EP0212581A2 - Couche d'enrichissement pour dispositifs électrophotographiques et procédé pour diminuer la fatigue de charge - Google Patents

Couche d'enrichissement pour dispositifs électrophotographiques et procédé pour diminuer la fatigue de charge Download PDF

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Publication number
EP0212581A2
EP0212581A2 EP86111267A EP86111267A EP0212581A2 EP 0212581 A2 EP0212581 A2 EP 0212581A2 EP 86111267 A EP86111267 A EP 86111267A EP 86111267 A EP86111267 A EP 86111267A EP 0212581 A2 EP0212581 A2 EP 0212581A2
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Prior art keywords
enhancement layer
layer
fabricated
alloy material
approximately
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EP86111267A
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English (en)
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EP0212581A3 (en
EP0212581B1 (fr
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Annette Johncock
Stephen J. Hudgens
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Energy Conversion Devices Inc
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Energy Conversion Devices Inc
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Priority to AT86111267T priority Critical patent/ATE91807T1/de
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Publication of EP0212581A3 publication Critical patent/EP0212581A3/en
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
    • G03G5/08—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic
    • G03G5/082—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic and not being incorporated in a bonding material, e.g. vacuum deposited
    • G03G5/08214—Silicon-based
    • G03G5/08235—Silicon-based comprising three or four silicon-based layers

Definitions

  • This invention relates generally to electrophotographic devices and more particularly to an improved enhancement layer which is specifically tailored to substantially eliminate charge fatigue in electrophotographic photoreceptors by forming the enhancement layer from semiconductor alloy material which has been intentionally doped so as to substantially reduce charge carrier trapping in deep midgap states.
  • the instant invention relates to improved enhancement layers for use in electrophotographic imaging processes.
  • the improved enhancement layer of the instant invention is fabricated from semiconductor alloy material, said material characterized by a decreased number of deep midgap defect sites in which charge carriers can be trapped. By decreasing the number of deep traps the rate of charge carrier emission from taps is increased and the problem of charge fatigue which is prevalent in prior art electrophotographic media is virtually eliminated.
  • Electrophotography also referred to generically as xerography, is an imaging process which relies upon the storage and discharge of an electrostatic charge by a photoconductive material for its operation.
  • a photoconductive material is one which becomes electrically conductive in response to the absorption of illumination; i.e., light incident thereupon, and generates electron-hole pairs (referred to generally as "charge carriers"), within the bulk of the photoconductive material. It is these charge carriers which permit the passage of an electrical current through that material for the discharge of the static electrical charge (which charge is stored upon the outer surface of the electrophotographic media in the typical electrophotographic process).
  • a typical photoreceptor includes a cylindrically- shaped, electrically conductive substrate member, generally formed of a metal such as aluminum. Other substrate configurations, such as planar sheets, curved sheets or metallized flexible belts may likewise be employed.
  • the photoreceptor also includes a photoconductive layer, which, as previously described, is formed of a photoresistive material having a relatively low electrical conductivity in the dark and a relatively high electrical conductivity under illumination. Disposed between the photoconductive layer and the substrate member is a blocking layer, formed either by the oxide naturally occuring on the substrate member, or from a deposited layer of semiconductor alloy material.
  • the blocking layer functions to prevent the flow of unwanted charge carriers from the substrate member into the photoconductive layer in which layer they could then neutralize the charge stored upon the top surface of the photoreceptor.
  • a typical photoreceptor also generally includes a top protective layer disposed upon the photoconductive layer to stabilize electrostatic charge acceptance against changes due to adsorbed chemical species and to improve the photoreceptor durability.
  • a photoreceptor also generally includes a top protective layer disposed upon the photoconductive layer to stabilize electrostatic charge acceptance against changes due to adsorbed chemical species and to improve the photoreceptor durability.
  • a photoreceptor also may include an enhancement layer operatively disposed between the photoconductive layer and the top protective layer, the enhancement layer adapted to substantially prevent charge carriers from being caught in deep traps and hence prevent charge fatigue in the photoreceptor.
  • the electrophotographic photoreceptor accept and retain a high static electrical charge in the dark; it must also provide for the flow of the charge carriers which form that charge from portions of the photoreceptor to the grounded substrate, or from the substrate to the charge portions of the photoreceptor under illumination; and it must retain substantially all of the initial charge for an appropriate period of time in the non-illuminated portions without substantial decay thereof.
  • Imagewise discharge of the photoreceptor occurs through the photoconductive process previously described. However, unwanted discharge may occur via charge injection at the top or bottom surface and/or through bulk thermal charge carrier generation in the photoconductor material.
  • a major source of charge injection is at the metal substrate/semiconductor alloy material interface.
  • the metal substrate provides a virtual sea of electrons available for injection and subsequent neutralization of, for example, the positive static charge on the surface of the photoreceptor. In the absence of any impediment, these electrons would immediately flow into the photoconductive layer; accordingly, all practical electrophotographic media include a bottom blocking layer disposed between the substrate and the photoconductive member.
  • a positive corona charge is placed on the outer surface (the exposed surface of the top protective layer) of the electrophotographic media.
  • the initial reaction of the photoconductive layer of the electrophotographic media to the application of this positive charge to the top surface thereof is to have any free electrons from the bulk be swept toward that surface in an attempt to neutralize the positive charge residing thereon.
  • said electrons encounter deep trap sites such as midgap defect states. While these trap sites are located throughout the bulk of the photoconductive layer, they are of particular importance when they reside near the interface of the photoconductive layer and the top protective layer.
  • the blocking function (the inability of the positive charge carriers electrostatically positioned on the periphery of the top protective layer to penetrate that layer) will cease to be effective - (will "breakdown") when an electrical field of sufficient strength is placed across the top protective layer.
  • a given density of negative charge carriers trapped near the aforementioned interface of the top protective layer and the photoconductive layer will generate a sufficiently strong electrical field across the top protective layer to casue breakdown, whereas the same number of negative charge carriers trapped in the bulk thereof will not.
  • trapping sites located deep in the energy gap of a semiconductor alloy material release trapped charge carriers at a much slower rate than do sites located closer to one of the bands. This results from the fact that more thermal energy is required, for example, to re-excite. a trapped electron from the deep sites which exist near the middle of the energy gap to the conduction band than is required to re-excite an electron from the shallower sites which exist closer to the conduction band.
  • the slow release rate from deep traps gives rise to a higher equilibrium trap occupancy and thus a higher electric field distribution.
  • the photoconductive layer thereof is made from a "pi-type" silicon:fluorine:hydrogen:boron alloy.
  • pi-type will refer to semiconductor alloy material, the Fermi level of which has been displaced from its undoped position closer to the conductive band to a position approximately "midgap”.
  • midgap will be used to define a point in the energy gap of a semiconductor alloy material which is positioned approximately half-way between the valence band and the conductive band (in the case of 1.8 eV amorphous silicon:fluroine:hydrogen:boron alloy this is about 0.9 eV from each of the bands).
  • the enhancement layer of said aforementioned application relied upon a reduction in the overall density of defect states present in undoped semiconductor alloy material to aid in reducing the number of deep traps in which charge carriers could be caught in order to reduce charge fatigue.
  • no attempt or even suggestion of how.to optimize the chemical composition of the enhancement layer in order to further prevent charge carriers from being caught in the deep midgap traps was discussed or suggested in said application.
  • An important advantage obtained by following the teachings of the present invention resides in the optimization of the enhancement layer so as to prevent charge carrier fatigue and improve the operational cycling time of electrophotographic devices incorporating said optimized enhancement layer. Moreover, by utilizing the disclosure found herein, charge carriers are substantially inhibited from falling into the deep midgap traps. Only relatively shallow defect states remain in which charge carriers may be trapped and the rate of emission of charge carriers from these shallow traps can be measured in terms of seconds rather than in terms of days. Therefore, in its broadest form, the present application relates to the positioning of the Fermi level of the semiconductor alloy material from which the enhancement layer is formed to a position above midgap. This results in the deep mid- gap states being occupied by electrons and thus not being effective as electron traps.
  • Mort, et al proposed the addition of a boron- doped trapping layer interposed between the top surface of the photoconductive layer and the insulating layer (the top protective layer) for quenching the effects of the electric field and removing the effect of "field-inducing blurring” (commonly referred to as "image-flow"). In this manner, Mort, et al were able to counteract the problem of "image-flow”.
  • Mort, et al were not concerned with and failed to address the concurrently present problem of "charge fatigue". Moreover, Mort, et al, by adding boron dopant, shifted the Fermi level of the semiconductor alloy material toward the valence band. By so shifting the Fermi level of the semiconductor alloy material, they inherently caused electrons, attempting to move to the conduction band, to pass through the deep midgap states which are responsible for the problem of charge fatigue and which the subject application attempts to avoid. Note that Mort, et al specifically prohibit the use of phosphorous doping to shift the Fermi level of the enhancement layer toward the conduction band because such a shift would make the semiconductor alloy material thereof more conductive, thereby causing just the type of lateral electron flow they seek to avoid.
  • Applicants first intentionally phosphorous doped the semiconductor alloy material of the enhancement layer which is interposed between the photoconductive layer and the top protective layer in order to shift the Fermi level thereof toward the conduction band.
  • the electrons do not have to move through and become caught in the deep midgap states present in the energy gap thereof.
  • This substantially eliminates the problems of charge fatigue by keeping the electrons out of the deep midgap states.
  • Applicants then introduce both boron dopant and phosphorus dopant so as to pin the Fermi level at that preselected position in the energy gap through the addition of defect states on both sides of the pinned Fermi level.
  • the added defect states being shallow, not only solve charge fatigue problems, but those states are sufficiently numerous to inhibit lateral electron flow, quench the field effect and hence simultaneously solve image flow problems.
  • amorphous is defined to include alloys or materials exhibiting long range disorder, although said alloys or materials may exhibit short or intermediate range order or even contain crystalline inclusions.
  • microcrystalline is defined as a unique class of said amorphous materials characterized by a volume fraction of crystalline inclusions, said volume fraction of inclusions being greater than a threshold value at which the onset of substantial changes in certain key parameters such as electrical conductivity, band gap and absorption constant occur. It is to be noted that pursuant to the foregoing definitions, the microcrystalline, materials employed in the practice of the instant invention fall within the generic term "amorphous" as defined hereinabove.
  • electrophotographic media comprising an electrically conductive substrate, a bottom layer overlying the substrate which is adapted to block the free flow of charge carriers from the substrate, a photoconductive layer overlying the bottom layer which is adapted to discharge an electrostatic charge, an enhancement layer overlying the photoconductive layer which is adapted to substantially reduce the number of charge carriers caught in deep midgap traps, said enhancement layer formed of intentionally doped semiconductor alloy material and a top protective layer overlying the enhancement layer which is adapted to protect the photoconductive layer from ambient conditions and aid in the transport of charge carriers under illumination.
  • the bottom blocking layer is preferably formed of a doped microcrystalline semiconductor alloy material which is selected from the group consisting essentially of chalcogens, amorphous silicon alloys, amorphous germanium alloys, amorphous silicon-germanium alloys, photoconductive organic polymers and combinations thereof.
  • the enhancement layer is preferably fabricated from a material selected from the group consisting essentially of amorphous silicon alloys, amorphous germanium alloys and amorphous silicon-germanium alloys.
  • the enhancement layer is yet more favorably fabricated from an amorphous silicon alloy and the Fermi level thereof is moved to within 0.5 to 0.8 eV of the conduction or valence band.
  • the Fermi level of the enhancement layer is moved to within 0.65 to 0.75 eV of the conduction or valence band.
  • the enhancement layer is fabricated from a material which has been specifically tailored so as to provide for the thermal emission of charge carriers from traps at the interface thereof with the top protective layer in approximately one second or less.
  • the thickness of the enhancement layer is approximately 2,500 to 10,000 angstroms and preferably about 5,000 angstroms.
  • the Fermi level of the enhancement layer may be pinned at a given location from the conduction band. The pinning of the Fermi level may be accomplished by including both phosphorus and boron, in the semiconductor alloy matrix for adding shallow states at the energy gap of the semiconductor matrix so as to pin said Fermi level at a preselected position.
  • a method of preventing charge fatigue in electrophotographic media of the type which include an electrically conductive substrate, a bottom charge injection blocking layer, a photoconductive layer and a top protective layer.
  • the method includes the steps of forming an enhancement layer from an intentionally doped semiconductor alloy material and operatively disposing said enhancement layer between the photoconductive layer and the top protective layer so that the enhancement layer is adapted to substantially decrease the number of charge carriers caught in deep midgap traps as charge carriers approach the interface between said enhancement layer and the top protective layer.
  • the method includes the further steps of forming the back blocking layer from a microcrystalline, boron doped silicon:hydrogen:fluorine alloy, the extent of boron doping being sufficient to make the material degenerate and (2) forming the enhancement layer from a material selected from the group consisting essentially of amorphous silicon alloys, amorphous germanium alloys and amorphous silicon-germanium alloys.
  • the further step is included of moving the Fermi level of the enhancement layer to within 0.5 to 0.8 eV of the conduction or valence band and preferably to within 0.65 to 0.75 eV of the band.
  • the material from which the enhancement layer is fabricated is tailored so as to provide for the emission of charge carriers from said traps in approximately one second or less.
  • the method may still include the further step of forming the enhancement layer to be approximately 2,500 to 10,000 angstroms thick and preferably approximately 5,000 angtroms thick.
  • the Fermi level of the semiconductor alloy material from which the enhancement layer is fabricated is pinned by introducing both boron and phosphorus, into the host semiconductor matrix thereof so as to add additional shallow states at both sides of the Fermi level in the energy gap thereof.
  • the photoreceptor 10 includes a generally cylindrically shaped substrate 12 formed, in this embodiment, of aluminum, although other nondeformable metals such as stainless steel could also be employed as a preferred embodiment.
  • the periphery of the aluminum substrate 12 is provided with a smooth, substantially defect free surface by any well known technique such as diamond machining and/or polishing.
  • a doped layer 14 of microcrystalline semiconductor alloy material Disposed immediately atop the deposition surface of the substrate 12 is deposited a doped layer 14 of microcrystalline semiconductor alloy material which has been specifically designed and adapted to serve as the bottom blocking layer for said photoreceptor 10.
  • the blocking layer 14 is formed of highly doped, highly conductive microcrystalline semiconductor alloy material.
  • the photoconductive layer 16 Disposed immediately atop the bottom blocking layer 14 is the photoconductive layer 16 which may be formed from a wide variety of photoconductive materials. Among some of the preferred materials are doped intrinsic amorphous silicon alloys, amorphous germanium alloys, amorphous silicon-germanium alloys, chalcogenide materials and organic photoconductive polymers.
  • the improved enhancement layer 18 of the subject invention Disposed atop the photoconductive layer 16 is the improved enhancement layer 18 of the subject invention, said enhancement layer specifically designed to substantially reduce the problem of charge fatigue described in the Background section of this specification.
  • the photoreceptor 10 includes a top protective layer 19 operatively disposed atop the enhancement layer 18, which protective layer 19 (1) protects the upper surface of the photoconductive layer 16 from ambient conditions and (2) separates the charge stored on the surface of the photoreceptor 10 from carriers generated in the photoconductive layer 16.
  • the improved enhancement layer 18 is formed of an intentionally doped semiconductor alloy material.
  • the purpose of intentionally doping the enhancement layer 18 is to move the Fermi level closer to the conduction band (in the case of a positive corona charge) of the semiconductor alloy material from which said layer is fabricated.
  • semiconductor alloy materials may be employed from which to fabricate the enhancement layer 18.
  • silicon:hydrogen alloys silicon:hydrogen:halogen alloys, germanium:hydrogen alloys, germanium:hydrogen:halogen alloys, silicon:germanium:hydrogen alloys, and silicon:hydrogen:halogen alloys.
  • fluorinated alloys are particularly preferred.
  • Doping of the semiconductor alloy material may be accomplished by any technique and employing any material which is well known to those of ordinary skill in the art. Because Applicants' previous enhancement layers, as described in said patent application Serial No. 580,081, were prepared with a reduced density of defect states, the charge carriers moving through that layer from the photoconductive layer 16 to neutralize charge located at the surface of the top protective layer 19 were not caught in as many deep midgap traps. The result was a reduction in the number of carriers which required the aforedescribed lengthy period of time required to be emitted from the deep traps.
  • the Fermi level of which is moved to a desired location and pinned so that charge carriers are able to avoid the deep midgap states present in the silicon alloy material from which the layer is fabricated
  • the residency time of charge carriers caught in traps is significantly decreased since only the traps accessible to the carriers are shallow traps.
  • the absence of deep trapped carriers not only prevents a breakdown of the top protective layer 20, but significantly increases the cycle time in which the electrophotographic medium 10 is capable of recovering lost surface charge and readying itself for reproducing a further copy.
  • the amorphous silicon alloys, amorphous germanium alloys and amorphous-silicon germanium alloys were found to be particularly advantageous. Such alloys and methods for their preparation are disclosed in the patents and applications referred to and incorporated by reference hereinabove.
  • the conductivity type of the materials from which the blocking layer 14 and the photoconductive layer 16 are fabricated are chosen so as to establish a blocking contact therebetween whereby injection of unwanted charge carriers into the bulk of the photoconductive layer 16 is effectively inhibited.
  • the bottom blocking layer 14 will preferably be fabricated from a heavily p-doped alloy and the photoconductive layer 16 will be fabricated from an intrinsic semiconductor layer, an n-doped semiconductor layer or a lightly p-doped semiconductor layer. Combinations of these conductivity types will result in the substantial inhibition of electron flow from the substrate 12 into the bulk of the photoconductor layer 16.
  • intrinsic, or lightly doped semiconductor layers are generally favored for the fabrication of the photoconductive layer 16 insofar as such materials will have a lower rate of thermal charge carrier generation than will more heavily doped materials.
  • Layers of intrinsic semicondcutor alloy materials are most preferably favored insofar as such layers have the lowest number of defect states per unit volume and the most favorable discharge characteristics.
  • the maximum electrostatic voltage which the photoreceptor 10 can sustain (V sat) will depend upon the efficiency of the blocking layer 14 as well as the thickness of the photoconductive layer 16. For a given blocking layer efficiency, a photoreceptor 10 having a thicker photoconductive layer 16 will sustain a greater voltage. For this reason, charging capacity or charge acceptance is generally referred to in terms of volts per micron thickness of the photoconductive layer 16. For economy of fabrication and elimination of stress it is generally desirable to have the total thickness of the photoconductive layer 16 be 25 microns or less. It is also desirable to have as high a static charge maintained thereupon as possible. Accordingly, gains in barrier layer efficiency, in terms of volts per micron charging capacity, translate directly into improved overall photoreceptor performance. It has routinely been found that photoreceptors structured in accordance with the principles of the instant invention are able to sustain voltages of greater than 50 volts per micron on up to a point nearing the dielectric breakdown of the semiconductor alloy material.
  • the intentionally doped semiconductor alloy material of the enhancement layer of the instant invention is produceable by a wide variety of deposition techniques, all of which are well known to those skilled in the art.
  • Said deposition techniques include, by way of illustration, and not limitation, chemical vapor deposition techniques, photoassist- ed chemical vapor deposition techniques, sputtering, evaporation, electroplating, plasma spray techniques, free radical spray techniques, and glow discharge deposition techniques.
  • glow discharge deposition techniques have been found to have particular utility in the fabrication of the enhancement layer of the instant invention.
  • a substrate is disposed in a chamber maintained at less than atmospheric pressure.
  • a process gas mixture including a precursor of the semiconductor alloy material (and dopants) to be deposited is introduced into the chamber and energized with electromagnetic energy.
  • the electromagnetic energy activates the precursor gas mixture to form ions and/or radicals and/or other activated species thereof which species effect the deposition of a layer of semiconductor material upon the substrate.
  • the electromagnetic energy employed may be dc energy, or ac energy such as radio frequency or microwave energy.
  • FIG. 2 there is illustrated a cross-sectional view of one particular apparatus 20 adapted for the microwave energized deposition of layers of semiconductor material onto a plurality of cylindrical drums or substrate members 12. It is in an apparatus of this type that the electrophotographic photoreceptor 10 of Figure 1 may be advantageously fabricated.
  • the apparatus 20 includes a deposition chamber 22, having a pump-out port 24 adapted for suitable connection to a vacuum pump for removing reaction products from the chamber and maintaining the interior thereof at an appropriate pressure to facilitate the deposition process.
  • the chamber 22 further includes a plurality of reaction gas mixture input ports 26, 28 and 30 through which reaction gas mixtures are introduced into the deposition environment.
  • the chamber 22 supports a plurality of cylindrical drums or substrate members 12.
  • the drums 12 are arranged in close proximity, with the longitudinal axes thereof disposed substantially mutually parallel and the outer surfaces of adjacent drums being closely spaced apart so as to define an inner chamber region 32.
  • the chamber 22 includes a pair of interior upstanding walls, one of which is illustrated at 34. The walls support thereacross a plurality of stationary shafts 38.
  • Each of the drums 12 is mounted for rotation on a respective one of the shafts 38 by a pair of disc shaped spacers 42 having outer dimensions corresponding to the inner dimension of the drums 12, to thereby make frictional engagement therewith.
  • the spacers 42 are driven by a motor and chain drive, not shown, so as to cause rotation of the cylindrical drums 12 during the coating process for facilitating uniform deposition of material upon the entire outer surface thereof.
  • the drums 12 are disposed so that the outer surfaces thereof are closely spaced apart so as to form the inner chamber 32.
  • the reaction gases from which the deposition plasma will be formed are introduced into the inner chamber 32 through at least one of the plurality of narrow passages 52 formed between a given pair of adjacent drums 12.
  • the reaction gases are introduced into the inner chamber 32 through every other one of the narrow passages 52.
  • each pair of adjacent drums 12 is provided with a gas shroud 54 connected to one of the reaction gas input ports 26, 28 and 30 by a conduit 56.
  • Each shroud 54 defines a reaction gas reservoir 58 adjacent to the narrow passage through which the reaction gas is introduced.
  • the shrouds 54 further include lateral extensions 60 which extend from opposite sides of the reservoir 58 and along the circumfrence of the drums 12 to form narrow channel 62 between the shroud extension 60 and the outer surfaces of the drums 12.
  • the shrouds 54 are configured as described above so as to assure that a large percentage of the reaction gas will flow into the inner chamber 32 and maintain uniform gas flow along the entire lateral extent of the drums 12.
  • narrow passages 66 which are not utilized for reaction gas introduction into the chamber 32 are utilized for removing reaction products from the inner chamber 32.
  • the pump coupled to the pump out port 24 is energized, the interior of the chamber 22 and the inner chamber 32 is pumped out through the narrow passages 66. In this manner reaction products can be extracted from the chamber 22, and the interior of the inner chamber 32 can be maintained at a suitable pressure for deposition.
  • the apparatus further includes a microwave energy source, such as a magnetron with a waveguide assembly or an antenna, disposed so as to provide microwave energy to the inner chamber 32.
  • a microwave energy source such as a magnetron with a waveguide assembly or an antenna
  • the apparatus 20 includes a window 96 formed of a microwave permeable material such as glass or quartz.
  • the window 94 in addition to enclosing the inner chamber 32, allows for disposition of the magnetron or other microwave energy source exteriorly of the chamber 22, thereby isolating it from the environment of the process gas mixture.
  • the apparatus 20 may further include a plurality of heating elements, not shown, disposed so as to heat the drums 12.
  • the drums are generally heated to a temperature between 20°C and 400°C and preferrably about 225°C.
  • an electrophotographic photoreceptor was fabricated in a microwave energized glow discharge deposition system generally similar to that depicted with reference to Figure 2.
  • a cleansed aluminum substrate was first operatively positioned in the deposition apparatus and then the chamber was evacuated and a gas mixture comprising .15 SCCM (standard cubic centimeters per minute) of a 10.8% mixture of BF, in hydrogen; 75 SCCM of 1000 ppm SiH. in hydrogen and 45 SCCM of hydrogen was introduced thereinto..
  • the pumping speed was constantly adjusted to maintain a total pressure of approximately 100 microns in the chamber while the substrate was maintained at a temperature of approximately 300°C.
  • a bias of +80 volts was established by disposing a charged wire in the plasma region.
  • Microwave energy of 2.45 GHz was introduced into the deposition region. These conditions resulted in the deposition of the bottom blocking layer of boron doped microcrystalline silicon:hydrogen:fluorine alloy material. The deposition rate was approximately 20 Angstroms per second and the deposition continued until the boron doped microcrystalline blocking layer obtained a total thickness of approximately 7500 Angstroms.
  • a top protective layer of an amorphous silicon:carbon:hydrogen:fluorine alloy is deposited atop the improved enhancement layer.
  • a gas mixture comprising 2 SCCM of SiH., 30 SCCM of CH. and 2 SCCM of SiF. is introduced into the deposition apparatus for depositing this layer.
  • the microwave energy source is energized and deposition of a layer of amorphous silicon:hydrogen:fluorine:carbon occured at a rate of approximately 40 Angstroms per second. Deposition continued until approximately 5000 Angstroms of the protective layer was deposited at which time the microwave energy was terminated, the substrate was cooled to 100°C, the apparatus was raised to atmospheric pressure and the thus prepared electrophotographic photoreceptor was removed for testing.
  • the foregoing process could be modified to fabricate a photoreceptor adapted for negative charging by merely substituting opposite dopants in roughly equimolar quantities. That is to say, the bottommost blocking layer would be a phosphorous doped layer; the photoconductive layer would be inrinsic or slightly phosphorous doped; the enhancement layer would have its Fermi level positioned and pinned within 0.65 to 0.75 eV of the valence band.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
EP86111267A 1985-08-26 1986-08-14 Couche d'enrichissement pour dispositifs électrophotographiques et procédé pour diminuer la fatigue de charge Expired - Lifetime EP0212581B1 (fr)

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AT86111267T ATE91807T1 (de) 1985-08-26 1986-08-14 Anreicherungsschicht fuer elektrophotographische anlagen und verfahren zum verringern von ladungsmuedigkeit.

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US76910685A 1985-08-26 1985-08-26
US769106 1985-08-26

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EP0212581A2 true EP0212581A2 (fr) 1987-03-04
EP0212581A3 EP0212581A3 (en) 1988-09-28
EP0212581B1 EP0212581B1 (fr) 1993-07-21

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EP (1) EP0212581B1 (fr)
JP (1) JPH0797228B2 (fr)
AT (1) ATE91807T1 (fr)
CA (1) CA1271076A (fr)
DE (1) DE3688723T2 (fr)
IN (1) IN166164B (fr)

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JPS5888753A (ja) * 1981-11-24 1983-05-26 Oki Electric Ind Co Ltd 電子写真感光体
US4418132A (en) * 1980-06-25 1983-11-29 Shunpei Yamazaki Member for electrostatic photocopying with Si3 N4-x (0<x<4)
US4471042A (en) * 1978-05-04 1984-09-11 Canon Kabushiki Kaisha Image-forming member for electrophotography comprising hydrogenated amorphous matrix of silicon and/or germanium
GB2145530A (en) * 1983-08-23 1985-03-27 Sharp Kk Amorphous silicon photoreceptor
EP0137516A2 (fr) * 1983-10-13 1985-04-17 Sharp Kabushiki Kaisha Photorécepteur constitué de silicium amorphe
EP0141664A2 (fr) * 1983-11-02 1985-05-15 Xerox Corporation Dispositif électrographique photosensible
EP0151754A2 (fr) * 1984-02-14 1985-08-21 Energy Conversion Devices, Inc. Procédé de fabrication d'un élément photoconducteur

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Publication number Priority date Publication date Assignee Title
JPS6059367A (ja) * 1983-08-19 1985-04-05 ゼロツクス　コーポレーシヨン 調整した無定形ケイ素を含む電子写真装置
JPS60153051A (ja) * 1984-01-20 1985-08-12 Toshiba Corp 光導電部材

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4471042A (en) * 1978-05-04 1984-09-11 Canon Kabushiki Kaisha Image-forming member for electrophotography comprising hydrogenated amorphous matrix of silicon and/or germanium
US4418132A (en) * 1980-06-25 1983-11-29 Shunpei Yamazaki Member for electrostatic photocopying with Si3 N4-x (0<x<4)
JPS5888753A (ja) * 1981-11-24 1983-05-26 Oki Electric Ind Co Ltd 電子写真感光体
GB2145530A (en) * 1983-08-23 1985-03-27 Sharp Kk Amorphous silicon photoreceptor
EP0137516A2 (fr) * 1983-10-13 1985-04-17 Sharp Kabushiki Kaisha Photorécepteur constitué de silicium amorphe
EP0141664A2 (fr) * 1983-11-02 1985-05-15 Xerox Corporation Dispositif électrographique photosensible
EP0151754A2 (fr) * 1984-02-14 1985-08-21 Energy Conversion Devices, Inc. Procédé de fabrication d'un élément photoconducteur

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, vol. 7, no. 188 (P-217)[1333], 17th August 1983; & JP-A-58 088 753 (OKI DENKI KOGYO K.K.) 26-05-1983 *

Also Published As

Publication number Publication date
EP0212581A3 (en) 1988-09-28
IN166164B (fr) 1990-03-24
CA1271076A (fr) 1990-07-03
ATE91807T1 (de) 1993-08-15
JPS6270853A (ja) 1987-04-01
EP0212581B1 (fr) 1993-07-21
DE3688723D1 (de) 1993-08-26
DE3688723T2 (de) 1993-10-28
JPH0797228B2 (ja) 1995-10-18

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