Transistor including an oxide semiconductor and display device using the same

A semiconductor device comprising:

• a transistor;
• and
• a photodiode over the transistor;
• wherein the transistor comprises:
• a gate electrode;
• a gate insulating layer adjacent to the gate electrode;
• an oxide semiconductor layer adjacent to the gate electrode with the gate insulating layer interposed therebetween;
• and
• a silicon oxide film in contact with the oxide semiconductor layer,
• wherein the gate electrode is electrically connected to a first terminal of the photodiode,
• wherein the oxide semiconductor layer comprises a channel formation region,
• wherein an absolute value of an amount of a variation of a threshold voltage of the transistor due to irradiation of light to at least a part of the oxide semiconductor layer at an intensity of 10 μW/cm2 for 90 seconds is less than or equal to 0.65 V, the light having a wavelength of 350 nm, and
• wherein a carrier density of the oxide semiconductor layer is lower than 1×1014/cm3.

A semiconductor device comprising:

• a transistor;
• and
• a photodiode over the transistor;
• wherein the transistor comprises:
• a gate electrode;
• a gate insulating layer adjacent to the gate electrode;
• an oxide semiconductor layer adjacent to the gate electrode with the gate insulating layer interposed therebetween;
• and
• a silicon oxide film in contact with the oxide semiconductor layer,
• wherein the gate electrode is electrically connected to a first terminal of the photodiode,
• wherein the oxide semiconductor layer comprises a channel formation region,
• wherein an absolute value of an amount of a variation of a gate voltage value of the transistor at drain current of 1×10−10 A due to irradiation of light to at least a part of the oxide semiconductor layer at 1×1013 photons/cm2·sec is less than or equal to 3.0 V, the light having a wavelength greater than or equal to 350 nm, and
• wherein a carrier density of the oxide semiconductor layer is lower than 1×1014/cm3.

A semiconductor device comprising:

• a transistor;
• and
• a photodiode over the transistor;
• wherein the transistor comprises:
• a gate electrode;
• a gate insulating layer adjacent to the gate electrode;
• an oxide semiconductor layer adjacent to the gate electrode with the gate insulating layer interposed therebetween;
• and
• a silicon oxide film in contact with the oxide semiconductor layer,
• wherein the gate electrode is electrically connected to a first terminal of the photodiode,
• wherein the oxide semiconductor layer comprises a channel formation region,
• wherein an absolute value of an amount of a variation of a gate voltage value of the transistor at drain current of 1×10−10 A due to irradiation of light to at least a part of the oxide semiconductor layer at an intensity of 10 μW/cm2 for 90 seconds is less than or equal to 3.0 V, the light having a wavelength greater than or equal to 350 nm, and
• wherein a carrier density of the oxide semiconductor layer is lower than 1×1014/cm3.

A semiconductor device comprising:

• a transistor;
• and
• a photodiode over the transistor;
• wherein the transistor comprises:
• a gate electrode;
• a gate insulating layer adjacent to the gate electrode;
• an oxide semiconductor layer adjacent to the gate electrode with the gate insulating layer interposed therebetween;
• and
• a silicon oxide film in contact with the oxide semiconductor layer,
• wherein the gate electrode is electrically connected to a first terminal of the photodiode,
• wherein the oxide semiconductor layer comprises a channel formation region,
• wherein an absolute value of an amount of a variation of a threshold voltage of the transistor due to an application of a negative gate bias is smaller than an absolute value of an amount of a variation of a threshold voltage of the transistor due to an application of a positive gate bias,
• wherein the application of the positive gate bias and the application of the negative gate bias are preformed at the same electric field strength for the same period, and
• wherein a carrier density of the oxide semiconductor layer is lower than 1×1014/cm3.