Completely integrated contact-type linear image sensor

Morozumi, Shinji; Kurihara, Hajime; Takeshita, T.; Oka, Hideaki; Hasegawa, Kunihiro

doi:10.1109/t-ed.1985.22162

Cited by 34 publications

(3 citation statements)

References 8 publications

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“…Thus, both the a-Si photodiodes and LTPS TFTs can be made on the same array substrate. Similarly combined poly-Si-TFT-a-Si-photosensor structure has been used previously for image sensors applications [8], but in the current approach, we have used the ITO optical window layer as also a Schottky contact to a-Si. Discussion of I-V characteristics of ITO-a-Si contact can be found in our earlier publication [9].…”

Section: A-si Photodiode Structure and Characteristicmentioning

confidence: 99%

Integrated Ambient Light Sensor with an LTPS Noise-Robust Circuit and a-Si Photodiodes for AMLCDs

Matsuki

Hashimoto

Sano

et al. 2010

IEICE Trans. Electron.

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Ambient light sensors have been used to reduce power consumption of Active Matrix Liquid Crystal Displays (AMLCD) adjusting display brightness depending on ambient illumination. Discrete sensors have been commonly used for this purpose. They make module design complex. Therefore it has been required to integrate the sensors on the display panels for solving the issue. So far, many kinds of integrated sensors have been developed using Amorphous Silicon (a-Si) technology or Low Temperature Polycrystalline Silicon (LTPS) technology. These conventional integrated sensors have two problems. One is that LTPS sensors have less dynamic range due to the less photosensitivity of LTPS photodiodes. The other is that both the LTPS and a-Si sensors are susceptible to display driving noises. In this paper, we introduce a novel integrated sensor using both LTPS and a-Si technologies, which can solve these problems. It consists of vertical a-Si Schottky photodiodes and an LTPS differential converter circuit. The a-Si photodiodes have much higher photosensitivity than LTPS ones, and this contributes to wide dynamic range and high accuracy. The LTPS differential converter circuit converts photocurrent of the photodiodes to a robust digital signal. In addition it has a function of canceling the influences of the display driving noises. With the circuit, the sensor can stably and accurately work even under the noises. The performance of the sensor introduced in this paper was measured to verify the advantages of the novel design. The measurement result showed that it worked in a wide ambient illuminance range of 5-55,000 lux with small errors of below 5%. It was also verified that it stably and accurately worked even under the display driving noise. Thus the sensor introduced in this paper achieved the wide dynamic range and noise robustness.

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Section: A-si Photodiode Structure and Characteristicmentioning

confidence: 99%

Integrated Ambient Light Sensor with an LTPS Noise-Robust Circuit and a-Si Photodiodes for AMLCDs

Matsuki

Hashimoto

Sano

et al. 2010

IEICE Trans. Electron.

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“…The optimum coordination number to get the minimum freeenergy of the ideal random network system has been theoretically calculated to be < 2.4. [29] Because of this there are inherent structural defects such as dangling bonds and voids which act as trapping and recombination centers for electrons and holes.…”

Section: Basic Propertiesmentioning

confidence: 99%

Signal and noise analysis of a-Si:H radiation detector-amplifier system

Cho

1992

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Hydrogenated amorphous silicon (a-Si:H) has potential advantages in m',tking radiation detectors for many applications because of its deposition capability on a large-area substrate and its high radiation resistance. Position-sensitive radiation detectors can be made out of a 1-d strip or a 2-d pixel array of a-Si:H pin diodes. In addition, signal processing electronics can be made by thin..film transistors (amorphous silicon or polysilicon "ITTs) on the same substrate. The calculated radiation signal, based on a simple charge collection model agreed well with results from various wave-length light sources and I MeV beta particles on sample diodes. The total noise of the detection system was analyzed into (a) shot noise and (b) 1/f noise from a detector diode, and (c) thermal noise and (d) 1/f noise from the frontend TFr of a charge-sensitive preamplifier. The effective noise charge calculated by convoluting these noise power spectra with the transfer function of a CR-RC shaping amplifier showed a good agreement with the direct measurements of noise charge. The , derived equations of signal and noise charge can be,used to design an a-Si:H pixel detectoramplifier system optimally.Signals from a pixeI can be readout using switching TFTs, or diodes. Prototype tests of a double-diode readout scheme showed that the storage time and the readout time are limited by the resistances of the reverse-biased pixel diode and the tbrward-biased switching diodes respectively. A prototype charge-sensitive amplifier was made using 1 poly-Si TFTs to test the feasibility of making pixel-level amplifiers which would be required in small-signal detection. The measured overall gain-bandwidth product 'was -400MHz and the noise charge was~10,00 electrons at a 1 p.sec shaping time. When the amplifier is connected to a pixel detector of capacitance 0.2 pF, it would give a charge-tovoltage gain of~0.02 mV/electron with a pulse rise time less than 1O0 nsec and a dynamic range of 48 dB.

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“…Polycrystalline silicon (poly-Si) thin film transistors (TFT's) are widely used in various applications, such as three dimensional integrated circuits [I], or image sensors [2]. Especially, there has been great interest in applying poly-Si TFT's to active matrix liquid crystal displays (AMLCD's) because they provide a much higher carrier mobility than amorphous silicon (a-Si) TFT's [3].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of On/Off Current Ratio of Poly-Silicon TFT by Selective Laser-Induced Crystallization of Active Layer

et al. 1997

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We have proposed the new poly-Si TFT which reduces the leakage current effectively by employing highly resistive a-Si region in the channel. The active layer of proposed device is crystallized selectively by employing excimer laser annealing while the both sides of channel near the source/drain are not recrystallized and remained as a-Si. Unlikely LDD or offset structure, the a-Si region which is designed to reduce the leakage current acts as the conduction channel of carriers under the ON state, so that the ON current is decreased very little. The selectively crystallized active layer can be fabricated by irradiating the excimer laser through ITO film of which transmittance at the wave length of laser is selectively adjusted. In the course of fabricating the proposed device, any additional photo masking step is not necessary and misalign problem is eliminated. The experimental results show that the ON/OFF current ratio of proposed poly-Si TFT is 106 while that of conventional one is 105.

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Completely integrated contact-type linear image sensor

Cited by 34 publications

References 8 publications

Integrated Ambient Light Sensor with an LTPS Noise-Robust Circuit and a-Si Photodiodes for AMLCDs

Integrated Ambient Light Sensor with an LTPS Noise-Robust Circuit and a-Si Photodiodes for AMLCDs

Signal and noise analysis of a-Si:H radiation detector-amplifier system

Enhancement of On/Off Current Ratio of Poly-Silicon TFT by Selective Laser-Induced Crystallization of Active Layer

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