JPH06282088A - Production of photosensitive body - Google Patents

Abstract

PURPOSE:To produce a photosensitive body for forming a high-contrast picture. CONSTITUTION:A cylindrical substrate is arranged in a plasma producing region. A first non-single crystal layer 31 of a P or N-type semiconductor contg. hydrogen, fluorine or chlorine, mixed with boron or indium or phosphorus or antimony and consisting essentially of silicon mixed with nitrogen, carbon or oxygen, a second non-single crystal layer 32 of an intrinsic or practically intrinsic silicon semiconductor formed on the layer 31 and contg. hydrogen, fluorine or chlorine and a third non-single crystal layer 33 of a semiconductor 1 or semiinsulator formed on the layer 32, with the conductivity different from that of the layer 31, consisting essentially of silicon, contg. hydrogen, fluorine or chlorine and further mixed with carbon are formed on the substrate to produce the photosensitive body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic copying machine.

[0002]

2. Description of the Related Art Conventionally, an electrostatic copying machine has used an intrinsic compound semiconductor in a layer for selectively charging static electricity by utilizing a photoelectric effect. However, in this method, the material itself is a pollutant and a carcinogen is printed, and in addition to neutralizing the charge already generated by the charge generated by light irradiation, the contrast is increased (S / N ratio is increased). I wasn't necessarily satisfied with what I did.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic copying machine which satisfies the above-mentioned matters.

[0004]

Therefore, according to the present invention, as a photoconductor for electrophotography, a P-I-N junction or a N-I-P junction is provided in a semiconductor or semi-insulator having a photoelectric effect, and a semiconductor is provided. The internal electric field is formed by the junction inside, and the energy band is W-N-W (WIDE-TO-N).
ALLLOW-TO-WIDE) structure was used to generate a recombination electric field to increase the SN ratio, and non-polluting substance silicon or its compound, particularly silicon carbide or silicon nitride was used.

That is, a first layer of a P or N type semiconductor is provided on a conductive substrate and is formed on the layer without adding an intrinsic or substantially intrinsic (P or N type impurity artificially). The electrostatic copying machine is provided with a second layer of a semiconductor or a semi-insulator, and a third semiconductor or a semi-insulator having a conductivity type opposite to that of the first layer is further provided on the second layer. The present invention provides a semiconductor or semi-insulating material, which is the third layer, or an insulating or semi-insulating film having a thickness capable of flowing an electrostatic charge on the layer, and is selectively photoexcited with the charged electrostatic charge on the film. The electric charges are recombined with each other, and the electrostatic charge or the photo-excited majority carrier is promptly discharged to the conductor on the back surface.

[0006]

Embodiments will be described below with reference to the drawings.
FIG. 1 shows the elements of an electrostatic copying machine to which the present invention is applied. That is, in FIG. 1A, a photoconductive semiconductor (1) is provided on a conductive substrate. Furthermore, static electricity (3) was distributed uniformly on this semiconductor.
In the drawing, positive charges are discharged from the electrostatic charge generation source and are attached to the semiconductor (1). After this, Fig. 1 (C)
As shown in Fig. 2, when the light (5) is locally irradiated, the area (6) (6 ') irradiated according to the amount of light and the wavelength thereof is irradiated.
The static electricity of (6 '') is discharged to the conductor (2). In addition, among the electron-hole pairs generated by photoexcitation, negative electrons in the figure recombine with this positive static electricity and neutralize it. Thus, the static electricity could be selectively distributed on the semiconductor.

FIG. 2 shows the principle of an electrostatic copying machine in which a semiconductor and a layer are provided as a rotating drum, that is, the surface portion of the rotating drum has a multilayer structure of conductors and semiconductors as in FIG. It is provided. Further, the static electricity emitted from the static electricity generation source (8) is evenly distributed as shown in (3) on the upper surface of the drum. Further, reflected light (5) from an object (for example, a printed paper surface) (11) from a light source (7) passes through a slit (9) and illuminates the drum. Then, a photoelectromotive force is generated in the semiconductor in the irradiated surface region, and by the recombination of the negative charge and the emission of the positive charge to the substrate conductor,
Intensity (4) of static electricity (3) is generated according to the irradiation light (5). Further, the surface of this rotary drum is carbon powder or a mixture thereof (1.0 to 100) in the part (12).
Disperse black powder with a particle size of μ on the drum surface. Then, this powder adheres to the drum surface in proportion to the amount of static electricity, so-called "visualization".

Further, the rotation of this drum (speed is 1 to
At the same speed as 10 seconds / revolution), the black powder comes into contact with the surface and the copy object, for example, a new paper (13), moves to adhere the powder onto the copy object. After this this paper (13)
Copying is completed after printing and fixing. The powder remaining on the surface of the drum reaches the first static electricity generation source after being completely removed by the brush (14).

FIG. 3 is an energy band diagram of a conventional non-junction type photoconductive semiconductor (1). In the drawing (A), a semiconductor (1) is provided on a conductor (2). Further, when positive (+) static electricity (3) is added here, the energy band is rounded as shown in FIG. 3 (B). Also, it is excited (14) by light irradiation and electrons (15) are recombined with this static electricity. The holes (16) are also emitted to the conductor (2) on the back surface. As a result, (D) is formed according to the degree of light irradiation, the same surface as (A) where the light irradiation is strong, and (D) does not occur again where the light irradiation is weak ( B) is selectively provided.

The main feature of the present invention is to use not a semiconductor such as CdS but a non-single-crystal silicon semiconductor or a semiconductor or semi-insulator to which silicon and carbon, nitrogen or oxygen are added. The semiconductor or semi-insulator is not itself a pollutant, and the addition of C and N increases the insulating property, and as a result, the required thickness of the semiconductor layer is reduced to 1/3 to 1/10 of the conventional thickness. It has the characteristic that it can be thinned and has excellent wear resistance as a drum.

Fabrication of such a semiconductor or semi-insulating layer was performed as follows. SiH ₄ , SiH ₂ Cl ₂ , SiC
l ₄ and SiF ₄ are introduced from (40). Further, when forming a P-type semiconductor, B ₂ H ₆ , I, which is a trivalent impurity, is formed.
nCl ₃ is simultaneously diluted and introduced with helium or the like. Furthermore, the drum (42) has a diameter of 20 to 40 cm,
Having a length of 250-500 cm, this drum (42) was rotated at a speed of 0.1-1 times / sec. The surface of this drum is made of aluminum or its compound, and the surface to be coated with Ar is mixed with Ar or a mixed gas of Ar and H by plasma sputtering in vacuum before coating the aluminum oxide on the surface with a silicide gas. To remove oxides or dirt. Further, a silicide gas such as SiH, SinH _{2n + 2} , (n ≧ 2), S
Nozzle (48) in the center of the electrode (47) such as iF ₄
Introducing plasma, plasma is applied at a frequency of 0.01 to 50 MHz or a frequency of 1 to 10 GHz, and a power of 100 W to 1 KW is applied to generate plasma between the drum (42) and the electrode (47) as shown in FIG. 4 (B). Squeezing reactive gas is the nozzle (4
8) heating this drum to 200-500 ° C. so that all the emitted from it reacts and deposits its product on the drum, and DC plasma CVD between this drum and the electrode (47). What is done is another feature of the present invention.

As a result, there is little deposition of silicide on the inner wall of the reactor (50), and hydrogen or hydrogen and a halogen element such as fluorine are added to silicon using a simple parallel plate type glow discharge method or arc discharge method. Material yield of 15 to 90% compared to the method using amorphous silicon added with
The cost can be improved to 5%, and the material can be effectively used, and the cost can be reduced.

The reaction furnace is filled with a silicide gas, especially silane, in an amount of 3 to 3
0% He = 95 to 70%, and B ₂ H ₆ or InCl ₃ is added to 0.1 to 5 to form a P-type or P ⁺ -type layer.
%Introduce. To make an N-type layer, PH _3, SbCl ₅
Were mixed simultaneously at the same time. In that case, the amount of helium that is the diluent corresponding to that amount was reduced. Helium was the lightest of all gases and had a thermal conductivity about three times higher than that of Ar and the like, and was a very preferable diluent gas for uniform heating in the reaction furnace, that is, for uniform film thickness.

Further, He has an ionization voltage of 21 eV at the time of ionization, which is extremely large as compared with 12 to 15 eV of other gases, and as a result, the contribution to the continuation of the plasma state was large. Further, methane or ammonia was added at the same time in order to make the formed film not a semiconductor but a semi-insulator. Then Si ₃ N _4-x (0 <x <
4) is formed and when 1 to 30 mol% of nitrogen is added, the coating has an Eg of 2.0 to 3.0 eV and 1.0 to 10% of silicon.
It could be made larger than 1.8 eV. In addition, the abrasion resistance is also improved. The electrostatic copying machine of the present invention is not simple silicon, but 1 to 50 mol% of carbon or nitrogen is added, and in particular, the surface of the semiconductor where electrostatic is adsorbed or the vicinity thereof is carbon. Or by increasing the amount of nitrogen added, SiC _1-x , Si ₃ N
_{In 4-x} , x was made small to have a wide energy band width and to improve wear resistance.

By doing so, the gradual decrease due to the leakage of static electricity was small, and the static electricity could be held on the semiconductor or the semi-insulator for a long time. Tetramethylsilane (Si) which is MO (metal organic compound) is used to introduce the carbide gas.
(CH ₃ ) ₄ ) (BP 26.4 ° C.) and tetraethylsilane (Si (C ₂ H ₅ ) ₄ ) (BP 153 ° C.) may be used. When such a carbon or silicon compound is used, there is no concern that silicon or carbon clusters will be present in the formed semiconductor or semi-insulator, and the semiconductor characteristics will not be impaired, which is extremely preferable.

FIG. 5 shows the principle of operation of an electrostatic copying machine according to the energy band diagram of the semiconductor of the present invention. In the drawing, a semiconductor (1) is in contact with a conductor (2) and is composed of a first layer (31) of a P-type semiconductor or a semi-insulator, an intrinsic or substantially intrinsic second layer (32) and an N-type third layer. The layer (33) is provided, and the transition regions (37) and (36) between the layers are formed. Furthermore, the conduction band (38) and the valence band (39) of these first, second and third layers are continuous and do not have discontinuities such as kinks and dips in terms of energy band.

The energy band width may be the same for each layer, but here, a wide energy band width is formed in order to form an internal electric field for promoting drift of electrons to the front surface of electrons / holes during light irradiation and drift of electrons to the back surface of holes. The first layer (31) of (WIDE) -the (NALLOW) second layer (32) of small energy bandwidth-the third layer (33) of wide energy bandwidth is P (31) -I (3).
2) -N (33) junction is provided.

Due to such an internal electric field, the diffusion of the holes into the back surface conductor (1) is 10 ² to 10 as compared with the conventional case.
^{This is four} times faster, and as a result, this semiconductor (2) can be made to have a thickness of 100 to 10 μ ± 20 μ, which is 1/2 to 1/3 that of the conventional one, which is preferable in terms of resource saving. In addition, since the thickness was thin, the occurrence of cracks and the like due to thermal stress with the back conductor was reduced, which was more preferable. In addition, the conductor on the back side is made of aluminum to reduce the weight and the semiconductor of this drum is manufactured by the plasma CVD method from 300 to 300.
It was possible to carry out the production at a temperature of 650 ° C. simultaneously with the production of the sinter for ohmic contact.

Further, as shown in FIG. 1B, positive static electricity (3) is applied to the surface of the semiconductor (1) in FIG. 5A.
Is charged, the surface band goes down as shown in FIG. 5 (B). When the light irradiation is selectively performed as shown in FIG. 1C, the photoexcited electrons (15) drift and recombine with the static electricity (3) on the surface. Also, the holes (16) are formed on the back surface by the junction electric field of the PIN junction and the WIDE-TO-NA.
An internal electric field due to the LLOW-TO-WIDE structure causes rapid discharge to the conductor (2). Then, according to the electric field, static electricity (3) remains as shown in FIG. 5 (D), a region without light irradiation is selectively shown in FIG. 5 (B), and a region with strong light irradiation is selectively shown in FIG. 5 (A). Can be formed.

According to the present invention, in this PIN structure, the material is SiC _1-x (0 <x <1) (when x = 1, only silicon is formed) by adding carbon or nitrogen thereto rather than silicon itself. , Si ₃ N _4-x (0 <x <4) (where x
= 4 only silicon) and a semiconductor or semi-insulator having high resistance, and the first and second layers have carbon of 10 to 50 mol% and nitrogen of 5 to 5 mol%.
30 mol% is added and the second layer has 1-2 carbon in carbon.
Addition of 0 mol% and 0.1 to 5 mol% of nitrogen increases the S / N ratio at the time of light irradiation, and reduces the thickness of the second layer to 1/5 to 1/20 by 1 to 50 μm. However, the static electricity could be retained for 10-50 seconds to 1-5 minutes. Furthermore, the third layer is made of silicon carbide (S
iC _1-x (0 ≦ x <1)) or silicon nitride (Si ₃ N _4-x
Another feature is that the use of (0 <x <4) does not cause deterioration in the electrostatic holding property even when electrostatic copying is performed 10 ⁴ to 10 ⁶ times.

FIG. 6 shows another embodiment of the present invention. In the drawing, (A) is an NI for a semiconductor or a semi-insulator (1)
P structure and W (31) -N (32) -W (3
3), the third layer (33) is N or N ⁻ , and the first layer is P ⁺ . Similar to FIG. 6B, the third layer (33) is N ⁺ .

FIG. 6 (C) shows a thickness of 10 to 1000 Å at which an insulator made of silicon carbide (SiC) or silicon nitride (Si ₃ N ₄ ) can flow current on the upper surface of the third layer (33).
It has a thickness of 10 mm to improve static electricity retention characteristics. That is, FIG. 6C is composed of a semiconductor layer (32) and a semi-insulator (33) on the upper surface thereof, and further, silicon nitride (Si ₃ N ₄ ) having a thickness capable of passing a current of 30 to 10 is formed on the upper surface.
It is formed with a thickness of 0Å. This silicon nitride has an energy band width of 5.0 eV, is harder and has better wear resistance than silicon oxide, and has a thickness of 30 to 1
Even if it is as thick as 00Å, current can flow. Therefore, it has two characteristics as compared with the protective film of silicon oxide. In the present invention, the introduction of silane is stopped and only ammonia is introduced into the reaction furnace of FIG. The surface may be carbonized or nitrided.

[0023]

As is apparent from the above description, the present invention uses a semiconductor containing silicon as a main component, which is less expensive than an electrostatic copying machine using a conventional compound semiconductor such as CdS. Nitrogen was added to the surface of the semiconductor, especially at or near its surface, to increase the hardness and wear resistance, and to prevent static electricity leakage by semi-insulating the semiconductor. It is possible to improve the S / N ratio by providing a P type semiconductor near the conductor substrate or the drum and forming an IP junction to generate an internal electric field.

In the embodiments of the present invention, the case where positive static electricity is applied was mainly described. However, if negative electrostatic charge is applied, the junction should be P (third layer) -I (second layer).
It is sufficient to determine the conductivity type of the first semiconductor layer on the conductor to be -N (first layer), and the relationship is completely opposite.

Furthermore, since the semiconductor or semi-insulating material on the drum is coated by the low pressure CVD method using DC plasma while rotating the drum, the loss due to the adhesion of the material to the wall of the reaction furnace is reduced. I believe that it is extremely important from an engineering point of view.

[Brief description of drawings]

FIG. 1 shows the principle of local charging of static electricity according to the present invention.

FIG. 2 shows the principle of a drum type electrostatic copying machine to which the present invention is applied.

FIG. 3 shows an energy band diagram of a conventional semiconductor.

FIG. 4 shows the principle of a manufacturing apparatus for making a copying machine of the present invention.

FIG. 5 shows an energy band diagram of a semiconductor of the present invention.

FIG. 6 shows an energy band diagram with another semiconductor or semi-insulator structure of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 semiconductor 2 conductor 31 1st layer 32 2nd layer 33 3rd layer 36, 37 transition region 38 conduction band 39 valence band

Claims (1)

[Claims] 1. A conductive substrate is made of cylindrical aluminum or a compound thereof so as to serve as one electrode for generating plasma in a reaction furnace, and the electrode is arranged opposite to the surface of the conductive substrate. , Generating a plasma between the conductive base and the electrode, and rotating the cylindrical conductive base in the plasma generation region, and at the surface of the cylindrical conductive base, carbide gas, oxide gas or nitride The main component is silicon which contains hydrogen, fluorine, or chlorine, and is added with nitrogen, carbon, or oxygen by reacting an additive gas consisting of a gas, a silicide gas, and a P or N type impurity gas. Forming a first non-single-crystal layer of a P-type or N-type semiconductor or semi-insulator on a conductive substrate, and introducing the additive gas onto the first non-single-crystal layer. Without reacting the silicide gas Forming a second non-single-crystal layer of an intrinsic or substantially intrinsic silicon semiconductor containing hydrogen, fluorine, or chlorine, and reacting a carbide gas and a silicide gas on the non-single-crystal layer. And a step of forming a third non-single-crystal layer of a semiconductor or semi-insulator containing silicon as a main component to which carbon is added at least and hydrogen, fluorine or chlorine is added. How to make