JPS6273275A - Photoconductive body - Google Patents

Abstract

PURPOSE:To obtain the titled body having a low dark current and a low operating voltage by constituting the titled body from the 1st layer composed of one of 3 kinds of specific films or a combination thereof and the 2nd layer mainly composed of a germanium nitride provided on at least one of the interfaces of the 1st layer. CONSTITUTION:The titled body is prepared by forming the 1st layer of any one selected among the film mainly composed of the noncrystalline silicon contg. a hydrogen atom or a halogen atom, a film mainly composed of a noncrystalline silicon and germanium, and a film mainly composed of a noncrystalline germanium or the combination thereof, and the 2nd layer mainly composed of the germanium nitride provided on at least one of the interfaces of the 1st layer. For example, the 2nd layer of GeNx is prepared by using a polycrystalline of Ge as a target, and introducing 1-3mTorr an Ar gas and 2-6mTorr an N2 gas into an apparatus, and by impressing a high frequency electric power of 300-500W. The 3rd layer of a-Si:H is prepared by using a polycrystalline of Si as a target, and by introducing 1-10mTorr an Ar gas and 0.3-4 mTorr H2 gas into an apparatus, and by impressing a discharge electric power of 200-800W. Further a transparent electrode 4 composed of ITO is formed by a sputtering method.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a photoconductor composed of an amorphous material containing silicon atoms or germanium atoms as a main component and germanium nitride.

(Prior art) Amorphous silicon hydride (hereinafter abbreviated as a-8iH) has excellent photoconductivity and heat resistance, and is also non-polluting, so it has been researched and developed for use in imaging devices and electrophotographic photoreceptors. Active. A blocking structure in which a charge injection blocking layer is formed at the interface of a photoconductive layer is effective as a method for realizing the high sensitivity and low dark current required for these imaging devices. For example, in the case of a hole blocking layer that prevents holes from flowing into the photoconductive layer, oxides such as At205 and 5iOX, and organic polymers 5INx such as polycarnate have been proposed.

(References: JP-A-56-24356, JP-A-57-
No. 581.61) (Problem to be solved by the invention) The hole blocking layer is replaced with conventional 5iNX, SiOx, A
When composed of T206 and organic polymers, it also forms a barrier against electrons in the photoconductive layer, causing problems in reducing operating voltage (reducing afterimages in imaging devices and electrophotographic photoreceptors). .

SUMMARY OF THE INVENTION An object of the present invention is to provide a photoconductor which eliminates the conventional drawbacks, uses a layer containing germanium nitride as a main component as a hole blocking layer, and enables low dark current and low operating voltage.

(Means for Solving the Problems) The photoconductor of the present invention includes a film mainly composed of amorphous silicon containing hydrogen atoms or halogen atoms, a film mainly composed of amorphous silicon germanium, and A first layer consisting of any one of films mainly composed of amorphous germanium or a combination thereof, and a second layer mainly composed of germanium nitride on the interface of at least one of the first layers. It forms a layer of

Further, the first layer contains any one of oxygen atoms, nitrogen atoms, and carbon atoms, or a combination thereof, and the first layer contains at least one boron atom or phosphorus atom. The second layer of germanium nitride contains one or both of oxygen atoms and carbon atoms, and the second layer of germanium nitride contains oxygen atoms, carbon atoms, or both. on the other interface of the layer of
Amorphous silicon containing silicon nitride or boron and containing at least hydrogen atoms or halogen atoms;
Either one of amorphous silicon germanium and amorphous germanium is formed.

(Function) Because germanium nitride exhibits n-type conductivity regardless of the nitrogen composition ratio, it prevents holes from flowing into the amorphous silicon that is the photoconductive layer, and also prevents the electrons in the amorphous silicon from flowing into the amorphous silicon. Since a barrier is often formed, the dark current decreases and the operating voltage decreases. Furthermore, even when the photoconductive layer is composed of amorphous silicon germanium, which has a narrow bandgap, or amorphous germanium, it is possible to inhibit germanium nitride by reducing the nitrogen composition ratio of vacated germanium. Since it is easy to reduce the band width, germanium nitride acts effectively as a hole blocking layer, achieving the same effect as when the photoconductive layer is made of amorphous silicon.

(Example) An example of the present invention will be described based on FIGS. 1 to 5.

GeH4, Ge2H6, Ge6H8, GeF4, G
eHF3, GeH2F2, GeHsF, GeC
Z, s, Ge HCLs, GeH2Ct2, Ge
Ge atom source gas such as H3CI-, G e F 2 , Ge CZ2 and N2, NH3, H2NNH2
, HN3, NH4N3, F3N, F4N2, etc., and the target is Ge or Ge 5N4, Ar, H2, N2, N
A reaction scattering method in H6 or a vapor deposition method is used. Moreover, the amorphous silicon of the photoconductive layer is S r H4,
S i2 Ht,, S 13 Ha, S t F 4,
S t HF s, SiH2F2, SiH3F, 5
ict4, S I HCLs, 5iH2Ct2, S 1
Plasma CVD method using a raw material gas of St atoms such as H3CZ or gas diluted with gas such as H2, Ar, He, etc., or reactive sputtering method or vapor deposition in Ar or H2 using St as a target. It can be formed by law. Amorphous germanium is produced by using the above-mentioned Ge atom raw material gas or by combining these gases with H2, Ar, or He.
Plasma CVD method using gas diluted with
A2 targeting Ge, reactivity in H2 A?
It can be formed using the vine ring method or vapor deposition method. Amorphous germanium can be produced using a plasma CVD method using a raw material gas of Ge atoms or a raw material gas obtained by diluting these raw material gases with N2, Ar, He, etc., or by using an A method using Ge as a target.
r, is formed by reactive sputtering or vapor deposition in N2, and amorphous silicon germanium is similarly formed by Ge.
Plasma CVD method or St
and Ge mixed target or 2 of Sl and Ge
It is formed by reactive sputtering or vapor deposition in Ar or N2 using a single target.

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

Example 1 FIG. 1 is a sectional view of a photoconductor of the present invention. In the figure, a mirror-polished At substrate 1 is placed in a magnetron sputtering device, and after exhausting to 2×10 Torr or less, the substrate temperature is raised to 250° C. Targeting Ge polycrystal, Ar: 1 to 3 mTor
r, N2: 2 to 6 mTorr was introduced into the device, and a high frequency power of 300 MHz with a frequency of 13.56 MHz was applied.
A GeNx layer 2 having a thickness of 0.2 μm is formed by applying 500 W to 500 W.

Then Ar: 1 to 10 mTorr, N2:
Introducing 0.3 to 4 mTorr, targeting St polycrystal, and discharging power of 200 to soow.
8t: H layer 3 is formed to have a thickness of 8 μm. Furthermore, an ITO transparent electrode 4 is formed by a sumi9 tuttering method.

Figure 3 shows the voltage dependence of the dark current and the photocurrent for light with a wavelength of 435 nm when voltage is applied so that the substrate 1 is positive and the upper ITO transparent electrode 4 is negative as shown in Figure 1. show. As shown in FIG. 2 as a conventional example for comparison, Ar: 2 to 4 mTorr.

N2: S manufactured at 1 to 2 mTorr with St polycrystal as a target, discharge type, and power of 300 to 500 W.
FIG. 3 shows the voltage-current characteristics in a structure using iNxNSO2, 2 μm, as a blocking layer. As is clear from the figure, the embodiment of the present invention has low voltage operation, high sensitivity,
Moreover, it has a low dark current.

SiNx works as a hole blowing layer like GeNx, but it acts as a barrier to the electrons in a-8t:H, and the operating voltage is higher than that of GeNx, which does not create a barrier. There is.

In addition, the photoconductor shown in Figure 1 was replaced with an electrophotographic photoreceptor (I
When used with negative charging (with the TO transparent electrode 4 and external circuit removed), the saturated surface potential was 440 V and the residual potential was 5 V or less. It can be seen that the examples of the present invention provide an electrophotographic photoreceptor with a large charge acceptance capacity and a small residual potential.

Embodiment 2 FIG. 4 is a sectional view of a photoconductor according to a second embodiment of the present invention. In the figure, a glass substrate 11 with an ITO transparent electrode 10 formed on its surface is placed in a magnetron sputtering device, a Ge polycrystalline target is set at a substrate temperature of 250° C., Ar: 1 to 3 mTorr, N2:
2 to 6 mTorr, discharge power 300 to 50
At 0W, the GeNx layer 12 is formed to have a total thickness of 1200 to 3000X. Next, using St polycrystal as a target, Ar: 1 to 10 mTorr, B2H diluted with hydrogen at a concentration of 20 ppm: 0.3 to Q, 4 mTorr,
Boron-doped a-8 with discharge power of 200 to 800 W
t: H layer 13 is formed to a thickness of 2 to 3 μm, and then A
r: 1 to 3 mTorr, N2: 2 to 5 mTorr, S at discharge power 300 to 500W
1000 to 3000 iNx layers 14 are formed. Furthermore, the electron beam landing layer 5b2S315 is
An image pickup tube target is manufactured by OX vapor deposition. Since the ITO electrode 10 is positively biased with respect to the cathode 16, electron-hole pairs generated by incident light from the glass substrate 11 side are separated by the electric field in the film. Holes are lifted into the boron-doped a-8t:)I layer 13 to the upper surface, and electrons are collected at the lower ITO transparent electrode 10. The SiNx layer 14 has a large X value, allows holes to travel easily, and acts as an electron blocking layer, and the GeNx layer acts as a hole blocking layer. In addition, by adding boron, Ja-8t:H layer 1
The holes in 3 become more mobile. Therefore, in this embodiment, the operating voltage is low, and good characteristics with little burn-in and afterimage can be obtained.

Embodiment 3 FIG. 5 is a sectional view of a photoconductor according to a third embodiment of the present invention. In the figure, a mirror-polished AA drum 20 is placed in a plasma CVD apparatus using a capacitive coupling method, and after the inside of the reaction vessel is evacuated to 5×10 Torr or less, the substrate is heated to 150 to 250° C.

GeF: 1 to 5 secm -NHs: 190
~200 BCQm is introduced, and the pressure inside the reaction vessel is reduced to 0.
After adjusting to 2 to 1.0 Torr, the GeNx layer 21 total 212 to I 11 is heated with high frequency power of 300 to 800 W.
m formed, Ge F4; 0, 5 to 10 sec,
5jH4: 100 to 200 Beam, 10 ppm concentration of PH3 diluted with hydrogen: 5 to 10 se
A phosphorus-doped amorphous silicon dalmanium layer 22 of 1 to 3 μm is formed at 0.2 to 2.0 Torr and a high frequency power of 150 to 500 W, and then
IH4: 100 to 200 sec, 0.2
Or 2. Under the manufacturing conditions of Q Torr and high frequency power of 150 to 500 W, the a-8t: H layer 23 is
to 15 μm. Furthermore, 5IH4: 5 to 10 sec, NH3: 100 to 200 s
ECM is introduced, and the SINX layer 24 is heated at a pressure of 0.2 to 1 and a Q Torr discharge power of 150 to 600 W.
000 to 2000X formation to obtain a photoconductor.

The spectral sensitivity of this photoconductor when negatively charged is high over the range of 400 to 85 Q nm, and the a-8i
It was confirmed that the addition to the H layer 23 improved the photosensitivity in the infrared region. This photoreceptor was mounted on a laser beam printer using an 800 nm semiconductor laser as a light source, and clear printing was confirmed.

In this case, the forbidden band width on the GeNXNX layer is narrowed, and it not only functions as a hole blocking layer, but also acts as a laser beam absorption layer, reflecting the laser beam on the surface of the AA drum 20 and improving the resolution. is prevented from decreasing. Furthermore, in order to stabilize the photoreceptor and increase its resistance, an amorphous silicon germanium layer 22 and a-8t:
Carbon atoms, oxygen atoms, or nitrogen atoms may be added to the H layer 23, and the GeNx layer 21 and the At drum 20
In order to improve adhesion to the GeNx layer 21, oxygen atoms or carbon/carbon atoms may be added to the entire GeNx layer 21.

Example 4 5IH4:]00 was deposited on an At drum heated to 15° to 250°C by the plasma CVD method in the same manner as in Example 3.
~200sccm, 40 ppm concentration BF3 diluted with hydrogen: 100~200sec, gas pressure 0
．． 2 to 1. OTorr, a boron-doped P-type a-8t:H film of 0.2 to 1.0 μm was formed at a discharge power of 100 to 400 W, and further 5IH4: 100 to 200 sec, hydrogen diluted to 40 ppm,
Concentration BF3:1 to 1Qsccm.

Gas pressure 0.2 to 1.0 Torr, discharge power 1
A-8T:H film doped with boric acid at 00 to 400W
The thickness is 0 to 20 μm. Furthermore, GeHa: o
, 5 to 1.0 sec, N2: 150 to 200 sec, gas pressure 0.2 to 1.
OTorr, GeN with discharge power 300 to 600W
An x layer of 100 to 5000 x is formed to obtain an electrophotographic photoreceptor.

When this electrophotographic photoreceptor was installed in a commercially available copying machine, it was confirmed that it could print 500,000 sheets with positive charging and produce good images.

(Effects of the Invention) The photoconductor according to the present invention has a low dark current and a low operating voltage, and can be used as an electrophotographic photoreceptor. In particular, when used as a photoconductor for laser beam printers, by reducing the forbidden band width of GeNx, it not only acts as a hole blocking layer but also effectively absorbs laser light, so it has no practical effect. It's a dog.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a photoconductor according to an embodiment of the present invention;
Fig. 2 is a cross-sectional view of a conventional photoconductor, Fig. 3 is a diagram showing the voltage dependence of dark current and photocurrent, and Fig. 4 is a cross-sectional view of a photoconductor according to the present invention. FIG. 5 is a sectional view of an example of application of the photoconductor to an electrophotographic photoreceptor according to the present invention. 1 ・At substrate, 2, 12, 21... GeNX layer, 3
．． 13゜23-a-8t: H layer, 4, 10-IT
O transparent electrode, 5°14.24...5iNX layer, 11.
...Glass substrate, 15...Sb2S3 layer, 16...
Can-P122...Amorphous silicon germanium layer. Figure 1 Figure 2 Figure 3 Plan νdo d Tatsuhiro (Vl

Claims (5)

[Claims] (1) Any of the following: a film mainly composed of amorphous silicon containing hydrogen atoms or halogen atoms, a film mainly composed of amorphous silicon germanium, and a film mainly composed of amorphous germanium. A photoconductor characterized in that a first layer consisting of one layer or a combination thereof and a second layer containing germanium nitride as a main component are formed on the interface of at least one of the first layers. (2) The photoconductor according to claim (1), wherein the first layer contains any one of oxygen atoms, nitrogen atoms, and carbon atoms, or a combination thereof. . (3) The first layer contains at least one boron atom or phosphorus atom.
A photoconductor according to claim (1) or (2), characterized in that the photoconductor contains: (4) Any one of claims (1) to (3), characterized in that the second layer of germanium nitride contains one or both of oxygen atoms and carbon atoms. 1. The photoconductor according to claim 1. (5) The first layer formed with germanium nitride, which is the second layer.
On the other interface of the layer, one of amorphous silicon, amorphous silicon germanium, and amorphous germanium containing silicon nitride or boron and at least a hydrogen atom or a halogen atom is formed. Claims (1) to (4) are characterized in that:
The photoconductor according to any one of paragraphs.