JPS6298361A - Photoconductive body - Google Patents

Abstract

PURPOSE:To reduce a dark current and an operating voltage of the photoconductive body by sticking the 1st layer composed of a film contg. a noncrystalline silicon, etc., as a main component to the 2nd layer composed of a film comprising a germanium carbide contg. an atom belonging to the group IIIb atoms of the periodic table as the main component. CONSTITUTION:The 1st layer comprises the film composed of the non-crystalline silicon contg. a hydrogen atom or a halogen atom, the film composed of the non-crystalline silicon and germanium, or the film composed of the non- crystalline germanium as the main component respectively. The 2nd layer comprises the film composed of the germanium carbide contg. the atom belonging to the group IIIb atoms of the periodic table, such as the boron or the aluminum atom as the main component. The titled body is obtd. by sticking the 1st layer and the 2nd layer at an interface thereof. Thus, as the atom belonging to the group IIIb atoms of the periodic table is incorporated, the titled body having the low dark current and the low operating voltage is obtd. The titled body may be used for a electrophotographic sensitive body or a image pickup device.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention comprises an amorphous material mainly composed of silicon atoms and/or germanium atoms and germanium carbide containing atoms of Group 1II b of the periodic table. The present invention relates to a photoconductor.

(Prior art) Amorphous silicon hydride and amorphous silicon germanium hydride have been used in imaging devices and electrophotographic photoreceptors because they have excellent photoconductivity and heat resistance, and are non-polluting. Development research is active.

FIG. 5 is a sectional view of a conventional photoconductor.

In the same figure, alumina (hereinafter abbreviated as AN20.) or silicon oxide (hereinafter referred to as 5j
Oxide (hereinafter abbreviated as 5iNX) was formed thereon, silicon nitride (hereinafter abbreviated as 5iNX) was formed as an organic polymer layer 33 such as polycarbonate, and a transparent electrode 34 was further formed thereon by a sputtering method. It is something. (References: JP-A No. 56-24356, JP-A No. 57-58161) (Problems to be solved by the invention) The electron blocking layer is replaced with the conventional 5inx, A[, O,
.

When composed of SiNx or organic polymers, it forms a barrier against holes in the photoconductive layer, causing problems in reducing operating voltage (reducing afterimages and residual potential in imaging devices and electrophotographic photoreceptors). was occurring.

The purpose of the present invention is to eliminate the conventional drawbacks and to
An object of the present invention is to provide a photoconductor that uses a film mainly composed of germanium carbide (hereinafter abbreviated as GeCx) containing group atoms as an electron blocking layer and enables low dark current and low operating voltage.

(Means for Solving the Problems) The photoconductor of the present invention comprises a film mainly composed of amorphous silicon containing at least hydrogen atoms or halogen atoms, a film mainly composed of amorphous silicon germanium, and a film mainly composed of amorphous silicon germanium. A first layer consisting of any one of films mainly composed of amorphous germanium or a combination thereof, and atoms of the tub group in the periodic table on at least one interface of the first layer. A second material whose main component is germanium carbide containing
It forms a layer of

Further, the first layer contains any one of oxygen atoms, nitrogen atoms, and carbon atoms, or a combination thereof. Furthermore, the first layer contains at least one of boron atoms and phosphorus atoms.

Further, the second layer, which is germanium carbide containing group IIIb atoms in the periodicity table, contains either one or both of oxygen atoms and nitrogen atoms. Further, on the other interface of the first layer, which is a second layer made of germanium carbide containing periodicity column 1IIb Hirohara'F-, germanium carbide, silicon carbide, germanium nitride, silicon nitride, or oxide is added. It forms silicon. Further, the second layer, which is a periodicity column + the other interface of the first layer formed of germanium carbide containing Nb group atoms, contains a phosphorus atom and at least a hydrogen atom or a halogen atom. It forms any one of amorphous silicon, amorphous silicon germanium, and amorphous germanium contained therein.

(Function) GeCX exhibits n-type conduction, but when it contains atoms of group 1IIb in the periodic table cylinder, it exhibits p-type conduction. therefore.

Gecx, which contains periodicity column + n B group atoms, prevents electrons from being injected from the outside into the amorphous silicon that is the photoconductive layer, and also prevents holes in the amorphous silicon from being injected from the outside. Since no barrier is formed, dark current is reduced and operating voltage is lowered. Furthermore, even when the photoconductive layer is made of amorphous τ silicon germanium or amorphous germanium, which has a narrow forbidden band width, the forbidden band width of GcCx can be increased by decreasing the carbon composition ratio X of GeCX. Since it is easy to reduce, GeCx containing rb group atoms in the periodicity table cylinder.

Even for a photoconductive layer having a narrow forbidden +h band width, it can effectively act as an electron blocking layer, and it is possible to obtain 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 4.

To create GeCx used in the present invention, Ge1-14
゜Ge, It, l Ge, l, , GeF4. G
e1IF, , GeHCl3. GeH,F.

GeC1,, GeHCl3. GeH, C1,, GaH
, (J, GeF2. Ge (J2 and other Ge atom source gases and Ctl4. C2H,, c, ++, ).

C,lI, , C,lI, , C,11c, C
,lI, , C,II□, C,Il, , C4H
Plasma CVD method using raw material gas of C atoms such as G.

Target is Ge or GeC, Ar, H2,C
11,.

A reactive sputtering method in C, H4, Cdi□ is used. Periodic table clause mb1 to be included in GeCx!
A atoms are boron (B), aluminum (H), gallium (
Ga) and indium (In) are preferred, especially B and AI! is optimal. In order to contain these atoms in GeCX, B, Il, , OF, , BC et al.+
B8r, , (Ctl,)3AN.

(C2115)ffAI! t (i-C, H9)31.
1clff, (Ctl,), Ga.

(Czlls)aGa+ (C)13), In, (C
In the plasma CVD method, a gas such as zHs)3In is mixed with the above-mentioned source gas for GeyK atoms or source gas for C atoms. In the reactive sputtering method, the above-mentioned Ar, It□.

CH4, C21+4. It may be mixed into C21t□. In addition, amorphous silicon of the photoconductive layer (hereinafter, depending on the type of atoms contained in the film, a-3i: H, a-5i
:tl:X, a-5i:X (abbreviated as X=halogen atom)) is 5il14°5i211. ,
Si, Il, , 5iF4r 5iHF, , S
iH□C&, Sj'H,F.

5jCI4.5jt(C#, , SiH□C&, ,
Plasma CVD method using raw material gas of Si atoms such as SiH, C4l, or gas diluted with Ar, lle, 11□, etc., or using Si as a target in a mixed gas of Ar and 112, or with Ar. SiF4
It can be formed by reactive sputtering or vapor deposition in a mixed gas. Amorphous germanium (hereinafter referred to as a-Ge:tl, a-Ge:lI depending on the type of atoms contained in the film)
: X, a-Ge: Or A targeting Ge
In a mixed gas of r and 142 or Ar and GeX4 or G
e114-oXn (however, X=F or Cj, n=1.
Amorphous silicon germanium (hereinafter referred to as a-5i, -zGez depending on the type of atoms contained in the film)
:It, a-5L, -XGeX:H:X or a-3
it-xGex:X (abbreviated as X (X =: halogen atom)) is also a mixed gas of the above-mentioned Ge atom raw material gas and Si atom raw material gas, or this mixed gas is mixed with Ar,
Plasma CVD method using a gas diluted with a gas such as Ile, Il2, or a mixed gas of Ar and 11□ using a mixed target of SL and Ga or two targets of SL and Ge, or a mixed gas of Ar and SiX4
or 5il14-, , Xn (however, X = halogen atom, n = 1.2.3) and, or GeX4 or Ge
H4-fiXn (However, X=F or CL n=1.
It is formed by the reactive sputtering method or vapor deposition method in a mixed gas of 2.3).

Examples 1 to 3 will be described using the plasma CVD method, and Example 4 will be described using the reactive sputtering method.

Example 1 In FIG. 1, a mirror-polished ρ substrate 1 is placed in a capacitively coupled plasma CVD apparatus, and the interior of the reaction vessel is
After evacuation to 10-' Torr or less, the Aρ substrate 1 is heated to 150 to 250°C. GeF: 1
to 5sec, C2It4: 5 to 1010
5e, 1% B, Il, diluted with He: 0
．． After introducing 5 to 20 sec into the apparatus and adjusting the pressure in the reaction vessel to 0.2 to 1.0 Torr, the boron-doped GeCx layer 2 was applied onto the AN substrate 1 using a high frequency power of 50 to 200 W at 13.56 M°. 0.2μm
Formed and then 5il14: 101005e, 40pp++ 4 degrees 8211 diluted with hydrogen: 2 to 4
sec+n is introduced, and the pressure is 0.2 to 1.0 Tor.
r, boron-doped i with high frequency power +50 to 400W
Type a-5i: It layer 3 is formed to have a thickness of 8 μm. Furthermore, an ITO transparent electrode 4 is formed by a sputtering method.

Dark current and wavelength of 435 nm when voltage is applied so that the AI substrate 1 is negative and the upper ITO transparent electrode 4 is positive
Figure 2 shows the voltage dependence of the photocurrent for light. As shown in FIG. 5 as a conventional example for comparison, instead of the boron-doped GeCX layer 2 in FIG.
Figure 2 shows the voltage-current characteristics of a structure using SiN layer 3z, 0°2 μm as a blocking layer, fabricated with 50 to 101005c, gas pressure of 0.2 to 1.0 Torr, and discharge power of 100 to 400 W. . As is clear from the figure, the embodiment of the present invention has a low operating voltage.
Moreover, it has a low dark current.

5jNx layer (blocking layer) 32 is made of boron-doped Ge.
Like the Cx layer 2, it works as an electron blocking layer, but it forms a barrier for holes in the boron-doped i-type a-3i:8 layer 3, and the boron-doped layer does not form a barrier. The operating voltage is higher than that of GeCx layer 2.

In addition, the photoconductor shown in Figure 1 was replaced with an electrophotographic photoreceptor (I
When used with positive charging (with the TO electrode 4 and external circuit removed), the saturated surface potential was 500 V and the residual potential was 5 ■ or less. Embodiments of the present invention provide an electrophotographic photoreceptor with high charge acceptance and low residual potential. Also, instead of boron-doped a-5i:II layer 3, a-5
i1-xGeX: l! , a-5j, xGex: It
: X, a-3i, -xGex: X (X = halogen atom) or a-Ge: 11, a-Ge: If
: X, a-Ge :
Ge:If and a-si:II, a-5L, xGe,
: It and a-3i: It or a-Ge: II and a-
5j1-xGex: An example is a combination of stacking It.

Furthermore, even if a similar combination is used when containing a halogen atom
has the same effect as above.

Example 2 In FIG. 3, a mirror-polished l' dome 10 is placed in a capacitively coupled plasma CVD apparatus, and the interior of the reaction vessel is
After evacuation to below X 10-' Torr, the AN dome 10 is heated to 150 to 250°C. Ge
114: 10 to 50 sec, C114: 1.
0 to 50 sec, 1% 1° diluted with He
321+: 50 to 101005e introduced, pressure crab 0.2 to 1, 0 Torr, high frequency power 10
The boron-doped GeCx layer 11 was heated at 0 to 500 W.
．． 2 to 1.0 μm, and then GeF-: 2 to 10105e, 5i11. : 100 to 20
0sec, 40ppm concentration of 8211G diluted with hydrogen
: Introduce 2 to 45 ccn, pressure 0.2 to 1
, 0 Torr J high frequency power +50 to 400 W, boron-doped a-5i1-XGex: II: F layer 12 is formed to a thickness of 2 to 4 μm, and then 5ill:
100 to 200sec, 20pp diluted with hydrogen
A-Si:8 layer 13 doped with phosphorus is formed to a thickness of 10 to 15 μm under the following manufacturing conditions: 0.5 to 2 seconds, pressure of 0.2 to 1.0 Tor, and high frequency power of 150 to 400 W.

Further 5il14: 50 to 101005e, C
114: 20 to 80 SCCm, pressure 0.2 to 1, 0 Torr, high frequency power 150 to 100
The silicon carbide (hereinafter abbreviated as 5jCx) layer 14 is coated with W to 10
00 to 2000 people are formed to obtain an electrophotographic photoreceptor.

The spectral sensitivity of this electrophotographic photoreceptor when positively charged is 400.
High sensitivity over a wide range from 800 nm to 800 nm, boron-doped a-5jx-XGex: II: F layer 1
a- with phosphorus added to 2 as a photoconductive layer for long wavelength light
5i: II′! By adding to jjj13,
We were able to confirm an improvement in photosensitivity in the near-infrared region. This electrophotographic photoreceptor was mounted on a laser beam printer using a semiconductor laser with a wavelength of 800 nIll as a light source, and clear printing was confirmed. In this case, the boron-doped GeCx layer 11 has a narrow bandgap by reducing the carbon composition ratio X, and has the role of not only an electron blocking layer but also a laser beam absorbing layer. This prevents the resolution from deteriorating due to reflection of the laser beam on the 10 surface. Furthermore, in order to stabilize the electrophotographic photoreceptor and increase its resistance, boron-added a-5i□-XGe:11:F)WJ
Carbon atoms, oxygen atoms, or nitrogen atoms may be added to the +2 and/or phosphorus-doped a-5i:11 layer 13, and oxygen may be added to improve the adhesion between the boron-doped GeC layer 11 and the AI dome 10. A layer 11 of GeC doped with boron atoms or nitrogen atoms may be added. In this case, the 5iCx layer 14 was used as the 5th layer of the surface layer, but the 5iCx layer 14 was used as the 5th layer of the surface layer.
Instead of iCx, 5jnx, SiN, GeN, or GeCx may be used. In addition, instead of the boron-doped a-3i1-xGeX:II:F layer 12 and the phosphorous-doped a-si:11 layer 13 of the photoconductive layer, boron-doped a-Ge:II and phosphorus-doped a511-xGe are used. ,
: Lamination of It or boron-doped a-Ge:I
The use of a stack of I and phosphorus-doped a-5i:II also works effectively as a blocking layer of 11 boron-doped GcCX layers.

Example 3 As in Example 2, 5il14:
100 to 200 sec, hydrogen diluted 1010
0pp degree PF3: 100 to 200sec+n, gas pressure 0.2 to 1, 0Torr, high frequency power】00
-N-type a-5i with phosphorus added at 400W: II
: F film 0.2 to 1. 5i11. : 100'9 to 200sec
, a gas pressure of 0.2, c) LL, 0 Torr, and high frequency power of 100 to 400 W to form an a-5i:tl film with a thickness of 10 to 20 μm. Furthermore, Ge11. : 2 none)
10s105e cl+4: 40 to 100se
c+e, 10 layer concentration BF diluted with Ile, ? 0
．． 5 to 20 seconds, gas pressure 0.2 to 1,
1000 to 5000 boron-doped GeCx layers were formed at 0 Torr and high frequency power of 100 to 400 W to produce an electrophotographic photoreceptor. When this electrophotographic photoreceptor was installed in a commercially available copying machine, it was confirmed that it could withstand rigidity of 800,000 sheets or more and produce good images even when negatively charged.

Example 4 In FIG. 4, a glass substrate 21 with an ITO transparent electrode 20 formed on its surface was placed in a magnetron sputtering device, and Ge polycrystalline was used as a target at a substrate temperature of 250°C.
r: 1 to 3 mTorr, CI+4: 2 to 6 mTorr, 13.56 MIIz high frequency power 30
1000 to 3 GeCx layer 22 at 0 to 500W
Form 000 people. Next, Sj polycrystalline meta-get, Ar:L to l OmTorr, 2 diluted with hydrogen
[32H, with a concentration of 0ρρm: 0.3 to 0.4 mT
orr, a boron-doped asi:II layer 23 is formed to a thickness of 2 to 3 μm using a high frequency power of 300 to 800 W. Next, a 10-layer concentration of 8211.Ge polycrystalline was targeted and diluted with Ar. : 1 to 3 mTorr, CI
L: 2 to OmTorr, 1000 to 3000 boron-doped GeCX layers 24 are formed at high frequency power of 300 to 500W. Furthermore, electron beam landing 5b2s and layer 25 are deposited by 1000 people to produce an image pickup tube target. Since the ITO transparent electrode 20 is positively biased with respect to the cathode 26, electron and hole pairs generated by incident light from the glass substrate 21 side are separated by the electric field in the film.

Holes are lifted to the upper surface in the boron-doped a-5i:1123 layer, and electrons are transferred to the lower ITO transparent electrode 20.
gather at The boron-doped GeC layer 24 allows holes to travel easily and acts as a blocking layer for 'Iπ electrons.
The layer 224 allows electrons to travel easily and acts as a hole blocking layer. In addition, the addition of boron makes it easier for the holes in the a-5i:8 layer 23 to move, and the embodiment of the present invention shown in FIG. It was done.

Also, instead of the GeCx layer 22, 5xNz, aeN
Using x+5IOx+5jCX yields similar results as above.

(Effects of the Invention) The light guide 17 according to the present invention has a low dark current and a low operating voltage, and can be used as an electrophotographic photoreceptor or an imaging device. In particular, when used as a photoconductor for laser beam printers, by reducing the forbidden band width of boron-doped GeCx, it not only blocks electron injection but also effectively absorbs laser light, making it effective for practical use. This is the element configuration. Furthermore, GeCX has a high surface hardness, and by increasing X, it becomes transparent to visible light, so it is suitable for the surface protective layer of a photoreceptor, and has various practical effects.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a photoconductor in an embodiment of the present invention;
FIG. 2 is a diagram showing the voltage dependence of dark current and photocurrent, FIG. 3 is a cross-sectional view of an example of application of the photoconductor of the present invention to an electrophotographic photoreceptor, and FIG. 4 is a diagram showing the photoconductor of the present invention. FIG. 5 is a cross-sectional view of a conventional photoconductor. 1-A & substrate, 2.11, 22.24- GeC, layer, 3- i type a-5i:II layer, 4.20
・11'O transparent electrode, 10...AQ toum, 12
・ a-si, -xGeX: II: F layer, 13
．． 23-a-3j: 11 layers, 14-5iCx layer, 2
1... Glass substrate, 25... sb, s, layer, 26
・Cathode. Patent applicant: Matsushita Electric Industrial Co., Ltd. - 1) Agent: Tsune Tsune Hoshino - 1 □ Part: 1゛1-2 Figure 1 1°・Δl/Twin Handling 2 ゛11i Localized GeC8 Layer 3...
stone) ill end? Omi Karoshi Dingζ a-S=:+Tongue 4゛ITO Transparent Zogi α Figure 2

Claims (6)

[Claims] (1) Which of a film mainly composed of amorphous silicon containing at least hydrogen atoms or halogen atoms, a film mainly composed of amorphous silicon germanium, and a film mainly composed of amorphous germanium a first layer consisting of one or a combination thereof, and a second layer mainly composed of germanium carbide containing atoms of group IIIb of the periodic table on at least one interface of the first layer. A photoconductor characterized by forming. (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 photoconductor according to claim (1) or (2), wherein the first layer contains at least one of boron atoms and phosphorus atoms. (4) Claim (1) characterized in that the second layer, germanium carbide containing atoms of group IIIb of the periodic table, contains one or both of oxygen atoms and nitrogen atoms. The photoconductor according to any one of Items to Items (3). (5) Germanium carbide or silicon carbide is formed on the other interface of the first layer on which germanium carbide containing atoms of group IIIb of the periodic table is formed, which is the second layer.
Alternatively, the photoconductor according to any one of claims (1) to (4) is formed of germanium nitride, silicon nitride, or silicon oxide. (6) On the other interface of the first layer, which is made of germanium carbide containing atoms of Group IIIb of the periodic table, which is the second layer, contains phosphorus atoms and at least hydrogen atoms;
or any one of amorphous silicon, amorphous silicon germanium, and amorphous germanium containing halogen atoms is formed. The photoconductor according to any one of paragraphs.