JPH0310304B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrophotographic photoreceptor, particularly to the structure of an electrophotographic photoreceptor having sensitivity from visible light to near-infrared light.

Structure of conventional example and its problems The spectral sensitivity of conventional electrophotographic photoreceptors is not high in the entire visible light range, except for photoreceptors using amorphous hydrogenated silicon. Incidentally, recently, there has been active development of photoreceptors for laser printers that are characterized by high speed and high resolution. In order to miniaturize this laser printer, it is necessary to develop an electrophotographic photoreceptor that has high sensitivity in the near-infrared light region of around 800 nm, which is the oscillation wavelength of the semiconductor laser used as the light source. However, even electrophotographic photoreceptors that are highly sensitive to visible light have a considerable decrease in sensitivity in this near-infrared light region. For this reason, long-wavelength sensitivity has been improved by introducing Te into Se-based photoreceptors and Ge into amorphous hydrogenated silicon, but increasing the sensitivity to infrared light reduces the charging potential. At present, photoreceptors with sufficient characteristics have not been obtained.

Purpose of the Invention The purpose of the present invention is to provide a photoconductor that is highly sensitive in the visible light to near-infrared region, and is particularly sensitive in the near-infrared region, making it suitable for use in laser printers using semiconductor lasers. An object of the present invention is to provide a photographic photoreceptor.

Structure of the Invention According to the present invention, a functionally separated electrophotographic photoreceptor is constructed which includes a charge generation layer and a charge transport layer formed on a conductive support, and the charge generation layer (Cd _x Zn _1-x Te) _1-y (In ₂ Te ₃ ) _y (O≦x≦1, O≦
y≦0), and the charge transport layer is composed of a layer having an electron affinity greater than or equal to that of the charge generation layer.

This charge generation layer, (Cd _x Zn _1-x Te) _1-y (In ₂ Te ₃ ) _y
is a photoconductor that has sensitivity from the visible light region to the infrared light region.

DESCRIPTION OF EMBODIMENTS The basic structure of the present invention is a charge generation layer (Cd _x
A Zn _1-x Te) _1-y (In ₂ Te ₃ ) _y layer 2 was formed, followed by a charge transport layer 3. FIG. 2 shows a band diagram for the configuration of FIG. 1. FIG. 2a shows the state in equilibrium, and FIG. 2b shows the state in positive charging. The light is (Cd _x
Zn _1-x Te) _1-y (In ₂ Te ₃ ) is absorbed in _{the y} layer 2, and electron-hole pairs are generated. The holes travel to the support 1 and the electrons travel through the charge transport layer 3, and the In this way, the charge generation layer (Cd _{x
( Cd x Zn 1 - x}
Te) _1-y (In ₂ Te ₃ ) _y The material of the charge transport layer 3 needs to have the same or larger electron affinity than y.

Although no charge injection blocking layer is provided in FIG _. 1, in order to further increase the charging potential of the electrophotographic photoreceptor, as shown in _FIG. ) _1-y (In ₂ Te ₃ ) When an electron injection blocking layer 4 is provided between the _y layer 2 and the support 1 and a hole injection blocking layer 5 is provided on the surface of the charge transport layer 3, the initial charging potential and dark There is an improvement in damping characteristics.

FIGS. 1 and 3 show examples of positively charged electrophotographic photoreceptors. The charge generation layer (Cd _x
Zn _1-x Te) _1-y (In ₂ Te ₃ ) _y has a structure in which the charge transport layer is reversed, that is, as shown in FIG. 4, a charge transport layer 7 is provided on a conductive support 6, Then (Cd _x Zn _1-x
Te) _1-y (In ₂ Te ₃ ) _y layer 8 is formed.
An electrophotographic photoreceptor with negative charging characteristics is obtained. In this case as well, the charge generation layer (Cd _x Zn _1-x
Te) _1-y (In ₂ Te ₃ ) Hole injection blocking layer 1 on the surface of _{the y} layer 8
0, and when an electron injection blocking layer 9 is provided between the charge transport layer 7 and the support 6, negative charging is achieved with improved initial charging potential and dark decay characteristics compared to the electrophotographic photoreceptor having the structure shown in FIG. An electrophotographic photoreceptor is obtained.

In addition, (Cd _x Zn _1-x Te) _1-y (In ₂ Te ₃ ) _y
When it is >0.1, the dark resistance becomes small and good photoconductive properties are no longer exhibited.

Specific examples are shown below.

Example 1 An electrophotographic photoreceptor as shown in FIG. 6 was prepared. First, on a glass substrate 11 that has been optically polished.
The In ₂ O ₃ layer 12 was formed to a thickness of 1000 Å by vapor deposition at a substrate temperature of 250° C. in an oxygen atmosphere. This substrate was placed in a vacuum evaporation apparatus. Set the board temperature to 200
℃ to form a ZnTe layer 13 with a thickness of 2 μm,
Next, add Cd _0.3 Zn _0.7 Te) _0.95 (In ₂ Te ₃ ) _0.05 layer 14.
The charge generation layer 16 was formed to a thickness of 3 μm and heat-treated in vacuum at 550° C. for 15 to 60 minutes. According to the Kelvin method, the electron affinity of the surface of this charge generation layer is approximately
It was 3.8eV. The substrate having this charge generation layer 16 was placed in a magnetron sputtering device, and
After exhausting to below 10 ^-6 Torr, Ar partial pressure was 7.3mTorr,
A 5 μm thick amorphous hydrogenated silicon layer 15 was formed using a 99.999% purity Si polycrystal as a target under a H ₂ partial pressure of 0.7 mTorr and using a discharge power of 300 W. At this time, a thin Au film of 200 Å was formed by vacuum evaporation on the amorphous hydrogenated silicon formed at the same time, and from the height of the barrier, the electron affinity of this amorphous silicon hydride was
It was determined to be 4.0-4.3eV. The ZnTe-(Cd _0.3 Zn _0.7 Te) _0.95 (In ₂ Te ₃ ) _0.05 layer thus formed was used as the charge generation layer 16, and thereby the amorphous hydrogenated silicon 15 with high electron affinity was used as the charge transport layer. An electrophotographic photoreceptor was used after being positively charged with a corona charger. The spectral sensitivity of this electrophotographic photoreceptor is shown in FIG. 9. For comparison, the spectral sensitivity of amorphous hydrogenated silicon is also shown. As is clear from FIG. 9, according to the present invention, an electrophotographic photoreceptor having high sensitivity from visible light to infrared light can be obtained.

Example 2 As shown in FIG. 7, Si single crystal Weber 21
A SiNx layer 23 was formed to a thickness of 600 Å on a substrate on which a Mo layer 22 was formed to a thickness of 800 Å by electron beam evaporation. Subsequently, a (Cd _0.3 Zn _0.7 Te) _0.95 (In ₂ Te ₃ ) _0.05 layer 24 and an amorphous hydrogenated silicon layer 25 were formed under the same conditions as layers 14 and 15 of Example 1.

Further, on the amorphous silicon hydride layer 25, a second amorphous silicon hydride 26 having a higher hydrogen content than that layer was formed to a thickness of 0.2 μm. The SiNx layer 23 is Si
as a target, Ar partial pressure 2mTorr, _N2 pressure 4
It was formed with a discharge power of 500 W at mTorr and a substrate temperature of 250°C. Second amorphous hydrogenated silicon layer 24
was formed under the same conditions as the amorphous silicon layer 15 of Example 1 except that the H ₂ partial pressure was 1.4 mTorr and the Ar partial pressure was 6.7 mTorr.

When this configuration was positively charged, the spectral sensitivity remained the same as in Example 1, but the initial charging potential was approximately 400 V, and the charging potential increased.

Example 3 As only a portion is shown in cross section in FIG. 8, an aluminum cylindrical substrate 25 with a mirror-polished surface was placed in a rotary plasma CVD apparatus. Substrate temperature to 250℃
The substrate 25 is rotated at 50 rpm. These gases were introduced into the reaction chamber at a flow rate ratio of B ₂ H ₆ /SiH ₄ = 10 ^-4 and O ₂ /SiH ₄ = 10 ^-4 , and the total pressure was 1 Torr and the discharge power was 5 KW to amorphous. A hydrogenated silicon layer 26 having a thickness of 20 μm was formed. After installing this in a magnetron sputtering device and cleaning the surface by Ar discharge, the Cd _0.4 Zn _0.6 Te layer 27
The same material was targeted and the Ar gas pressure was 5×10 ^-3.
A 4 μm thick film was formed with a discharge power of 200 W in Torr. On top of this, the substrate temperature was set to 200°C in the plasma CVD equipment described above.
N ₂ /SiH ₄ = 5 Total pressure 4Torr, discharge power 1KW
A SiNx layer 28 was formed to a thickness of 0.1 μm. With this configuration, the initial charging potential becomes -350V, resulting in an electrophotographic photoreceptor that can be negatively charged.

In the above example (Cd _x Zn _1-x Te) _1-y (In ₂ Te ₃ )
We have shown an example of amorphous hydrogenated silicon as a charge transport layer for _y , but (Cd _x Zn _1-x Te) _1-y (In ₂ Te ₃ ) _y
Other materials may be used as long as they have a higher electron affinity and allow electrons to travel more easily.

Effects of the Invention According to the present invention, an electrophotographic photoreceptor having high sensitivity in the visible light to near-infrared light region can be obtained. In particular, it has sufficient sensitivity in the near-infrared region compared to conventional electrophotographic photoreceptors, making it suitable as a photoreceptor for laser printers that use semiconductor lasers, and can greatly contribute to speeding up laser printers. .

[Brief explanation of the drawing]

1, 3, 4, and 5 are cross-sectional views showing the basic structure of the electrophotographic photoreceptor of the present invention, and FIG.
The figure is a band diagram of the electrophotographic photoreceptor shown in Figure 1.
b indicates the state of equilibrium, and b indicates the state of positive charging. Figures 6 and 7
8 are sectional views of an electrophotographic photoreceptor according to a specific example of the present invention, and FIG. 9 is a graph showing the spectral sensitivity of the electrophotographic photoreceptor according to the example of FIG. 6. 1... Conductive support, 2... (Cd _x Zn _1-x Te) _1-
y (In ₂ Te ₃ ) _y layer, 3...charge transport layer.

Claims (1)

[Claims] 1 comprises a support having at least a conductive surface, a charge generation layer, and a charge transport layer, wherein the charge generation layer is (Cd _x Zn _1-x Te) _1-y (In ₂ Te ₃ ) _y (O ≦x≦1,
O≦y≦0.1), wherein the charge transport layer is made of a substance having an electron affinity equal to or greater than that of the charge generation layer.