A light emitting diode includes an n-type structure, a p-type structure, and an active-region sandwiched between the n-type structure and the p-type structure; a p-contact layer formed on the p-type structure; and a p-ohmic contact of a thickness in the range of 0.2-100 nm formed on the p-contact layer, wherein the p-ohmic contact comprises one or more layer of metal oxide.

A photo sensor circuit includes: a photo transistor; a first switching transistor; a second switching transistor; and a capacitance element. The photo transistor includes: a gate connected to a first wiring; a source connected to a second wiring; and a drain. The first switching transistor includes: a gate connected to a third wiring; a source connected to a fourth wiring; and a drain connected to the drain of the photo transistor. The capacitance element includes: a first terminal connected to the drain of the photo transistor; and a second terminal connected to the source of the first switching transistor. The second switching transistor includes: a gate connected to a gate line; a source connected to a signal line; and a drain connected to the first terminal of the capacitance element. The photo transistor, first switching transistor, and second transistor each include an oxide semiconductor layer as a channel layer.

A photoelectric conversion element for detecting the spot size of incident light. The photoelectric conversion element includes a photoelectric conversion substrate having two principal surfaces, and the substrate includes a first sensitivity part and a second sensitivity part that are separated from each other. When a sensitivity area appearing on the principal surface of the first sensitivity part is defined as a first sensitivity area and a sensitivity area appearing on the principal surface of the second sensitivity part is defined as a second sensitivity area, the first sensitivity area receives at least a portion of incident light incident on a light receiving surface, and a pattern is formed such that an increase in an irradiation area of the principal surface irradiated with the incident light reduces the ratio of the first sensitivity area to the second sensitivity area in the irradiation area.

A resonant cavity-enhanced infrared photodetector has an absorber layer disposed between a first transparent layer and a second transparent layer within an optical cavity. The first transparent layer and the second transparent layer have a bandgap which is larger by at least 0.1 eV compared to the absorber layer. Since the bandgaps of the first and second layer are increased relative to the bandgap of the absorber layer, generation of dark current is limited to the absorber layer. The band profiles of the layers had been designed in order to avoid carrier trapping. In one embodiment, the conduction and valence band offsets are configured to allow unimpeded flow of photogenerated charge carriers away from the absorber layer. The photodetector may be a photoconductor, or a photodiode having n-type and p-type layers. In some embodiments, an interface between the absorber layer and a transparent layer is compositionally graded. In other embodiments, one of a conduction band and a valence band of the absorber layer is aligned with an opposite band of a transparent layer so that a photogenerated charge carrier can tunnel from one band of the absorber layer into the opposite band of the transparent layer.

Provided is an organic EL element which has functions of light emitting and photoelectric conversion, reduces heat generated by light emission, has a high ratio of a photoelectric current value and a dark current value. Also provided are a photosensor and a biometric sensor. The organic EL element according to the present invention comprises: a transparent substrate, a transparent electrode, an organic function layer, and opposite electrode. The organic function layer has at least one luminescent layer having a light absorption function. The luminescent layer is composed of a plurality of materials. Among the plurality of materials, an absorptive material having the highest absorbance in a wavelength region of visible and longer wavelength region has a highest energy gap in the luminescent layer. The existing ratio of the absorptive material in the luminescent layer is not more than 50% by volume.

Systems and devices can include a first optical element and a second optical element, the first and second optical elements transparent to visible light; and a photovoltaic element residing between the first optical element and the second optical element, the photovoltaic element transparent to visible light, the photovoltaic element to generate electricity based on the absorption of ultraviolet (UV) and near-infrared (NIR) light. The photovoltaic element can include a conductive element to conduct electricity generated from the absorption of UV and NIR light.

The problem of the present disclosure is to provide a photo sensor circuit that uses oxide semiconductor transistors and the operation of which is stable. The photo sensor circuit includes: a photo transistor; a first switching transistor; a second switching transistor; and a capacitance element. The photo transistor includes: a gate connected to a first wiring; a source connected to a second wiring; and a drain. The first switching transistor includes: a gate connected to a third wiring; a source connected to a fourth wiring; and a drain connected to the drain of the photo transistor. The capacitance element includes: a first terminal connected to the drain of the photo transistor; and a second terminal connected to the source of the first switching transistor. The second switching transistor includes: a gate connected to a gate line; a source connected to a signal line; and a drain connected to the first terminal of the capacitance element. Each of the photo transistor, the first switching transistor, and the second transistor includes an oxide semiconductor layer as a channel layer.

An avalanche photodiode (APD) sensor includes a photoelectric conversion region disposed in a substrate and that converts light incident to a first side of the substrate into electric charge, and a cathode region disposed at a second side of the substrate. The second side is opposite the first side. The APD sensor includes an anode region disposed at the second side of the substrate, a first region of a first conductivity type disposed in the substrate, and a second region of a second conductivity type disposed in the substrate. The second conductivity type is different than the first conductivity type. In a cross-sectional view, the first region and the second region are between the photoelectric conversion region and the second side of the substrate. In the cross-sectional view, an interface between the first region and the second region has an uneven pattern.

A photoelectric conversion element for detecting the spot size of incident light. The photoelectric conversion element includes a photoelectric conversion substrate having two principal surfaces, and the substrate includes a first sensitivity part and a second sensitivity part that are separated from each other. When a sensitivity area appearing on the principal surface of the first sensitivity part is defined as a first sensitivity area and a sensitivity area appearing on the principal surface of the second sensitivity part is defined as a second sensitivity area, the first sensitivity area receives at least a portion of incident light incident on a light receiving surface, and a pattern is formed such that an increase in an irradiation area of the principal surface irradiated with the incident light reduces the ratio of the first sensitivity area to the second sensitivity area in the irradiation area.

A photoelectric conversion element for detecting the spot size of incident light. The photoelectric conversion element includes a photoelectric conversion substrate having two principal surfaces, and comprises a first sensitive part and a second sensitive part that have mutually different photoelectric conversion characteristics. When a sensitive region appearing in the principal surface of the first sensitive part is defined as a first sensitive region, and a sensitive region appearing in the principal surface of the second sensitive part is defined as a second sensitive region, the first sensitive region is configured to receive at least a portion of light incident on a light-receiving surface and to decrease, proportionally to enlargement in an irradiation region of the principal surface irradiated with the incident light, the ratio of the first sensitive region to the second sensitive region in the irradiation region.