A phototransistor device to act as an artificial photonic synapse includes a substrate and a graphene source-drain channel patterned on the substrate. A perovskite quantum dot layer is formed on the graphene source-drain channel. The perovskite quantum dot layer is methylammonium lead bromide material. A method of operating the phototransistor device as an artificial photonic synapse includes applying a first fixed voltage to a gate of the phototransistor and a second fixed voltage across the graphene source-drain channel. A presynaptic signal is applied as stimuli across the graphene source-drain channel. The presynaptic signal includes one or more pulses of light or electrical voltage. A current across the graphene source-drain channel is measured to represent a postsynaptic signal.

A solar cell of an embodiment includes a p-electrode, an n-electrode, a p-type light-absorbing layer located between the p-electrode and the n-electrode and mainly containing a cuprous oxide, and an n-type layer that includes a first n-type layer which is located between the p-type light-absorbing layer and the n-electrode, which mainly contains a compound represented by Ga.sub.v1Zn.sub.v2Sn.sub.v3M1.sub.v4O.sub.v5, the M1 being one or more selected from the group consisting of Hf, Zr, In, Ti, Al, B, Mg, Si, and Ge, the v1, the v2, and the v4 being numerical values of 0.00 or more, the v3 and the v5 being numerical values of more than 0, at least one of the v1 and the v2 being a numerical value of more than 0, and the v5 when a sum of the v1, the v2, the v3, and the v4 is 1 being 1.00 or more and 2.00 or less, and which is located on the n-electrode side, and a second n-type layer which is a layer that mainly contains a compound represented by Ga.sub.w1M2.sub.w2M3.sub.w3M4.sub.w4O.sub.w5, the M2 being Al or/and B, the M3 is one or more selected from the group consisting of In, Ti, Zn, Hf, and Zr, the M4 being one or more selected from the group consisting of Sn, Si, and Ge, the w1 and the w5 being numerical values of more than 0, the w2, the w3, and the w4 being numerical values of 0.00 or more, and the w5 when a sum of the w1, the w2, the w3, and the w4 is 2 being 3.00 or more and 3.80 or less, and which is located on the p-type light-absorbing layer side.

Disclosed are a hybrid structure using a graphene-carbon nanotube and a perovskite solar cell using the same. The hybrid structure includes a graphene-carbon nanotube formed by laminating a second graphene coated with a polymer on an upper surface of a first graphene coated with a carbon nanotube. The perovskite solar cell includes: a substrate; a first electrode formed on the substrate and including a fluorine doped thin oxide (FTO); an electron transfer layer formed on the first electrode and including a compact-titanium oxide (c-TiO.sub.2); a mesoporous-titanium oxide (m-TiO.sub.2) formed on the electron transfer layer; a perovskite layer formed on the m-TiO.sub.2 and including a perovskite compound; and a graphene-carbon nanotube hybrid structure formed on the perovskite layer.

An image sensor device includes a semiconductor substrate, a radiation sensing member, a device layer, and a color filter layer. The semiconductor substrate has a photosensitive region and an isolation region surrounding the photosensitive region. The radiation sensing member is embedded in the photosensitive region of the semiconductor substrate. The radiation sensing member has a material different from a material of the semiconductor substrate, and an interface between the radiation sensing member and the isolation region of the semiconductor substrate includes a direct band gap material. The device layer is under the semiconductor substrate and the radiation sensing member. The color filter layer is over the radiation sensing member and the semiconductor substrate.

A solar cell of an embodiment includes a p-electrode; an n-electrode; a p-type light-absorbing layer located between the p-electrode and the n-electrode and mainly containing a cuprous oxide; and an n-type layer located between the first n-type layer and the n-electrode, the n-type layer including a first n-type layer and a second n-type layer or a first n-type region and a second n-type region; wherein the first n-type layer and the first n-type region is located on the p-type light-absorbing layer side, the second n-type layer and the second n-type region is located on the n-electrode side, the first n-type layer and the first n-type region mainly contain a compound represented by Ga.sub.x1M1.sub.x2O.sub.x3, the M1 is one or more selected from the group consisting of Hf, Zr, In, Zn, Ti, Al, B, Sn, Si, and Ge, the x1, the x2, and the x3 are more than 0, and the x3 when a sum of the x1 and the x2 is 2 is 3.0 or more and 3.8 or less, the second n-type layer and the second n-type region mainly contain a compound represented by Ga.sub.y1Zn.sub.y2M2.sub.y3M3.sub.y4O.sub.y5, the M2 is one or more selected from the group consisting of Hf, Zr, In, Ti, Al, B, Si, and Ge, the M3 is Sn or/and Mg, the y1, the y2, the y3, and the y4 are 0 or more, a sum of the y3 and the y4 is more than 0, and the y5 when a sum of the y1, the y2, the y3, and the y4 is 2 is 2.2 or more and 3.6 or less.

A photodetector and an integrated circuit with shortened response time requires a photodetector with an N-type semiconductor layer, a P-type semiconductor layer, and a light absorption layer sandwiched between the N-type semiconductor layer and the P-type semiconductor layer. The light absorption layer includes a layer strained in compression or in tension and a heterostructure which increases the mobility of charge carriers in the light absorption layer.

A photodetector and an integrated circuit with shortened response time requires a photodetector with an N-type semiconductor layer, a P-type semiconductor layer, and a light absorption layer sandwiched between the N-type semiconductor layer and the P-type semiconductor layer. The light absorption layer includes a layer strained in compression or in tension and a heterostructure which increases the mobility of charge carriers in the light absorption layer.

A source and drain electrode are spaced apart by an optically exposed gate region above a surface photovoltage effect (SPV) bulk. A two-dimensional material is deposited upon the gate region. The gate region is activated by exposure to an ultrafast light pulse, which may be infrared or near-infrared, and may be a focused collimated laser pulse with a sub-picosecond width. The pulse causes electron-hole pair generation resulting in band bending in the SPV material, which generates an electric field within the 2D material, thereby modifying the electronic properties between source and drain via a field-effect. After passage of the pulse, conduction continues in the device until the conductive electron-hole pairs recombine during the SPV decay time. The two-dimensional material may comprise a crystalline atomic monolayer. The activation is repeatable with subsequent pulses, resulting in the device cycling on and off within timescales less than 200 picoseconds.

A stacked III-V semiconductor photonic device having a second metallic terminal contact layer at least formed in regions, a highly doped first semiconductor contact region of a first conductivity type, a very low doped absorption region of the first or second conductivity type having a layer thickness of 20 μm-2000 μm, a first metallic terminal contact layer, wherein the first semiconductor contact region extends into the absorption region in a trough shape, the second metallic terminal contact layer is integrally bonded to the first semiconductor contact region and the first metallic terminal contact layer is arranged below the absorption region. In addition, the stacked III-V semiconductor photonic device has a doped III-V semiconductor passivation layer of the first or second conductivity type, wherein the III-V semiconductor passivation layer is arranged at a first distance of at least 10 μm to the first semiconductor contact region.

A stacked III-V semiconductor photonic device having a second metallic terminal contact layer at least formed in regions, a highly doped first semiconductor contact region of a first conductivity type, a very low doped absorption region of the first or second conductivity type having a layer thickness of 20 μm-2000 μm, a first metallic terminal contact layer, wherein the first semiconductor contact region extends into the absorption region in a trough shape, the second metallic terminal contact layer is integrally bonded to the first semiconductor contact region and the first metallic terminal contact layer is arranged below the absorption region. In addition, the stacked III-V semiconductor photonic device has a doped III-V semiconductor passivation layer of the first or second conductivity type, wherein the III-V semiconductor passivation layer is arranged at a first distance of at least 10 μm to the first semiconductor contact region.