Display device having photosensor and method of fabricating the same
First Claim
1. A display device comprising:
- a display portion comprising a plurality of pixels, each of the pixels comprising a first thin film transistor comprising a first semiconductor layer, and a photosensor comprising a second thin film transistor comprising a second semiconductor layer, wherein a grain size of crystals forming the second semiconductor layer is larger than a grain size of crystals forming the first semiconductor layer.
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Accused Products
Abstract
When a photosensor was conventionally provided in a display device, separate modules manufactured in separate steps were installed in the same case. However, decreases in the number of parts and in cost could not be achieved, and a compact size and thinning of the display device was not proceeded. A photosensor is realized by a TFT provided on an insulating substrate. Photocurrent caused by incidence of external light onto a TFT when the TFT is turned-off is detected so that the TFT is used as a photosensor. By performing laser-annealing for a semiconductor layer of the photosensor, an average grain size of crystal particles of the semiconductor layer of the photosensor is made larger than those of a crystal particle of a display portion and a light emission element, thereby improving crystal properties. Thus, a generation efficiency of the photocurrent of the photosensor can be increased.
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Citations
15 Claims
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1. A display device comprising:
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a display portion comprising a plurality of pixels, each of the pixels comprising a first thin film transistor comprising a first semiconductor layer, and a photosensor comprising a second thin film transistor comprising a second semiconductor layer, wherein a grain size of crystals forming the second semiconductor layer is larger than a grain size of crystals forming the first semiconductor layer. - View Dependent Claims (3, 4, 5)
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2. A display device comprising:
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a display portion comprising a plurality of pixels, each of the pixels comprising a first thin film transistor comprising a first semiconductor layer, and a photosensor comprising a second thin film transistor comprising a second semiconductor layer, wherein a crystal length in a predetermined direction of crystals forming the second semiconductor layer is longer than a crystal length in the predetermined direction of crystals forming the first semiconductor layer. - View Dependent Claims (6)
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7. A method of fabricating a display device, comprising:
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forming an amorphous semiconductor layer on an insulating substrate;
crystallizing the amorphous semiconductor layer so as to form a first semiconductor layer of a first grain size and a second semiconductor layer of a second grain size that is larger than the first grain size;
forming a first thin film transistor comprising the first semiconductor layer;
forming a photosensor comprising a second thin film transistor comprising the second semiconductor layer; and
forming a pixel comprising the first thin film transistor in a display portion of the display device. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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8. A method of fabricating a display device, comprising:
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forming an amorphous semiconductor layer on an insulating substrate;
crystallizing the amorphous semiconductor layer so as to form a first semiconductor layer comprising crystals having a first crystal length in a predetermined direction and a second semiconductor layer comprising crystals having a second crystal length in the predetermined direction which is longer than the fist crystal length;
forming a first thin film transistor comprising the first semiconductor layer;
forming a photosensor comprising a second thin film transistor comprising the second semiconductor layer so that an electric conduction of the second thin film transistor is in the predetermined direction; and
forming a pixel comprising the first thin film transistor in a display portion of the display device.
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Specification