JPH06204550A - Photoelectric conversion element and image reading device using same - Google Patents

Abstract

PURPOSE:To control an electric field of a TFT type sensor and to improve photocurrent sensitivity by specifying the relationship between a distance between drain/source electrodes of a photoelectric conversion element having an auxiliary electrode for an electric field control and an effective film thickness determined in consideration of the permittivity of a semiconductor layer and an insulating layer. CONSTITUTION:First the relationship between a drain/source distance (ds) and an effective film thickness (d) determined in consideration of the permittivity of a semiconductor layer 4 and an insulating layer 3 is set to be d/Lds > 1/6. Then, a gate electrode 2 is formed selectively on an insulative substrate 1 and, in succession, an amorphous silicon hydride nitride film to be a gate insulation film 3, an intrinsic amorphous silicon hydride to be the semiconductor layer 4 and an N<+> layer 5 being an ohmic contact layer are deposited sequentially. Thereafter source and drain electrodes 6 and 7 are deposited and a photosernsitive resist for patterning is applied. With this used as a mask, each electrode and the N<+> layer 5 are etched and a protective layer 8 of a silicon nitride film is formed on the surface of a thin-film semiconductor thus formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion element and an image reading apparatus using the same, and more particularly to a facsimile apparatus,
The present invention relates to a photoelectric conversion element and an image reading device which are preferably used in a digital copying machine or the like.

[0002]

2. Description of the Related Art In recent years, in order to reduce the size and improve the performance of facsimiles, image readers, etc., a long line sensor having an equal magnification optical system has been actively developed as a photoelectric conversion device. Furthermore, in order to further reduce the size and cost, a perfect contact photoelectric conversion in which the sensor directly detects the reflected light from the original through a transparent spacer such as glass without using the same-magnification fiber lens array. Equipment is also being developed.

FIG. 11 is a schematic sectional view of such a perfect contact type photoelectric conversion device as seen from the main scanning direction. In addition,
Since a detailed description of the perfect contact photoelectric conversion device will be given in the embodiments of the present invention, only the basic configuration will be described here.

In this perfect contact type photoelectric conversion device,
Photoelectric conversion unit 112, charge storage unit 113, charge transfer unit 11
The thin film transistor (hereinafter, referred to as TFT) 4 and the wiring 111 which are 4 are formed in the same process, which enables the manufacturing by a simple process.

In the perfect contact type photoelectric conversion device, for the light receiving semiconductor layer 22, the light from the light source is emitted from the substrate 21 side.
Light reflected from the document enters from the electrodes 24, 24 'in the opposite direction. In order to detect only the reflected light from the document, it is necessary to provide an opaque layer between the light source and the light receiving semiconductor layer 22. Further, if the opaque layer is made of metal, a constant potential is applied, and the semiconductor layer is in contact with the semiconductor layer with the insulating layer interposed therebetween, the Fermi level of the semiconductor is also stabilized. For such a purpose, a photoelectric conversion element having the auxiliary electrode 25 is used for the photoelectric conversion unit 112. Since such a photoelectric conversion element has a TFT structure, it is called a TFT type optical sensor. The electrodes 24 and 24 'will be described as drain and source electrodes, and the auxiliary electrode 25 as a gate electrode.

As described above, the TFT type optical sensor has many advantages as an optical sensor such that it is suitable for stabilizing and completely adhering the semiconductor layer and can be easily manufactured in the same process as the storage and transfer system.

[0007]

However, when the TFT type optical sensor is viewed from the aspect of characteristics, there is no gate (gate electrode 1
There is a serious drawback that the photocurrent is smaller by one digit to two digits than the photoconductive type (secondary photocurrent type) photosensor, which does not have No. Due to this small photocurrent, the signal processing becomes complicated, or when the signal charge is stored in a capacitor and converted into a voltage, a long storage time is required, or a light source with high illuminance is required. There was a problem.

Here, the mechanism of the photocurrent of the photoconductive type (secondary photocurrent type) photosensor including the TFT type will be briefly described. Here, the semiconductor layer is an intrinsic hydrogenated amorphous silicon layer, and the n ⁺ layer is used for the ohmic connection between the semiconductor and the electrode, and the carriers of the secondary photocurrent are electrons, and holes are holes. Are blocked at the n ⁺ layer.

When a bias is applied and the device, which has been placed in the dark state, is irradiated with light, the generation of electron-hole pairs is started. The generated carriers are partly captured by the trap, partly travels by the electric field, and partly recombines and disappears. Of the traveling carriers, electrons can leave the drain electrode, but holes are blocked by the n ⁺ layer and are confined in the device. A secondary current is injected from the source electrode to electrically neutralize the accumulation of this positive charge in the device.

The amount of positive charges accumulated in the device will be described with reference to FIG. In general, the recombination rate R (t) of amorphous silicon has an electron existing in the conduction band, an electron trapped in the conduction band side tail state, a hole existing in the valence band, and a hole trapped in the valence band side tail state. , Or Fermi level. Therefore, the recombination rate after the start of light irradiation does not reach a steady value until the time Ton when the incremental carriers due to light are rearranged to these levels, and at the same time as the incidence of light, the number of carriers corresponding to the number of incident photons is increased. It has a slower time constant than the rate generated. That is, the time Ton at which the light irradiation equilibrium state is reached is the time required for the device to respond to light.

From the start of light irradiation to the time Ton, the increment due to generation is larger than the disappearance due to recombination. Therefore, the difference between carriers is accumulated in the device by being trapped in the trap. The rate of change of the number. The integrated value of this difference from the start of light irradiation to the time Ton is
It is the total amount Nht of positive charges trapped in the device in the light irradiation equilibrium state.

[0012]

[Equation 1] Now, since the holes are blocked by the n ⁺ layer between both electrodes and the semiconductor, the entry and exit from the device are increments due to photo-generated electron hole generation and decrements due to electron-hole pair recombination. In the light irradiation equilibrium state, the amount of holes in the device is constant, so that generation and recombination occur at the same rate. Since both generation and recombination occur in pairs of electrons and holes, it can be considered that even in electrons, generation and recombination in the entire device occur at the same rate. That is,
In the light irradiation equilibrium state, it can be considered that all the generated electrons disappear by recombination and do not contribute to the photocurrent.

Considering the charge neutral condition in the device,
There must be a quantity of electrons in the device equal to the quantity Nht of holes accumulated by the time Ton.
The electrons can be considered in two states for convenience. That is, the electrons accumulated in the device by a trap or the like and the traveling electrons. Of these, the electrons that contribute to the secondary photocurrent are the latter traveling electrons. Let Nec be the total number of electrons trapped in the device, Net be the total number of electrons traveling in the device, and Te be the average time taken by the traveling electrons from the source electrode to the drain electrode. Since Ip is the amount of electric charge that passes through per unit time, it can be expressed as Nec = Nht-Net formula (2) Ip = e × Nec / Te formula (3) e: elementary charge amount of electron.

From the above discussion, under constant light irradiation,
In order to obtain a larger photocurrent without deteriorating the optical response, it is clear that shortening the transit time between the drain and the source of the injected carriers (electrons in the above example) is important. .

In order to shorten the traveling time, the mobility μ of the traveling electrons is increased, the drain-source electric field for traveling is increased, or the drain-source distance that must travel. (Hereafter, Lds
That is) small.

Regarding the matter of increasing the mobility μ, the physical properties of the film quality itself of the semiconductor layer are dominant, and the film forming conditions, the device for manufacturing the film, etc., or the post-treatment by plasma, light, heat, etc. Various studies are continuing.

Next, the drain-source electric field will be described. Hereinafter, the potential difference between the drain and the source is Vds. FIG. 20 shows a TFT type sensor with Lds = 10 μm, Vg
The dependence of the photocurrent Ip and the dark current Id on Vds in the operation at s = 0 V is shown. The photocurrent Ip increases as Vds increases, but Vds / Lds> 1.
In the region of 0 V / μm, the dark current Id rapidly increases due to the space limiting current, and the S / N ratio with the photocurrent Ip deteriorates. At high temperature operation of 55 ° C, the S / N ratio is the dark current I
It is further aggravated by the temperature characteristic of d. Therefore, for example, in a TFT sensor with Lds = 10 μm, Vds
Has to be used in the region of 10 V or less, and there is a limit to increase Vds.

Further, there is a limit to the reduction of Lds due to device manufacturing conditions for performing the photolithography process for forming the source and drain electrode shapes in a stable and high yield. When a line sensor is manufactured by arranging photosensors at a density of 8 pixels / mm in a length corresponding to the document width of A4 to B4, at present, this limit is about 8 μm in terms of productivity. That is, from the breakdown voltage due to the space limiting current and the limit on the photolithography process side, V of the TFT type optical sensor device is
There is a limit to increase ds / Lds.

As described above, the TFT type optical sensor has a problem that the photocurrent is small for the optical response, which has been an obstacle to the realization of a high-speed and inexpensive image reading apparatus.

[0020]

In order to solve the above problems, the present invention has an effective film thickness d in which the drain-source distance Lds in a TFT type sensor and the dielectric constants of a semiconductor layer and an insulating layer are taken into consideration. It has been found that the relationship between Ls and d is essential in designing a band structure, and the relationship between Lds and d is set to a region of d / Lds> 1/6, which has not been used in the past, so that the electric field of the TFT optical sensor is To improve the photocurrent sensitivity.

[0021]

The function of the present invention will be described below. In addition,
The conventional TFT type sensor will be described assuming that Lds is 10 μm.

FIG. 14 shows the Vgs dependency of the photocurrent Ip and the dark current Id of the TFT type sensor, and FIG. 15 shows the Vgs dependency of the index γp (1 is ideal) of the illumination light intensity dependency.
As is clear from both figures, as the Vgs shifts from the negative to the positive region, the S / N ratio sharply decreases, and the γp characteristic is 1
It greatly deviates from, and comes to show an operation that cannot be used as an optical sensor. For this reason, the gate potential Vgs of the TFT photosensor is operated in the negative region of 0 V or less.

However, at this operating potential, most of the drain-source electric field is applied to the semiconductor layer in the region near the drain. FIG. 16 shows the electric field distribution in the dark state in the device obtained by simulation. With this electric field distribution, the electrons injected from the source electrode exist in the low electric field region for most of the time, and a sufficient traveling speed cannot be obtained. In the electric field distribution obtained by the above simulation, it was found that the transit time was about 30 times longer than that of the sensor without gate in which the drain-source electric field was applied almost uniformly to the semiconductor layer. This is considered to be a major reason why the photocurrent of the TFT type photosensor is smaller by one digit to two digits than that of the photoconductive type photosensor without a gate.

That is, in order to shorten the transit time of electrons, it suffices to correct the non-linearity of the electric field between the drain and the source (hereinafter, this is referred to as linearization of the electric field).
As is apparent from FIG. 16, the reason for the distortion of the electric field between the drain and the source is that there is a gate electrode that is given a potential equal to or lower than that of the source electrode at a distance far closer to the source electrode as viewed from the drain electrode. It is to be. That is, the simplest method for linearizing the drain-source electric field is to increase the distance from the drain electrode to the gate electrode in relation to the distance from the drain electrode to the source electrode.

17 and 18 show Lds / Te showing the linearity of the electric field in the device calculated by using the equivalent film thickness d and Lds as parameters in the above-mentioned simulation. The equivalent film thickness d is the series of the capacitance C (SiN) per unit area of the silicon nitride portion and the capacitance C (i) per unit area of the semiconductor layer portion, expressed by the following equations (4) to (7). Is a film thickness of the equivalent capacitor obtained by replacing the equivalent capacitor C with the dielectric constant of the semiconductor layer. The effective film thickness d in consideration of the dielectric constants of the semiconductor layer and the insulating layer in the present application is the equivalent film thickness d.

1 / C = 1 / C (SiN) + 1 / C (i) Formula (4) C (SiN) = ε (SiN) / d (SiN) Formula (5) C (i) = ε (i) / D (i) Formula (6) C = ε (i) / d Formula (7) ε (SiN): Silicon nitride film dielectric constant ε (i): i layer dielectric constant As is apparent from FIGS. 17 and 18. , Lds / Te is
It increases as d increases or Lds decreases,
It shows that the non-linearity of the electric field is corrected. As a matter of course, in the photosensor without a gate electrode in which the electric field between the drain and source electrodes is applied almost linearly, Lds / Te was constant with respect to the increase or decrease of d or Lds.

[0027]

Embodiments of the present invention will now be described with reference to the drawings. (First Embodiment) FIG. 1 is a sectional view of a TFT type optical sensor of the present invention. First, a method for manufacturing the TFT type optical sensor of the present invention shown in FIG. 1 will be described.

(1) The gate electrode 2 is formed of Cr on the insulating substrate 1.
A hydrogenated amorphous silicon nitride film (a-SiNx: H, hereinafter referred to as a silicon nitride film) to be the gate insulating film 3 and an intrinsic hydrogenated amorphous silicon (hereinafter referred to as a-to be the semiconductor layer 4). Si: H
Hereinafter), an ohmic contact layer serving n ⁺ layer 5, by a plasma CVD method are sequentially deposited. Conventional 3000 Å
The film thickness of the silicon nitride film was 1000Å, 3000
Å, 6000Å, conventional 6500Å a-Si: H
The film thickness was set to 3000 Å, 6500 Å, and 10000 Å under the three conditions, and the combination was prepared. The thickness of the n ⁺ layer is 10
It was set to 00Å.

(2) After that, the source and drain electrodes 6,
After depositing aluminum to be 7 by 3000 Å sputtering method, a photosensitive resist for patterning the source and drain electrodes is applied.

(3) Next, after patterning the photosensitive resist into a desired pattern, the source and drain electrodes are formed by wet etching using the photosensitive resist as a mask.

(4) R using the photosensitive resist as a mask
The n ⁺ layer 5 is etched to an etching depth of 1500Å by IE, and after patterning with a photosensitive resist into a desired pattern, element isolation is performed by RIE.

(5) A protective layer 8 of a silicon nitride film is formed on the surface of the thin film semiconductor formed in (4) by a plasma CVD method, and a desired pattern is further patterned with a photosensitive resist. Then, a probing pad for each electrode is formed. Expose.

(6) Under N ₂ atmosphere, 80 ° C. for 30 minutes, 15
Annealing is performed in steps of 0 ° C. for 30 minutes and 200 ° C. for 120 minutes, and is gradually cooled to room temperature over 12 hours.

As described above, the TFT type optical sensor of the first embodiment of the present invention was manufactured. In order to clarify the effect of the present invention, TFTs having different Lds are formed on the same substrate.
Type photosensor (A) and photoconductive type photosensor without gate electrode (B) having different Lds were prepared, and the effect of the presence or absence of the gate electrode was also confirmed.

FIG. 2 shows the dependence of the photocurrent Ip on d (SiN). Ip increases with the increase of d (SiN), and this is mainly due to two factors.
First, there is an effect that the drain-source electric field is linearized by increasing d (SiN) and moving away the light receiving layer and the current channel layer from the gate electrode. Second, d
When (SiN) is increased, the controllability of the gate electric field with respect to the semiconductor layer is deteriorated, and the Fermi level in the semiconductor at Vgs = 0V is flat band voltage Vf.
This is the effect of approaching b. FIG. 4 shows Vgs-Id characteristics when d (SiN) was changed. From this result, Vgs = 0 at d (SiN) = 3000Å due to the second effect.
V is Vgs = -0.8V at d (SiN) = 6000Å
Is understood to correspond to. Here, in order to estimate the increase in photocurrent due to the first electric field linearization effect, d
V that corresponds to Vgs = 0V at (SiN) = 3000Å
FIG. 3 shows the dependence of the photocurrent Ip on the d (SiN) at the value of gs.
Shown in.

FIG. 5 is a diagram showing the relationship between the film thickness d (i) of the a-Si: H layer and Ip.

When the film thickness d (i) of the a-Si: H layer is changed, the distance between the light receiving layer and the current channel layer from the gate electrode is changed. A second effect of changing the number of generated carriers in the layer and a third effect of changing the magnitude of the influence of the interface surface also appear. In order to eliminate these second and third effects, the d (i) dependence of the gateless sensor manufactured at the same time with the same film structure is evaluated, and the value of the TFT type sensor is divided by each value for correction. The plot is shown in FIG. In the sensor without gate, the electric field between the drain and the source is applied almost linearly, while the second and third effects are equivalent to those of the TFT type, so it is appropriate to estimate the first effect component by this method. is there.

Further, FIG. 7 is a graph in which d (SiN) in FIG. 3 and d (i) in FIG. 6 are replaced with d by using the above-mentioned equations (4) to (7). That is,
The increase in Ip due to the traveling time shortening effect is 3 / d regardless of whether d (SiN) is changed or d (i) is changed.
It is proportional to the square. Here, data of Lds = 10 μm is shown, but the same is true for other Lds tested.

FIG. 8 shows Ip × Lds when Lds is changed.
Is shown. When Lds is changed, the distance for traveling changes, so the vertical axis is Ip × Lds in order to evaluate the linearity of the electric field. As is clear from FIG. 8, the effect of linearization of the electric field when Lds is changed is
It is proportional to the −3/2 power of s. Here, d = 1 μm
However, the same was true for the other d tested. Moreover, it did not depend on what changed d (SiN) and what changed d (i). Further, in the photosensor without a gate electrode, Te / Lds was constant as the Lds increased or decreased. This result supports that the evaluation of Ip × Lds shows the linearity of the electric field.

From the above results, the effect of increasing Ip due to the linearization of the electric field between the drain and the source is 3 / d of d / Lds.
The result is proportional to the square. That is, this means that the linearity of the electric field is due to a device-like function of d / Lds. In the TFT type optical sensor, the idea that such a vertical / horizontal size relationship of the device controls the electric field in the device, and this further controls the traveling property of the carrier of the secondary photocurrent.
It has never been shown before. As a result, conventional Ld
Although s could not be made smaller than this, it is shown that the same effect can be obtained by increasing d.

As an example, Table 1 shows the characteristics of a device in which d (SiN) = 6000 Å compared with the conventional TFT type optical sensor. That is, according to the effect of the present invention, the optical response, S
While maintaining the / N ratio at the same level or higher, a photocurrent of 3 times or more is obtained.

Table 1 is a table showing a characteristic comparison between the conventional TFT type optical sensor and the TFT type optical sensor in which d (SiN) = 6000Å according to the present invention.

In this embodiment, the semiconductor layer is an intrinsic hydrogenated amorphous silicon layer, and the n ⁺ layer is used for the ohmic connection between the semiconductor and the electrode. Although blocking is performed by the n ⁺ layer, the present invention is of course not limited to such an embodiment. Insulating layer composed of silicon oxide layer,
N-type or p-type doped semiconductor layer, C
The same effect can be obtained by using ds, using a p-layer for ohmic connection and using holes as carriers for secondary photocurrent, or using a semiconductor layer or insulating layers composed of a plurality of layers. Needless to say. (Second Embodiment) A second embodiment of the present invention uses a TFT type optical sensor prepared in the process of the first embodiment as a one-dimensional complete contact type sensor array and a drive circuit including TFTs and the like. Configure. FIG. 9 shows an example of a circuit including the TFT type optical sensor of the present invention, TFT, and the like. However, here, the case of a sensor array having nine TFT type photosensors is taken up.

In the figure, TFT type optical sensors E1 to E
The sensor array 9 is composed of 3 blocks, each of which is composed of 3 blocks. Capacitors C1 to C9 and switching transistors T1 to T9 are connected to the TFT type optical sensors E1 to E9, respectively.

The individual electrodes having the same order in the photosensors E1 to E9 are the switching transistors T1 to T, respectively.
9 to one of the common lines 102 to 104. More specifically, the first switching transistors T1, T4, T7 of each block are connected to the common line 102, and the second switching transistors T2, T of each block are connected.
5 and T8 are connected to the common line 103, and the third switching transistors T3, T6 and T9 of each block are connected to the common line 104.
, Respectively. Common lines 102-104
Are connected to the amplifier 105 via the switching transistors T10 to T12, respectively. The gate electrodes of the switching transistors T1 to T9 are commonly connected in each block, and are connected to the parallel output terminal of the shift register 106 in each block. The gate electrodes of the switching transistors T10 to T12 are connected to the parallel output terminal of the shift register 107.

Switching transistors ST1 to ST9
The gate electrodes of the switching transistors T1 to T9.
Similar to the gate electrode of, the block is commonly connected for each block and is connected to the parallel output terminal of the shift register 201 for each block. Therefore, depending on the shift timing of the shift register 201, the switching transistor ST1
~ ST9 is sequentially turned on for each block.

Further, in FIG. 9, common lines 102 to 104 are provided.
Are grounded via capacitors C10 to C12, respectively, and are grounded via switching transistors CT1 to CT3.

The capacities of the capacitors C10 to C12 are set sufficiently larger than those of the capacitors C1 to C9. The gate electrodes of the switching transistors CT1 to CT3 are commonly connected and connected to the terminal 108. That is, when the high level is applied to the terminal 108, the switching transistors CT1 to CT3 are simultaneously turned on and the common lines 102 to 104 are grounded.

Further, the TFT type photosensors E1 to E9 correspond to respective gate electrodes G1 to G9, which are connected to the source electrodes of E1 to E9, respectively, and the gate voltage Vgs = 0V is applied.

FIG. 10 shows a partial plan view of a complete contact sensor made on the basis of the circuit diagram shown in FIG. In the figure, 111 is a matrix-shaped wiring portion including common lines 102 to 104, 112 is a TFT type optical sensor portion according to the present invention, 113 is a charge storage portion including capacitors C1 to C9, and 114 is switching transistors T1 to T9. And a transfer switch using a TFT having the same structure as the TFT type optical sensor of the present invention, 115 is a TF of the present invention including switching transistors T1 to T9.
A discharge switch using a TFT having the same structure as the T-type optical sensor, 116 is a lead line connecting the signal output of the transfer switch 114 to the signal processing IC, and 117 is a capacitor C.
A load capacitor composed of 10 to C12 for accumulating and reading out the signal charges transferred by the transfer switch 114.

FIG. 11 is a sectional view taken along the line AA 'shown in FIG. As is clear from the figure, the TFT type optical sensor unit 11
2, charge storage section 113, transfer switch 114, matrix-shaped wiring section 111, and the like (the same applies to discharge switch 115 and load capacitor 117), metal, insulating layer, photoconductive semiconductor, ohmic contact layer, metal, protection It has the same structure composed of layers. The method of creating the material and the like is the same as in the first embodiment. However, the film thickness of silicon nitride can be changed from the conventional 3000 Å to 600
Changed to 0Å. The film thickness of the a-Si: H layer, which is a semiconductor layer, is 6500Å as in the conventional case.

An example has been shown in which the transfer switch 114 and the discharge switch 115 are formed of TFTs having the same structure as the TFT type optical sensor of the present invention.

As shown in Table 1, d (SiN) is 30
The ON resistance of the TFT is about 2 when changing from 00Å to 6000Å
This is twice the value, and the characteristics as a switch deteriorate. Therefore, in this embodiment, the switch TFT 114,
By setting the W / L of 115 to twice the conventional value,
It has the same switching characteristics as before.

As shown in FIG. 1, a wear resistant layer 11 made of glass or the like is formed on the photoelectric conversion portion and the driving circuit portion, and a light source 12 such as a light emitting diode is formed from the back surface of a transparent substrate such as glass.
It can be used for a lensless complete contact sensor array for illuminating the document and reading the original 13. In addition, the optical sensor array of the present invention has a unity-magnification imaging lens 1 as shown in FIG.
It can also be used for a full contact sensor array using 4.

FIG. 13 is a schematic configuration diagram showing an example of a facsimile having a communication function as an image information processing apparatus configured by using the sensor unit according to this embodiment.

Here, 202 is a feeding roller as a feeding means for feeding the document PP toward the reading position, and 20
Reference numeral 4 is a separating piece for surely separating and feeding the originals PP one by one. A platen roller 206 is provided at a reading position with respect to the sensor unit, regulates the surface to be read of the document 6, and serves as a transport unit that transports the document PP.

In the illustrated example, P is a recording medium in the form of a roll paper, and the image information read by the sensor unit or the image information transmitted from the outside in the case of a facsimile machine or the like is reproduced here. Reference numeral 210 is a recording head as recording means for performing the image formation, and various types such as a thermal head and an inkjet recording head can be used. The recording head may be of a serial type or a line type.
Reference numeral 212 denotes a platen roller as a conveying unit that conveys the recording medium P to the recording position of the recording head 210 and regulates the recording surface thereof.

Reference numeral 220 denotes an operation panel provided with a switch for accepting an operation input as an input / output means, a message, and a display section for notifying the state of the apparatus.

Reference numeral 230 denotes a system control board as a control means, which is provided with a control section (controller) for controlling each section, a drive circuit (driver) for an optical sensor, a processing section (processor) for image information, a transmission / reception section, and the like. To be 240 is the power supply of the device.

Recording means used in the information processing apparatus of the present invention includes, for example, US Pat.
It is preferable that the specification and the principle of 4740796 are disclosed. According to this method, at least one of the electrothermal converters arranged corresponding to the sheet or liquid path holding the liquid (ink) gives a rapid temperature rise corresponding to the recorded information and exceeding the nucleate boiling. By applying a drive signal, heat energy is generated in the electrothermal converter, causing film boiling on the heat-acting surface of the recording head, and as a result, bubbles in the liquid (ink) that correspond one-to-one to this drive signal. Is effective because it can form The growth of this bubble,
The contraction causes the liquid (ink) to be ejected through the ejection opening to form at least one droplet.

Further, as a full line type recording head having a length corresponding to the maximum recording medium width that can be recorded by the recording apparatus, a combination of a plurality of recording heads as disclosed in the above-mentioned specification is used. Either a structure that satisfies the length or a structure as one recording head integrally formed may be used.

In addition, the ink can be attached to the replaceable chip type recording head or the recording head itself, which can be electrically connected to the apparatus main body and can be supplied with ink by being attached to the apparatus main body. The present invention is also effective when a cartridge-type recording head provided integrally with a tank is used.

[0063]

As described in detail above, according to the present invention, the photocurrent can be increased as compared with the conventional TFT type optical sensor, and, for example, a simpler, lower cost, higher speed line sensor is provided. can do.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a TFT type optical sensor according to the present invention.

FIG. 2 is a characteristic diagram showing the dependence of photocurrent on d (SiN).

FIG. 3 is a characteristic diagram showing d (SiN) dependence of photocurrent.

FIG. 4 is a characteristic diagram showing d (SiN) dependence of Vgs-Id characteristics.

FIG. 5 is a characteristic diagram showing d (i) dependence of photocurrent.

FIG. 6 is a characteristic diagram showing d (i) dependence of photocurrent.

FIG. 7 is a characteristic diagram showing d dependence of corrected photocurrent.

FIG. 8 is a characteristic diagram showing the dependency of Ip × Lds on Lds.

FIG. 9 is a circuit diagram showing an example of a complete contact sensor circuit.

FIG. 10 is a partial plan view of a complete contact sensor made based on the circuit shown in FIG.

11 is a cross-sectional view of a complete contact sensor made based on the circuit shown in FIG.

FIG. 12 is a diagram showing an example of a complete contact sensor with a lens according to the present invention.

FIG. 13 is a schematic configuration diagram showing an example of a facsimile having a communication function as an image information processing apparatus configured by using the sensor unit according to the present embodiment.

FIG. 14 Vgs of dark current and photocurrent of TFT type photosensor
It is a characteristic view which shows dependence.

FIG. 15 is a characteristic diagram showing Vgs dependency of γp of a TFT type optical sensor.

FIG. 16 is a diagram showing a distribution of electric field in a device of a TFT type photosensor calculated in a dark state.

FIG. 17 is a characteristic diagram showing d dependence of Lds / Te.

FIG. 18 is a characteristic diagram showing Lds / Te dependency of Lds / Te.

FIG. 19 is a diagram showing the photoresponse of hole generation, recombination, and trap rates throughout the device.

FIG. 20: Vds of dark current and photocurrent of a TFT type photosensor
It is a characteristic view which shows dependence.

[Explanation of symbols]

1 glass substrate, 2 gate electrode, 3 gate insulating film, 4 photoconductive semiconductor film, 5 n ⁺ layer (ohmic contact layer), 6 upper electrode layer, 7 upper electrode layer, 8 protective layer, 11 wear resistant layer, 12 light sources,
13 manuscript, 111 wiring part formed in matrix, 112 optical sensor part, 113 charge storage part, 11
4 Transfer switch, 115 Discharge switch, 1
16 Lead Out Line for Signal Output, 117 Load Capacitor, E1 to E9 Optical Sensor, G1 to G9 First Gate Electrode, C1 to C12 Capacitor, ST1 to ST9
Switching transistor, T1-T12 switching transistor, CT1-CT3 switching transistor, 101 bias power supply, 102 common line, 103 common line, 104 common line, 105
Amplifier, 106 shift register, 107 shift register, 108 terminal, 201 shift register.

Claims (3)

[Claims] 1. A semiconductor layer which functions as a photoelectric conversion layer, a pair of source and drain electrodes electrically connected to the semiconductor layer, and an insulating layer which is disposed with respect to the semiconductor layer. In the photoelectric conversion element having an auxiliary electrode for controlling an electric field, the effective distance between the drain and source electrodes is Lds, and the effective film thickness considering the dielectric constants of the semiconductor layer and the insulating layer is d.
The photoelectric conversion element is characterized in that d / Lds> 1/6. 2. The photoelectric conversion element according to claim 1, wherein
A photoelectric conversion element in which the auxiliary electrode is made of a light-shielding material, and light to be detected enters the semiconductor layer from between the drain and source electrodes. 3. An image reading device comprising a plurality of photoelectric conversion elements according to claim 1 arranged on a light-transmissive insulating substrate to form a one-dimensional line sensor.