Photo detector device having multiple photosensitive transistors

• US 7,935,917 B2
• Filed: 03/18/2009
• Issued: 05/03/2011
• Est. Priority Date: 10/07/2005
• Status: Active Grant

• Current Assignee: GigaDevice Semiconductor Incorporated
• Original Assignee: Integrated Digital Technologies, Inc. (InterDigital, Inc.)
• Inventors: Fann, Sen-Shyong
• Primary Examiner(s): Le; Que T
• Assistant Examiner(s): BUI PHO, PASCAL M
• Application Number:
  US12/406,337
• Publication Number:
  US 20090179243A1
• Time in Patent Office: 776 Days
• Field of Search: 250/208.1, 250/214.1, 250/214.R, 348272-283, 348/294, 348/302, 348/307, 348/308
• US Class Current: 250/208.1
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: H01L 27/14681 Bipolar transistor imagers

Abstract

A photo detector device includes a photosensitive transistor capable of detecting an optical signal including an image component and a background component and converting the optical signal into a current including an image current corresponding to the image component and a background current corresponding to the background component, a first amplifier module electrically connected to the photosensitive transistor capable of canceling the background current and amplifying the image current, and a second amplifier module electrically connected to the first amplifier module capable of detecting a direct-current (dc) portion of the image current.

Claims

1. A photo detector device, comprising:

a substrate;

a common gate electrode over the substrate;

an insulating layer over the common gate electrode and the substrate;

a semiconductor layer over the insulating layer;

a first diffused region and a second diffused region both disposed over the semiconductor layer and the common gate electrode, wherein the common gate electrode is between the first diffused region and the second diffused region;

a third diffused region over the semiconductor layer and the common gate electrode,

wherein the first diffused region, the common gate electrode and the third diffused region form a first photosensitive transistor capable of detecting an optical signal, and the second diffused region, the common gate electrode and the third diffused region form a second photosensitive transistor capable of detecting an optical signal, and

wherein the common gate electrode is a first gate electrode, the device further comprising;

a second gate electrode over the substrate; and

a fourth diffused region over the semiconductor layer and the second gate electrode, wherein the fourth diffused region, the second gate electrode and one of the first diffused region and the second diffused region from a switching transistor capable driving the first and second photosensitive transistors.

2. The device of claim 1, wherein the common gate electrode extends to below at least a portion of at least one of the first diffused region and the second diffused region.

3. The device of claim 1, wherein the common gate electrode is aligned with an edge of at least one of the first diffused region and the second diffused region.

4. A photo detector device, comprising:

a first photosensitive transistor capable of detecting an optical signal, the first photosensitive transistor comprising;

a first diffused region;

a second diffused region; and

a common gate electrode, the first diffused region and the second diffused region being over the common gate electrode; and

a second photosensitive transistor capable of detecting an optical signal, the second photosensitive transistor comprising;

the second diffused region;

a third diffused region; and

the common gate electrode, the third diffused region being over the common gate electrode and the second diffused region being between the first diffused region and the third diffused region, and

a switching transistor capable of driving the first and second photosensitive transistors, the switching transistor comprising;

the first or third diffused region;

a fourth diffused region; and

a switching transistor gate electrode, the fourth diffused region being over the switching transistor gate electrode.

5. The device of claim 4, wherein the common gate electrode extends to below at least a portion of the first diffused region and the third diffused region.

6. The device of claim 4, wherein the common gate electrode is aligned with an edge of at least the first diffused region and the third diffused region.