314results about How to "Stable electrical characteristics" patented technology

An object is to provide a semiconductor device having stable electric characteristics in which an oxide semiconductor is used. An oxide semiconductor layer is subjected to heat treatment for dehydration or dehydrogenation treatment in a nitrogen gas or an inert gas atmosphere such as a rare gas (e.g., argon or helium) or under reduced pressure and to a cooling step for treatment for supplying oxygen in an atmosphere of oxygen, an atmosphere of oxygen and nitrogen, or the air (having a dew point of preferably lower than or equal to −40° C., still preferably lower than or equal to −50° C.) atmosphere. The oxide semiconductor layer is thus highly purified, whereby an i-type oxide semiconductor layer is formed. A semiconductor device including a thin film transistor having the oxide semiconductor layer is manufactured.

An oxide semiconductor stacked film which does not easily cause a variation in electrical characteristics of a transistor and has high stability is provided. Further, a transistor which includes the oxide semiconductor stacked film in its channel formation region and has stable electrical characteristics is provided. An oxide semiconductor stacked film includes a first oxide semiconductor layer, a second oxide semiconductor layer, and a third oxide semiconductor layer which are sequentially stacked and each of which contains indium, gallium, and zinc. The content percentage of indium in the second oxide semiconductor layer is higher than that in the first oxide semiconductor layer and the third oxide semiconductor layer, and the absorption coefficient of the oxide semiconductor stacked film, which is measured by the CPM, is lower than or equal to 3×10−3 / cm in an energy range of 1.5 eV to 2.3 eV.

Oxide layers which contain at least one metal element that is the same as that contained in an oxide semiconductor layer including a channel are formed in contact with the top surface and the bottom surface of the oxide semiconductor layer, whereby an interface state is not likely to be generated at each of an upper interface and a lower interface of the oxide semiconductor layer. Further, it is preferable that an oxide layer, which is formed using a material and a method similar to those of the oxide layers be formed over the oxide layers Accordingly, the interface state hardly influences the movement of electrons.

An object is to provide a semiconductor device including an oxide semiconductor, which has stable electrical characteristics and improved reliability. In a transistor including an oxide semiconductor film, insulating films each including a material containing a Group 13 element and oxygen are formed in contact with the oxide semiconductor film, whereby the interfaces with the oxide semiconductor film can be kept in a favorable state. Further, the insulating films each include a region where the proportion of oxygen is higher than that in the stoichiometric composition, so that oxygen is supplied to the oxide semiconductor film; thus, oxygen defects in the oxide semiconductor film can be reduced. Furthermore, the insulating films in contact with the oxide semiconductor film each have a stacked structure so that films each containing aluminum are provided over and under the oxide semiconductor film, whereby entry of water into the oxide semiconductor film can be prevented.

A semiconductor light emitting device can have stable electric characteristics and can emit light with high intensity from a substrate surface. The device can include a transparent substrate and a semiconductor layer on the substrate. The semiconductor layer can include a first conductive type semiconductor layer, a luminescent layer, a second conductive type semiconductor layer, and first and second electrodes disposed to make contact with the first and second conductive type semiconductor layers, respectively. The first conductive type semiconductor layer, the luminescent layer, and the second conductive type semiconductor layer can be laminated in order from the side adjacent the substrate. An end face of the semiconductor layer can include a first terrace provided in an end face of the first conductive type semiconductor layer in parallel with the substrate surface, and an inclined end face region provided nearer to the substrate than the first terrace. The first electrode disposed in the inclined end face region can reflect light emitted from the luminescent layer to the substrate.

A highly reliable semiconductor device exhibiting stable electrical characteristics is provided. Further, a highly reliable semiconductor device is provided. Oxide semiconductor films are stacked so that the conduction band has a well-shaped structure. A second oxide semiconductor film having a crystalline structure is provided over the first oxide semiconductor film and a third oxide semiconductor film is provided over the second oxide semiconductor film. The bottom of a conduction band in the second oxide semiconductor film is deeper from a vacuum level than the bottom of a conduction band in the first oxide semiconductor film and the bottom of a conduction band in the third oxide semiconductor film.