Display device and manufacturing method thereof

摘要

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.

主权项

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 terminal and a drain terminal over the oxide semiconductor layer; anda second insulating layer over the source terminal and the drain terminal, wherein the oxide semiconductor layer comprises indium, gallium, and zinc, wherein the oxide semiconductor layer is an intrinsic semiconductor or a substantially intrinsic semiconductor, wherein off current of the transistor is lower than 10 zA/μm at room temperature, wherein the oxide semiconductor layer comprises a composition represented by InMO3(ZnO)m, and wherein M is selected from Ga, Al, Mn, and Co, and m is larger than 0.