SEMICONDUCTOR DEVICE

• US 20110227082A1
• Filed: 03/15/2011
• Published: 09/22/2011
• Est. Priority Date: 03/19/2010
• Status: Abandoned Application

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Inoue, Takayuki, Kikuchi, Erumu, Godo, Hiromichi, Sakata, Junichiro, Yamazaki, Shunpei, Hiraishi, Suzunosuke, Tsubuku, Masashi, Miyanaga, Akiharu
• Application Number:
  US13/048,023
• Publication Number:
  US 20110227082A1
• Time in Patent Office: Days
• US Class Current: 257/59
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 29/24 including, apart from doping materials or other impurities, only semiconductor materials not provided for in groups H01L29/16, H01L29/18, H01L29/20, H01L29/22 including organic materials H10K99/00
• CPC Class Codes: H01L 29/41733 for thin film transistors with insulated gate
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H01L 31/032 including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312
• CPC Class Codes: H01L 31/18 Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof

Abstract

An oxide semiconductor layer in which “safe” traps exist exhibits two kinds of modes in photoresponse characteristics. By using the oxide semiconductor layer, a transistor in which light deterioration is suppressed to the minimum and the electric characteristics are stable can be achieved. The oxide semiconductor layer exhibiting two kinds of modes in photoresponse characteristics has a photoelectric current value of 1 pA to 10 nA inclusive. When the average time τ₁ until which carriers are captured by the “safe” traps is large enough, there are two kinds of modes in photoresponse characteristics, that is, a region where the current value falls rapidly and a region where the current value falls gradually, in the result of a change in photoelectric current over time.

Claims

1. A semiconductor device, comprising:

an oxide semiconductor layer at least a part of which overlaps with a gate electrode with a gate insulating layer provided therebetween,

wherein the oxide semiconductor layer has a channel formation region, and

wherein photoresponse characteristics of the channel formation region of the oxide semiconductor layer have two kinds of modes after light irradiation is performed and a light source is turned off.

2. The semiconductor device according to claim 1, wherein the oxide semiconductor layer has a photoelectric current value of greater than or equal to 1 pA and less than or equal to 10 nA.

3. The semiconductor device according to claim 1, wherein the oxide semiconductor layer comprises at least one of In, Zn, and Ga.

4. The semiconductor device according to claim 1, wherein a photoelectric current value of the oxide semiconductor layer after 100 seconds of light irradiation is greater than or equal to 400 aA/μ

m and less than or equal to 0.1 pA/μ

m.

5. The semiconductor device according to claim 1, wherein the two kinds of modes comprise a region where a photoelectric current value of the oxide semiconductor layer falls rapidly and a region where the photoelectric current value falls gradually, in a result of a change in photoelectric current over time.

6. A semiconductor device comprising:

a pixel porting including a transistor,

wherein a channel formation region of the transistor is formed in an oxide semiconductor layer whose photoresponse characteristics have two kinds of modes after light irradiation is performed and a light source is turned off.

7. The semiconductor device according to claim 6, wherein the oxide semiconductor layer has a photoelectric current value of greater than or equal to 1 pA and less than of equal to 10 nA.

8. The semiconductor device according to claim 6, wherein the oxide semiconductor layer comprises at least one of In, Zn, and Ga.

9. The semiconductor device according to claim 6, wherein a photoelectric current value of the oxide semiconductor layer after 100 seconds of light irradiation is greater than or equal to 400 aA/μ

m and less than or equal to 0.1 pA/μ

m.

10. The semiconductor device according to claim 6, wherein the two kinds of modes comprise a region where a photoelectric current value of the oxide semiconductor layer falls rapidly and a region where the photoelectric current value falls gradually, in a result of a change in photoelectric current over time.

11. A semiconductor device, comprising:

an oxide semiconductor layer at least a part of which overlaps with a gate electrode with a gate insulating layer provided therebetween,

wherein the oxide semiconductor layer has a channel formation region, and

wherein photoresponse characteristics of the channel formation region of the oxide semiconductor layer have at least a first mode and a second mode after light irradiation is performed and a light source is turned off.

12. The semiconductor device according to claim 11, wherein the first mode is a region where a photoelectric current value of the oxide semiconductor layer falls rapidly and the second mode is a region where the photoelectric current value of the oxide semiconductor layer falls gradually, in a result of a change in photoelectric current over time.