a-8i as a photosensitive member has problems with an organic photoconductor (
(hereinafter referred to as oPC) or has a thicker dielectric constant than Se ((OPC: ~3. Se: ~6. a-3i
:~11) Since the capacitance is large, a large charging current is required when charging the surface. For this reason, other electrophotographic photoreceptor materials (OPC).

Currently, it is necessary to use a surface potential that is lower (about 400 V) compared to 600 to 800 V for Se, etc. This also means that, for example, in a typical electrophotographic copying machine that uses a two-component developer, it is difficult to continuously produce images with high saturation density, especially when copying images using toner with an appropriate amount of charge. It is difficult to obtain it stably.

Furthermore, in terms of photosensitivity characteristics, a photosensitive member with a large capacitance has a large amount of surface charge, and in order to lower the surface potential, it produces more photons than a photosensitive member with a small dielectric constant.
n) and has many practical disadvantages.

Next, the second problem is that when adding oxygen, carbon, nitrogen, etc. to a photoconductive member in order to increase its resistance and improve its surface potential, conventionally, a large amount of residual potential is generated during use, and There have been problems such as a ghost phenomenon occurring due to accumulation of fatigue during use or deterioration of photoresponsiveness.

Furthermore, as a third problem, depending on the structure of the photosensitive member, images may become blurred at high temperatures and high humidity, which cannot be ignored.

As a means for reducing the first capacitance, Japanese Patent Laid-Open No. 54
JP-A-143645 discloses a functionally separated type photosensitive member using an organic semiconductor material, and JP-A-66-24355 discloses a functionally separated type photosensitive member using an inorganic semiconductor material.

Problems to be Solved by the Invention If the former organic semiconductor material is used, it will not function as a long-life photosensitive member that takes advantage of the high hardness characteristic of A-8i, so it cannot be said to be an effective means.

In addition, since the latter is a chalcogen material that tends to be polycrystalline or a material with a high relative dielectric constant (~1o for SiC), even if an improvement in charging voltage is expected by using a material with a large specific resistance, the second Problems such as an increase in residual potential were not solved, and a-St's characteristics of long life, high sensitivity, and low residual potential remained, and it did not have a high charging potential or fast photoresponsiveness. It is impossible to obtain a photosensitive member having a structure in which a charge generation layer that generates movable carriers by lightning excitation and a charge transfer layer in which the carriers are efficiently injected and effectively transported,
The charge transfer layer has germanium nitride as a main component.

Function Germanium nitride has an optical bandgap width of 1.3 to 3.3, depending on the nitrogen composition ratio. Despite the large change in OeV, it exhibits n-type conduction. In addition, even in materials with such a large optical bandgap, the activation energy is O,S~0.9e.
Since V is small and electron mobility is high, a good photosensitive member can be easily obtained by controlling the width of each optical band gap so that electrons can be efficiently injected from the charge generation layer into the conduction band of germanium nitride. It will be done. In addition, the dielectric constant of germanium nitride has an optical bandgap width of 1.6 to 3*O
e V material and small at 4 to 8.

By using such germanium nitride as a charge transfer layer in a photosensitive member, a-8i or a-G
Even if a photosensitive layer with a large dielectric constant such as O is used as a charge generation layer, a photosensitive member with a small dielectric constant as a whole can be changed,
A photosensitive member with practically high photosensitivity and high surface potential can be obtained.

Example nitride gel ff 2, -m (hereinafter a-Ge1-xN,
(denoted as 0 x 1), which refers to a film containing hydrogen or halogen atoms), GeH4, Ge2H6゜Ge
3H8, GeF4. GeHF3. GeHCl3. GeH
3F.

GeCl4. GeHCl3. GeH2C12, GeHC
l3N2. NH3, H2NNH2, NH3, NH4N3
．． Plasma CVD method using raw material gas of N atoms such as F3N, F4N2, anti-Ar, H2, N2. A reactive sputtering method in NH3 or a reactive vapor deposition method may be used. Moreover, a-8t as a photoconductive layer is SiH4,5i2H,,5t3H8,5
tF4゜SiHF3,5tH2F2,5tH3F,5i
C14,5tHC13゜S 1H2C12,S 1H3
Raw material gas of St atoms such as C1 or these gases are converted into N
Plasma CVD method using a gas diluted with a gas such as 2 y A r p He or using St as a target,
It can be formed by a reactive sputtering method or a reactive vapor deposition method in Ars HR. Amorphous germanium (hereinafter a-Go)
) is the raw material gas for the Go atoms mentioned above; b is plasma CVD1 using these gases diluted with N2 s Ar + He, etc. or reactive sputtering in Ar s N 2 with Ge as the target. Similarly, a-5iGe is formed using a mixed gas of the above-mentioned Go atom source gas and 81 atom source gas, or
Plasma CVD method using gas diluted with gas such as N2, Ar, He, etc. or Si and G
It is formed by a reactive sputtering method or a reactive evaporation method using a mixed target of O or two targets of Si and Go.

Examples 1 and 2 below will be described using a reactive sputtering method, and Examples 3 and 4 will be described using a plasma CVD method.

Example 1 A description will be given with reference to the cross-sectional view of the photoconductor of this example shown in FIG.

A mirror-polished aluminum (At) substrate 11 was placed in a magnetron sputtering device, and after exhausting to 2×1 O −6 Tort or less, the substrate temperature was raised to 260° C. Targeting Go polycrystal, Ar at 1-3 mTorr,
Introduce N2 into the 2~e mTorr device and set the frequency 1
3.56MHz high frequency power 300~500W,
The charge transfer layer a-Gth, -dNx layer 12 is
A thickness of 5 μm was formed. Subsequently, Ar was applied at 1 to 10 mTorr.

N2 was introduced at 0.3 to 4 mTorr, and an A-31 layer 13 having a thickness of 1 μm as a charge generation layer was formed using a polycrystal as a target at a discharge power of 200 to aoow.

At this time a-Go, -! The dielectric constant of the N layer 12 is 6 to 7.
The a-8L layer 13, which is a charge generation layer, had a molecular weight of 10 to 11. Furthermore, when the photoconductor characteristics of the photoconductor having the structure shown in FIG.
An electrophotographic photoreceptor with a low residual potential and a very high potential acceptability of 1 sV or less was obtained.

However, in a photoreceptor having such a photosensitive layer formed on its surface, the charging potential tends to decrease in proportion to repeated charging. This is considered to be because surface oxidation of a-3L in the photosensitive layer on the free surface progresses rapidly due to the influence of ozone, etc., and the trap level in the oxidized layer promotes the injection of charges on the surface.

Therefore, as shown in FIG. 2, a new surface layer 14 is formed on the free surface of the photosensitive layer, 5t1-, N, , 5t1-xC,.

ae, -xC,, A11-xO,, A11-xN! ,
(By forming a layer such as 0(x(1)a-C:H (amorphous carbon) with a thickness of 0.06 to 1 μm, changes in the charging potential can be reduced, and the "blurring" of images at high temperatures and high humidity can be reduced.) ” could be prevented from occurring.

Example 2 An image pickup tube target in this example is shown in FIG. I
A glass substrate 31 with an rO transparent electrode 3o formed on its surface is placed in a magnetron sputtering device, and the reference temperature is set to 250°C.
G@polycrystalline target at °C, Ar: 1-3m
Torr, N2: 2-6mTorr, discharge power 3
Three threshold a-Ge 1-xNx layers 32 were formed at 00 to 500W. Next, using 83 polycrystal as a target, Ar: 1
~10 mTorr, 20 ppm concentration of B2H6:0 diluted with hydrogen, 3-0.4 mTorr, discharge power 2oo~5ooW, B doped a-8L layer 33
was formed to a thickness of 0.5 μm, and then a 5B283 layer 34 was deposited to a thickness of 0.1 μm as an electron beam Rande ink layer to fabricate an image pickup tube target.

At this time, the dielectric constant of the a-Go 1-8Nx layer was small, 4 to 5, and that of the a-8i layer was 10 to 11.2. Such an imaging tube had little capacitive afterimage and was capable of extremely good imaging.

In addition, in the photosensitive layer a-3L, B is about 1 to 81.
Contains ~5 ppm, and electrons and holes, which are photoexcited carriers, move efficiently within the layer, and electrons move through the a-G layer, which is a charge transfer layer.
is implanted into the ol-xNx layer 32. The Ge1-rNxN white layer functions as a layer for blocking the injection of holes from the TO side, and even though the optical bandgap is large, the injection of electrons from the a-5i is efficient, and image retention and burn-in are prevented. I was able to get a good image without any issues.

Example 3 An electrophotographic photosensitive member in this example is shown in FIG. A mirror-polished 90φ x 310w A1 drum substrate 4o is placed in a capacitively coupled plasma CVD device with a distance between electrodes of 55 mm, and the inside of the reaction vessel is heated to 5 x 10-6 Torr.
After evacuation, the AI substrate 40 was heated to 150-250°C. GeF4: 1-5 sccm.

After introducing NH3 for 190 to 200 seconds and adjusting the pressure inside the reaction vessel to 0.2 to 1.0 Torr, high frequency power 3 was introduced.
00-80 oW f a-Gol-, Nx layer 41 to 1
5-20 μm formed, GeF: o, 5-10800
m, 5 in 4: 100 to 200 sccm, 5 to 50 sCam of B2H6 diluted with hydrogen at a concentration of 10 ppm was introduced, the discharge power was controlled to 0.2 to 2.0 Torr, and the discharge power was 150 to 200 sccm.
B-added amorphous silicon germanium (
Hereinafter referred to as a-3iGe:H:F) layer 42 is 1 to 3
μm formation followed by Te SiH4: 5-10 sccm,
NH3: 100-200 sacm introduced, pressure 0.2~
1.0Torr, discharge power 150~6oOW Te5i1-
An electrophotographic photosensitive member was obtained by forming 0, 1-0, and 2 prn layers of the electrophotographic layer 44.

This photosensitive member is used by being negatively charged, and its spectral sensitivity is high over a high range of 400 to 850 nm.
a-3iGe:H:F layer 4 compared to a-8i layer
By using No. 2 as a charge generation layer, the photosensitivity was improved to wavelengths in the infrared region, and this photosensitive member was mounted on a laser beam printer using an 800 nm semiconductor laser as a light source, and clear printing was confirmed. a-Ge1 in this case
-! The N layer 41 narrows the optical band gap and has a relative dielectric constant of 7 to 8, and functions not only as a hole blocking layer but also as a laser beam absorption layer, so it is difficult to remove from the AI substrate. This prevents the resolution from decreasing due to reflections.

In addition, a-Ge 1-ENx with a relatively large dielectric constant
There is a tendency for the dark resistivity to be small at room temperature. In this case, it can be increased by adding B or carbon to the a-Ge1-xN process. For example, a -Ge 1-□NX, which has a dielectric constant of 8, is as small as ~109 Ω・ω, but it can be increased to ~1013 Ω・− by adding 10 to 0,01 at m% of C or B, or both. It can be resisted. This further enabled gradation reproduction and printing with excellent halftone reproduction.

Example 4 As in Example 3, a film was formed using the plasma CVD method. The substrate heating was controlled at 160 to 250°C, and as shown in FIG.
0-200 secm, 400ppm diluted with hydrogen
Concentration I) BF3 100-200 gccm, gas pressure 0.2-1, OTorr, discharge power 100-40
P-type a-3t with B added at 0W: H(B)51 at 0.
A thickness of 2 to 1 μm was formed. Then 5in4:10100-2
008c, 40 ppm BF3 diluted with hydrogen at 1
~IQ 800m, gas pressure 0.2~1 *0 Tor
r, type 1 a-3 with B addition at a discharge power of 100 to 40 oW
i: H layer 52 was formed to a thickness of 1 to 2 μm.

Furthermore, GeH4: 1~o, ssccm, N2: 150
:200sccm, gas pressure 0.2-1.0 Torr
An a-Gel-xN layer 63 having a thickness of 10 to 20 μm was formed using a discharge power of 300 to 600 W to form an electrophotographic photosensitive member.

This photoreceptor has a saturation charging potential of 100° to 16° when positively charged.
00V, and when tested by mounting it on a commercially available copying machine, good images were obtained and printing durability of over 50,000 copies was confirmed.

Effects of the Invention The photoconductor according to the present invention uses a-Ge1 as a charge transfer layer.
An electrophotographic photosensitive member used in a charge accumulation mode by using a layer containing -xNx (o<x<1) as a main component;
It is possible to reduce the capacitance of an image pickup tube, etc., and provide an excellent photosensitive member capable of high voltage operation with excellent photoresponse.

[Brief explanation of drawings]

1 is a cross-sectional view of a photoconductor according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view of another example in which a surface layer is further formed on the photoconductor in FIG. 3 is a cross-sectional view of an image pickup tube target in another embodiment of the present invention;
The figure is a cross-sectional view of a photosensitive member suitable for a laser beam printer in still another embodiment, and FIG. 6 is a cross-sectional view of a photosensitive member suitable for positive charging in still another embodiment. 11... Aluminum substrate, 12...
a-Gol, Nx layer, 13...a-3i layer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (5)

[Claims] (1) A charge generation layer that generates mobile carriers by photoexcitation and a charge transfer layer in which the carriers are efficiently injected and effectively transported are laminated on a support, and the charge transfer layer is made of germanium nitride. A photoconductor characterized by having the main component as a photoconductor. (2) The photoconductor according to claim 1, wherein the charge transfer layer contains at least either hydrogen or halogen atoms. (3) The photoconductor according to claim 1, wherein the charge generation layer is mainly composed of amorphous silicon containing at least either hydrogen or halogen atoms. (4) The photoconductor according to claim 1, which has a charge injection blocking layer between the photoconductor and the support. (5) The photoconductor according to claim 1, which has a surface coating layer on the free surface of the photoconductor.