Display device and manufacturing method thereof
First Claim
1. A liquid crystal display device comprising a pixel, the pixel comprising:
- a transistor; and
a liquid crystal element electrically connected to the transistor,wherein the transistor comprises;
a gate electrode;
a first insulating layer over the gate electrode;
an oxide semiconductor layer over the first insulating layer;
a source electrode and a drain electrode over the oxide semiconductor layer; and
a second insulating layer over the source electrode and the drain electrode,wherein the transistor has a characteristic that a current flowing between the source electrode and the drain electrode is lower than 10 zA/μ
m at room temperature when a voltage of 3.1 V is applied between the source electrode and the drain electrode, andwherein the current is normalized by a channel width of the transistor.
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Accused Products
Abstract
Disclosed is a display device including a transistor showing extremely low off current. In order to reduce the off current, a semiconductor material whose band gap is greater than that of a silicon semiconductor is used for forming a transistor, and the concentration of an impurity which serves as a carrier donor of the semiconductor material is reduced. Specifically, an oxide semiconductor whose band gap is greater than or equal to 2 eV, preferably greater than or equal to 2.5 eV, more preferably greater than or equal to 3 eV is used for a semiconductor layer of a transistor, and the concentration of an impurity which serves as a carrier donor included is reduced. Consequently, the off current of the transistor per micrometer in channel width can be reduced to lower than 10 zA/μm at room temperature and lower than 100 zA/μm at 85° C.
219 Citations
19 Claims
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1. A liquid crystal display device comprising a pixel, the pixel comprising:
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a transistor; and a liquid crystal element electrically connected to the transistor, wherein the transistor comprises; a gate electrode; a first insulating layer over the gate electrode; an oxide semiconductor layer over the first insulating layer; a source electrode and a drain electrode over the oxide semiconductor layer; and a second insulating layer over the source electrode and the drain electrode, wherein the transistor has a characteristic that a current flowing between the source electrode and the drain electrode is lower than 10 zA/μ
m at room temperature when a voltage of 3.1 V is applied between the source electrode and the drain electrode, andwherein the current is normalized by a channel width of the transistor.
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2. A display device comprising:
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a transistor; and a pixel electrode electrically connected to the transistor, wherein the transistor comprises; a gate electrode; a gate insulating film over the gate electrode; a semiconductor film comprising a channel formation region, over the gate electrode with the gate insulating film therebetween; a source electrode over and electrically connected to the semiconductor film; and a drain electrode over and electrically connected to the semiconductor film; and wherein the transistor has a characteristic that a current flowing between the source electrode and the drain electrode is lower than 10 zA/μ
m at room temperature when a voltage of 3.1 V is applied between the source electrode and the drain electrode,wherein the current is normalized by a channel width of the transistor, wherein the semiconductor film comprises indium, zinc, and oxygen, and wherein an energy gap of the semiconductor film is larger than or equal to 2 eV. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10)
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11. A display device comprising:
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a transistor; and a pixel electrode electrically connected to the transistor, wherein the transistor comprises; a gate electrode; a gate insulating film over the gate electrode; a semiconductor film comprising a channel formation region, over the gate electrode with the gate insulating film therebetween; a source electrode over and electrically connected to the semiconductor film; and a drain electrode over and electrically connected to the semiconductor film; and wherein the transistor has a characteristic that a current flowing between the source electrode and the drain electrode is lower than 10 zA/μ
m at room temperature when a voltage of 3.1 V is applied between the source electrode and the drain electrode,wherein the current is normalized by a channel width of the transistor. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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Specification