# US 8,541,811 B2 · TFT with improved light sensing and TFT substrate using the same and liquid crystal display

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- Number: US 8,541,811 B2
- Document ID: US8541811B2
- Status: Granted
- Kind: B2
- Application number: 12/891,598
- Filed: 2010-09-27
- Published: 2011-01-20
- Granted: 2013-09-24
- Earliest claimed: 2005-07-14
- Assignees: Samsung Display Co., Ltd.
- Applicants: Kwan-Wook Jung; Ung-Sik Kim; Pil-Mo Choi; Seock-Cheon Song; Ho-Suk Maeng; Sang-Hoon Lee; Keun-Woo Park
- Inventors: Kwan-Wook Jung; Ung-Sik Kim; Pil-Mo Choi; Seock-Cheon Song; Ho-Suk Maeng; Sang-Hoon Lee; Keun-Woo Park
- Web page: https://patentgrep.com/patent/US8541811B2

## CPC

- H10D 86/60: wherein the TFTs are in active matrices
- G02F 1/13318: {Circuits comprising a photodetector}
- H10D 30/6715: {characterised by the doping profiles, e.g. having lightly-doped source or drain extensions}
- H10D 30/673: {characterised by the shapes, relative sizes or dispositions of the gate electrodes}
- H10D 86/40: characterised by multiple TFTs
- H10D 86/441: {Interconnections, e.g. scanning lines}
- G02F 1/133308: {Support structures for LCD panels, e.g. frames or bezels}
- G02F 1/13332: {Front frames}
- G02F 2201/58: Arrangements comprising a monitoring photodetector
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS

## Abstract

There are provided a TFT, a TFT substrate using the TFT, a method of fabricating the TFT substrate, and an LCD. The TFT includes a source region, a drain region, and a gate electrode having an opening. The opening of the gate electrode is to enhance the light sensing ability of the TFT when it is used as a light sensor, since light is incident into a region where the opening is formed. The TFT including the gate having the opening can be used in a substrate of a flat display or an LCD using such a substrate. The above TFT can sense light incident from outside the display to adjust the brightness of the screen according to the external illumination.

## Claims

### Claim 1

A display comprising:
a light sensor comprising:
a source region;
a drain region;
an intermediate region positioned between the source region and the drain region,
a gate electrode associated with the source region and the drain region, the gate electrode including one or more openings over the intermediate region, wherein light incident from outside the display passes through the one or more openings and into the intermediate region, and the intermediate region is formed of a material that generates current upon receiving light incident from outside the display; and
at least one pixel transistor, the at least one pixel transistor including an associated source region, an associated drain region, and an associated gate electrode, wherein the associated gate electrode does not include one or more openings; and
wherein the display further comprises a chassis that covers the light sensor and has a light-transmitting part, and the light incident from outside the display passes through the light-transmitting part and the one or more openings into the intermediate region; and
wherein the gate electrode is formed in a closed loop shape to surround the one or more openings in a plan view.

### Claim 2 (depends on 1)

The display of claim 1, wherein the display further comprises a back light to generate light, and wherein the light sensor is substantially shielded from the back light.

### Claim 3 (depends on 2)

The display of claim 2, wherein the current generated from the light sensor controls an amount of light generated from the back light.

### Claim 4 (depends on 2)

The display of claim 2, wherein the light-transmitting part is a perforation hole.

### Claim 5 (depends on 1)

The display of claim 1, wherein the display comprises a liquid crystal display.

### Claim 6 (depends on 1)

The display of claim 1, wherein the display comprises an organic light emitting diode display.

### Claim 7 (depends on 1)

The display of claim 1, wherein the source region includes a first concentration of impurities type,
wherein the intermediate region comprises a lightly doped region including a second concentration of impurities of the first impurity type,
wherein the lightly doped region includes a first portion formed adjacent to the source region and a second portion formed adjacent to the drain region, and
wherein the gate electrode partially covers at least one of the first portion and the second portion in a plan view.