Provided are a light-receiving element which has more capability of detecting wavelengths than that of existing silicon light-receiving elements and a unit pixel of an image sensor by using it. The light-receiving element includes: a light-receiving unit which is floated or connected to external voltage and absorbs light; an oxide film which is formed to come in contact with a side of the light-receiving unit; a source and a drain which stand off the light-receiving unit with the oxide film in between and face each other; a channel which is formed between the source and the drain and forms an electric current between the source and the drain; and a wavelength expanding layer which is formed in at least one among the light-receiving unit, the oxide film and the channel and forms a plurality of local energy levels by using strained silicon.

A solid-state imaging device includes a plurality of pixels, each of the plurality of pixels including a photoelectric converter. The photoelectric converter includes a first semiconductor region of a first conductivity type, a second semiconductor region of a second conductivity type provided under the first semiconductor region, and a third semiconductor region of the first conductivity type provided under the second semiconductor region. The second semiconductor region has a first end portion and a second end portion opposing to the first end portion. The third semiconductor region has a first region and a second region overlapping with the second semiconductor region in a plan view, and the first region and the second region are spaced apart from each other from a part of the first end portion to a part of the second end portion.

An energy harvesting imaging sensor includes an array of pixel structures each formed from a semiconductor having a photodiode overlying a photovoltaic diode. The photodiode and photovoltaic diode are implemented as a vertically stacked P+/N.sub.WELL/P.sub.SUB junction. This structure enables simultaneous imaging and energy harvesting by generating charge in the photodiode that is indicative of light impinging on the photodiode and simultaneously generating charge from the light in the photovoltaic diode located underneath the photodiode.

An infrared solid state imaging device includes: a first PN junction diode has a first shortest length that is a shortest length from a first junction surface to a second junction surface; a PN junction diode has a second shortest length that is a shortest length from the second junction surface to a third junction surface, the second shortest length being different from the first shortest length; an insulating film serving as an element isolation region which establishes electrical isolation between a first region of the first PN junction diode and a fourth region of the second PN junction diode, and so on; and a metal wire provided on a second region of the first PN junction diode and a third region of the second PN junction diode, wherein the first PN junction diode and the second PN junction diode are connected in series.

An imaging device according to an embodiment of the present disclosure includes: a first substrate; a second substrate; a through wiring line; and an electrically conducive film. The first substrate includes a photoelectric conversion section and a first transistor in a first semiconductor substrate. The photoelectric conversion section and the first transistor are included in a sensor pixel. The second substrate is stacked on the first substrate and includes a second transistor and an opening in a second semiconductor substrate. The second transistor is included in the sensor pixel. The opening extends through the second semiconductor substrate in a stack direction. The through wiring line extends through the opening. The through wiring line electrically couples the first substrate and the second substrate. The electrically conducive film is provided at least between the second semiconductor substrate and the through wiring line. The electrically conducive film is coupled to a fixed potential.

An imaging device according to an embodiment of the present disclosure includes: a first substrate including a sensor pixel that performs photoelectric conversion; a second substrate including a pixel circuit that outputs a pixel signal on a basis of electric charges outputted from the sensor pixel; and a third substrate including a processing circuit that performs signal processing on the pixel signal. The first substrate, the second substrate, and the third substrate are stacked in this order, and a concentration of electrically-conductive type impurities in a region on side of the first substrate is higher than a concentration of electrically-conductive type impurities in a region on side of the third substrate, in at least one or more semiconductor layers in which a field-effect transistor of the pixel circuit is provided.

Germanium-based sensors are disclosed herein. An exemplary germanium-based sensor includes a germanium photodiode and a junction field effect transistor (JFET) formed from a germanium layer disposed in a silicon substrate, in some embodiments, or on a silicon substrate, in some embodiments. A doped silicon layer, which can be formed by in-situ doping epitaxially grown silicon, is disposed between the germanium layer and the silicon substrate. In embodiments where the germanium layer is on the silicon substrate, the doped silicon layer is disposed between the germanium layer and an oxide layer. The JFET has a doped polysilicon gate, and in some embodiments, a gate diffusion region is disposed in the germanium layer under the doped polysilicon gate. In some embodiments, a pinned photodiode passivation layer is disposed in the germanium layer. In some embodiments, a pair of doped regions in the germanium layer is configured as an e-lens of the germanium-based sensor.

Germanium-based sensors are disclosed herein. An exemplary germanium-based sensor includes a germanium photodiode and a junction field effect transistor (JFET) formed from a germanium layer disposed on and/or in a silicon substrate. A doped silicon layer, which can be formed by in-situ doping epitaxially grown silicon, is disposed between the germanium layer and the silicon substrate. In embodiments where the germanium layer is on the silicon substrate, the doped silicon layer is disposed between the germanium layer and an oxide layer. The JFET has a doped polysilicon gate, and in some embodiments, a gate diffusion region is disposed in the germanium layer under the doped polysilicon gate. In some embodiments, a pinned photodiode passivation layer is disposed in the germanium layer. In some embodiments, a pair of doped regions in the germanium layer is configured as an e-lens of the germanium-based sensor.

A method of fabricating asymmetric vertical field effect transistors (VFETs) includes forming mandrels above a substrate comprising a first semiconductor material. A first set of spacers is formed adjacent to each side of the mandrels, and trenches are formed in portions of the substrate that are not below one of the mandrels or one of the first set of spacers. The method also includes filling the trenches with a second semiconductor material that is different from the first semiconductor material and forming a second set of spacers adjacent to each respective one of the first set of spacers. The second set of spacers is above the second semiconductor material. A plurality of fins is formed such that each one of the plurality of fins includes a portion of the substrate and a portion of the second semiconductor material. Gates are formed between each adjacent pair of fins.

One embodiment provides an imaging apparatus including a photoelectric conversion unit; and a junction type field effect transistor configured to output a signal based on a carrier generated by the photoelectric conversion unit. The junction type field effect transistor includes a semiconductor region of a first conductivity type that forms a channel and a gate region of a second conductivity type. The semiconductor region of the first conductivity type includes a first region and a second region. The first region and the second region are disposed in this order toward a direction to which a carrier in the channel drifts. An impurity density of the second region is lower than an impurity density of the first region.