Abstract: A positive electrode active material in which the number of defects that cause deterioration is small or progress of the defect is suppressed is provided. The positive electrode active material is used for a secondary battery. The positive electrode active material contains lithium cobalt oxide containing an additive element. After a cycle test is performed on a cell that uses the positive electrode active material for a positive electrode and a lithium electrode as a counter electrode, the positive electrode active material includes a defect and contains at least the same element as the additive element in a region in the vicinity of the defect. The additive element is contained also in a surface portion of the positive electrode active material.

Abstract: A novel method for forming a metal oxide is provided. The metal oxide is formed using a precursor with a high decomposition temperature while a substrate is heated to higher than or equal to 300° C. and lower than or equal to 500° C. In the formation, plasma treatment, microwave treatment, or heat treatment is preferably performed as impurity removal treatment in an atmosphere containing oxygen. The impurity removal treatment may be performed while irradiation with ultraviolet light is performed. The metal oxide is formed by alternate repetition of precursor introduction and oxidizer introduction. For example, the impurity removal treatment is preferably performed every time the precursor introduction is performed more than or equal to 5 times and less than or equal to 10 times.

Abstract: A positive electrode and a secondary battery with little deterioration due to charge and discharge are provided. A positive electrode and a secondary battery with high electrode density are provided. Alternatively, a positive electrode and a secondary battery with excellent rate characteristics are provided. The positive electrode contains a positive electrode active material and a coating material. The coating material covers at least part of a surface of the positive electrode active material, and the positive electrode active material contains lithium cobalt oxide containing magnesium, fluorine, aluminum, and nickel. The lithium cobalt oxide includes a region with the highest concentration of one or more selected from the magnesium, the fluorine, and the aluminum in a surface portion. The coating material is preferably one or more selected from glass, carbon black, graphene, and a graphene compound.

Abstract: A semiconductor device that enables lower power consumption and data storage imitating a human brain is provided. The semiconductor device includes a control unit, a memory unit, and a sensor unit. The memory unit includes a memory circuit and a switching circuit. The memory circuit includes a first transistor and a capacitor. The switching circuit includes a second transistor and a third transistor. The first transistor and the second transistor include a semiconductor layer including a channel formation region with an oxide semiconductor, and a back gate electrode. The control unit has a function of switching a signal supplied to the back gate electrode, in accordance with a signal obtained at the sensor unit.

Abstract: It is an object to provide a semiconductor device with less power consumption as a semiconductor device including a thin film transistor using an oxide semiconductor layer. It is an object to provide a semiconductor device with high reliability as a semiconductor device including a thin film transistor using an oxide semiconductor layer. In the semiconductor device, a gate electrode layer (a gate wiring layer) intersects with a wiring layer which is electrically connected to a source electrode layer or a drain electrode layer with an insulating layer which covers the oxide semiconductor layer of the thin film transistor and a gate insulating layer interposed therebetween. Accordingly, the parasitic capacitance formed by a stacked-layer structure of the gate electrode layer, the gate insulating layer, and the source or drain electrode layer can be reduced, so that low power consumption of the semiconductor device can be realized.

Abstract: A novel, highly convenient or reliable functional panel is provided. A novel, highly convenient or reliable method for manufacturing a functional panel is provided. The functional panel includes a first base; a second base having a region overlapping with the first base; a bonding layer that bonds the first base to the second base; and an insulating layer in contact with the first base, the second base, and the bonding layer. With this structure, an opening which is formed easily in a region where the bonding layer is in contact with the first base or the second base can be filled with the insulating layer, which can prevent impurities from being diffused into the functional layer located in a region surrounded by the first base, the second base, and the bonding layer that bonds the first base to the second base.

Abstract: A method of manufacturing, with high mass productivity, liquid crystal display devices having highly reliable thin film transistors with excellent electric characteristics is provided. In a liquid crystal display device having an inverted staggered thin film transistor, the inverted staggered thin film transistor is formed as follows: a gate insulating film is formed over a gate electrode; a microcrystalline semiconductor film which functions as a channel formation region is formed over the gate insulating film; a buffer layer is formed over the microcrystalline semiconductor film; a pair of source and drain regions are formed over the buffer layer; and a pair of source and drain electrodes are formed in contact with the source and drain regions so as to expose a part of the source and drain regions.

Abstract: A novel display apparatus is provided. The display apparatus includes a display portion and a peripheral circuit for driving the display portion, and the display portion is provided to overlap with and above the peripheral circuit. The display portion include a plurality of pixels arranged in a matrix, and the plurality of pixels each have a function of emitting light. The peripheral circuit includes a first transistor, and the pixel includes a second transistor. A semiconductor layer included in the first transistor and a semiconductor layer included in the second transistor are formed using materials having different compositions.

Abstract: A display device having a photosensing function is provided. A display device having a biometric authentication function typified by fingerprint authentication is provided. A display device having a touch panel function and a biometric authentication function is provided. The display device includes a first substrate, a light guide plate, a first light-emitting element, a second light-emitting element, and a light-receiving element. The first substrate and the light guide plate are provided to face each other. The first light-emitting element and the light-receiving element are provided between the first substrate and the light guide plate. The first light-emitting element has a function of emitting first light through the light guide plate. The second light-emitting element has a function of emitting second light to a side surface of the light guide plate.

Abstract: A semiconductor device having favorable electrical characteristics is provided. A first oxide is formed over a substrate; a first insulator is formed over the first oxide; an opening reaching the first oxide is formed in the first insulator; a first oxide film is deposited in contact with the first oxide and the first insulator in the opening; a first insulating film is deposited over the first oxide film; microwave treatment is performed from above the first insulating film; heat treatment is performed on one or both of the first insulating film and the first oxide; a first conductive film is deposited over the first insulating film; and part of the first oxide film, part of the first insulating film, and part of the first conductive film are removed until a top surface of the first insulator is exposed, so that a second oxide, a second insulator, and a first conductor are formed.

Abstract: A secondary battery stable in a high-potential state and/or a high-temperature state is provided. The secondary battery includes a positive electrode and a negative electrode, and one or both of the positive electrode and the negative electrode contain an active material and a composite compound with a crystal structure. The composite compound has a function of a binder. The composite compound can also be used as an electrolyte. The composite compound with a crystal structure has typically a molecular crystal. The composite compound with a crystal structure can be obtained by mixing a first compound and a second compound while heating is performed at higher than or equal to a temperature at which a mixture of the first compound and the second compound is melted.

Abstract: A novel display is provided. A display having a small change in chromaticity of a micro light-emitting diode in proportion to current density is provided. A display capable of reducing power consumption in the driver circuit when displaying a still image is provided. The display includes a plurality of pixels each including a display element and a microcontroller. The microcontroller includes a first transistor, a triangular wave generator circuit, a comparator, a switch, and a constant current circuit. The first transistor has a function of retaining a potential corresponding to data written to the pixel by being switched off. The triangular wave generator circuit has a function of generating a triangular wave signal. The comparator has a function of generating an output signal corresponding to the potential and the triangular wave signal.

Abstract: A transistor which is resistant to a short-channel effect is provided. The transistor includes a first conductor in a ring shape, an oxide semiconductor including a region extending through an inside of a ring of the first conductor, a first insulator between the first conductor and the oxide semiconductor, a second insulator between the first conductor and the first insulator, and a charge trap layer inside the ring of the first conductor. The charge trap layer is inside the second insulator and configured to be in a floating state.

Abstract: A novel method for fabricating a display apparatus is provided. An anode is formed over an insulating layer, an EL layer is formed over the anode, and a cathode is formed over the EL layer. A plurality of light-emitting elements are formed without provision of a partition by selectively removing parts of the anode, the EL layer, and the cathode. A conductive layer having a light-transmitting property is formed to cover the plurality of light-emitting elements. The cathodes of the plurality of light-emitting elements are electrically connected to the conductive layer.

Abstract: A convenient electronic device or the like is provided. The power consumption of an electronic device or the like is reduced. An electronic device or the like having high visibility regardless of the brightness of external light is provided. An electronic device or the like that can display both a smooth moving image and an eye-friendly still image is provided. Such an electronic device is an electronic device including a first display portion, a second display portion, and a control portion. The control portion is configured to make the first display portion and the second display portion individually display two or more of a first image, a second image, and a third image at a time. The first image is displayed with reflected light, the second image is displayed with emitted light, and the third image is displayed with light including both reflected light and emitted light.

Abstract: Provided is a method for manufacturing a semiconductor device whose electric characteristics are prevented from being varied and whose reliability is improved. In the method, an insulating film is formed over an oxide semiconductor film, a buffer film is formed over the insulating film, oxygen is added to the buffer film and the insulating film, a conductive film is formed over the buffer film to which oxygen is added, and an impurity element is added to the oxide semiconductor film using the conductive film as a mask. An insulating film containing hydrogen and overlapping with the oxide semiconductor film may be formed after the impurity element is added to the oxide semiconductor film.

Abstract: A display device with excellent visibility can be provided. The display device includes a display region displayed by a light-emitting element. In the display region, a point touched by a user is a first point, a point which has been touched by the user prior to the first point is a second point, a vector that starts at the first point and ends at the second point is a first vector, a vector obtained by multiplying the first vector by k (k is a real number) is a second vector, and a point that is the second vector away from the first point is a third point, the display region includes a first region and a second region obtained by excluding the first region from the display region. The first region includes a first circle and a second circle, the center of the first circle is the first point, and the center of the second circle is the third point. The luminance in the first region is higher than the luminance in the second region.

Abstract: A semiconductor device with a novel structure is provided. The semiconductor device includes a plurality of memory cells each including a transistor and a capacitor, and capacitors included in adjacent memory cells are provided to overlap with each other. A first capacitor included in a first memory cell is provided so as to partly overlap with a second memory cell adjacent to the first memory cell. A second capacitor included in a second memory cell and the first capacitor are provided over different layers. The second capacitor is provided so as to partly overlap with the first memory cell. The first capacitor and the second capacitor include a region where they overlap with each other. The first and second capacitors include a ferroelectric. The ferroelectric preferably includes hafnium, zirconium, or at least one element selected from Group III-V elements. The transistor preferably includes an oxide semiconductor in a semiconductor layer where a channel is formed.

Abstract: The semiconductor device includes a driver circuit portion including a driver circuit and a pixel portion including a pixel. The pixel includes a gate electrode layer having a light-transmitting property, a gate insulating layer, a source electrode layer and a drain electrode layer each having a light-transmitting property provided over the gate insulating layer, an oxide semiconductor layer covering top surfaces and side surfaces of the source electrode layer and the drain electrode layer and provided over the gate electrode layer with the gate insulating layer therebetween, a conductive layer provided over part of the oxide semiconductor layer and having a lower resistance than the source electrode layer and the drain electrode layer, and an oxide insulating layer in contact with part of the oxide semiconductor layer.

Abstract: An anomaly detection system that outputs an anomaly detection signal before a safety valve of a secondary battery is opened is provided. The anomaly detection system includes a strain sensor, a memory, and a comparator. The memory has a function of retaining an analog potential, and the comparator has a function of comparing a potential output by the strain sensor and the analog potential retained by the memory. The strain sensor is attached to the secondary battery before use, and a predetermined potential is retained in the memory. When a housing of the secondary battery expands while the secondary battery is used, and the potential output by the strain sensor becomes higher (or lower) than the predetermined potential, an anomaly detection signal is output.