JPS59172650A - Electrophotographic photoconductive layer - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body improved in electrostatic chargeability characteristics and photosensitivity characteristics by specifying a photoconductive layer in the H content, the optical band gap, and its density. CONSTITUTION:An electrophotographic photoconductive layer characteristics amorphous silicon has 20-30 atomic % H content and the absorption coefft. of the absorption peaks at 840, 880, and 2,000cm<-1> of the IR absorption spectra (880), (880), (2,000) satisfy the relationship as shown on the right. Said layer is obtained by forming a photoconductive layer made of amorphous Si or Ge or the like on a substrate by glow discharge decomposition and properly selecting a discharge system, substrate temp., concn. of a material gas, etc. so as to obtain said characteristics of the photoconductive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoconductive layer using amorphous silicon used in an electrophotographic photoreceptor.

Hydrogenated amorphous silicon (IJ lower a-8i:
(abbreviated as H) is usually produced by a glow discharge method or a sputtering method. Since a-8i:H is much superior to conventional materials in terms of heat resistance, abrasion resistance, photosensitivity, etc., its application to electrophotographic photoreceptors has recently attracted attention.

However, the dark resistance of a-2i:H is generally 10'~
It shows a value of 10'Ω・I, which is lower than the dark resistance value of 10I!Ω・Cm or more required for an electron regeneration photoconductor VC.Therefore, the dark decay of the surface potential during corona charging is It is too large to be used as an electrophotographic photoreceptor as it is.

The present invention is an attempt to improve the above-mentioned difficulties.
This has been reached since then.

That is, the gist of the present invention is to provide a photoconductive layer for electrophotography mainly composed of amorphous silicon, which contains 20 to 30 hydrogen atoms and has an infrared scarlet absorption spectrum.
-'', ggo can-1 and 20006m-', the absorption coefficient of the absorption peak satisfies the following formula.

0. /O<ggO)/α(Yoooo Park(gDA0)/α(
yuooo)) (in the formula, α(gl;0), α(ko00θ)
and α(g'lθ) are respectively g g OCm-'
% -20006rlL-' and g'locm-'
The present invention will be described in detail below.

The photoconductive layer containing a-8i:H as a main component can be formed by a glow discharge decomposition method or a sputtering method.

It is formed using a glow discharge decomposition method using a gas such as SiHz or Si*Ha as the main raw material and adding gases such as H3, B, Lu, PL, etc. depending on the purpose. On the other hand, in the sputtering method, S1
An a-8i:H layer is formed by sputtering with Ar ions or the like in a targeted H2 atmosphere.

Formed a-8i:1 (some forms of 5i in the membrane)
-H bond is present. These 5i-H bonds/9? ?
) is shown in Table/.

Among these, the main ones are ggθ~gtis, ggo~g
There are 90, 2000, 209θ ~ Koiooen - small peaks, but the absorption peak is wide <, S~/θl"
-' Since it is difficult to separate the difference, in the present invention, gllo, ggo, +2ooo,
Let each be represented by the center wave number of .

table/ Coupling frequency SiH Yuoooo.

30 Sins 2θ90gg.

30 (SiH,)n 209ON210090 gHiroshi3 Otsu30 Among the above t absorption peaks, g'locm-' is (
Si Ht ) n % g g Oα-' is an isolated S 1
-Hz + (8i Hrin.

200 ocm-' is 81 H, :2090 (H-' is contributed by isolated BiHt(Si-, Ht)n.

In the present invention, regarding the above absorption peak, g'locm
-', the absorption coefficients α(g'IO), α(ggo), and α(koooo) at the angles gθ low 1 and 2000 low −1 are required to satisfy the following equations.

o, /*(ggO)A(koooo bar(gguO)ha(ao
In other words, this formula requires the presence of a specific amount of the isolated 5i-H* acid component.

The absorption coefficient can be calculated using the thickness and transmittance of the thin film obtained at each absorption peak.

The photoconductive layer for electrophotography according to the present invention is obtained by forming a photoconductive layer mainly composed of amorphous silicon (which may further contain amorphous germanium, etc.) by Kf low discharge decomposition on a substrate. This formation is carried out in such a way that the photoconductive layer has the above characteristics.

The substrate is made of metal, such as aluminum, copper, iron,
Nickel, tantalum, stainless steel, etc. (ceramics,
(including those in which metals such as aluminum are added by vapor deposition etc. onto a support made of an organic substance), but silicon, germanium, 1t-rv group, i
-v group semiconductors, organic semiconductors, and other semiconductors may also be used.

First, during glow discharge decomposition, 5inI32n-1
2, etc. in a reduced pressure atmosphere by decomposing the gas by direct current, alternating current, or high frequency method, or
Preferably, a direct current method is employed.

During the above formation, the substrate temperature is 250~. ? It’s.

°C, 51nH Yu. 10, concentration of 50% or more (volume ratio), etc.
'Formation pressure 4100'V ~ 2 kV, current density O1θ/
~/mlv'cA, pressure (during film growth), θ, /~J
'rorr, diborane added as an impurity (&H6
) A range of about 00 ppm (volume ratio) is adopted.

That is, in the present invention, the above-mentioned formation is usually carried out by appropriately selecting and determining the conditions such as the above-mentioned discharge method, substrate temperature, raw material gas temperature, etc., so that the above-mentioned photoconductive layer satisfies the above-mentioned characteristics. Ru.

This formation time varies depending on the physical properties, thickness, etc. of the intended photoconductive layer, but is usually selected from several minutes to about 10 hours.

The photoconductive layer obtained as described above has good charging characteristics and photosensitivity characteristics, and is suitable as an electrophotographic photoreceptor.

Examples will be described below.

Example/ An aluminum substrate and a silicon substrate were mounted on a heater placed in a vacuum container, and used for measuring charging characteristics and infrared absorption spectrum, respectively. Evacuate with a rotary pump for 30 minutes at a substrate temperature above /kO'CIJ. Set the substrate temperature to a predetermined temperature (/!;0.00,230.-g
3.3λs'z), A OVppm by volume ratio
of diborane (BaI(I) and 3.3V% hydrogen gas (H
7) containing silane (5iH4) gas /! rSOC!
Flow M to bring the pressure in the container to about /,OTOrr.

A negative DC high voltage is applied to the substrate to generate a glow discharge between the substrate and the grounded electrode, and the a-8i:H film is deposited on the substrate for about 7 hours. After cooling to below /00'C, the a-sl:H film was released from the container into the atmosphere at a temperature of 7, λ, 9 μm.

When these a-8i:H films are charged with ■ A kV corona discharge, the charging ability (surface potential depending on the film thickness) and dark decay (
Figure 2 shows the dark decay rate of the surface potential per 7 seconds at the initial stage of charging plotted against the value of the isolated 5i-Hp component determined from the infrared absorption spectrum. Isolated 5i-H, component value is 0. It can be seen that the charging characteristics suitable for use as an electrophotographic photoreceptor are exhibited when the value exceeds /.

Example co-substrate temperature is 72! ; °C, da Ovppm B
20.30 silane gas containing H2 in relation to 2H6 and 3θV
, /, 0500M flow, 7 hours of deposition in the same manner as in Example /, 3. ．． 3 /, 5, da, /15, S
, a-8i, :Hjl with a film thickness of 2i μm was used. ■Ak
Charging characteristics during corona charging of V are shown in Figure 2. As is clear from the figure, as the deposition rate increases, the isolated Si
Ht acid component decreased to 0. / If the value exceeds 0, the charging characteristics will be greatly reduced.

Example J The substrate temperature is 3asc, B of Sθ ~ 3θvppm,
To 1105 CC of silane gas containing H, G, 3, U 5
00M H2 was added and allowed to flow, and the film was deposited for 2 hours in the same manner as in Example 1 to obtain a-8i:H films with film thicknesses of 1, 0.5.3, 1, and S μm, respectively. The results of those infrared spectra and ■A kV corona? The characteristics at fF %I are summarized in Table 1.

The charge property was good, and the light sensitivity was constant at 821 ux-sec at the exposure dose to reduce the surface potential by half when a tungsten lamp was used as the light source, showing good sensitivity.

Table 2 α(gggg〃O of .(1,) Imperial charge power dark decay
Photosensitive layer 0, /110. g, 3 2. Da, lI
g, O/, -〇,), '73 /, g Otsu 26
．． 9 3.9 /, 2θ,, 29t 2
．． // 2g4 3.9 Samples (A and B, respectively) formed into films at substrate temperatures of 100° and 150°C in the same manner as in Comparative Example/Example/ had infrared rays as shown in Table 3. characteristics and charging characteristics. ＃Charge property is +A
It was measured with kV corona discharge.

Table 3 Sample A was not charged at all, and sample $8+B was charged, but the dark decay was extremely large.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams showing the relationship between chargeability, dark decay, and 5i-H components.

Claims (1)

[Claims] (1) A photoconductive layer for electrophotography containing amorphous silicon as a main component, (11 hydrogen content in the range of 10 to 3θ atoms,
A photoconductive layer for electrophotography, characterized in that the absorption coefficients of the absorption peaks at 鞞-1 and θo o cm-' satisfy the following formula. (where α(gzaθ), α(2θθθ) and α(gll
θ) are g g ocrn-' and xθoo, respectively.
represents the absorption coefficient of the absorption peak at cxn-' and gttθ 儂-゛)