Certain embodiments of the present invention may be directed to a transistor structure. The transistor structure may include a semiconductor substrate. The semiconductor substrate may include a drift region, a collector region, an emitter region, and a lightly-doped/undoped region. The lightly-doped/undoped region may be lightly-doped and/or undoped. The transistor structure may also include a heterostructure. The heterostructure forms a heterojunction with the lightly-doped/undoped region. The transistor structure may also include a collector terminal. The collector terminal is in contact with the collector region. The transistor structure may also include a gate terminal. The gate terminal is in contact with the heterostructure. The transistor structure may also include an emitter terminal. The emitter terminal is in contact with the lightly-doped/undoped region and the emitter region.

Disclosed herein are photonic materials. The photonic materials comprise a first layer, a second layer, and a third layer, wherein the second layer is disposed between and in contact with the first layer and the third layer, such that the second layer is sandwiched between the first layer and the third layer. In some examples, the first layer comprises In.sub.yGa.sub.1-.sub.yN, wherein y is from 0 to 0.8. In some examples, the second layer comprises (Zn.sub.aSn.sub.bGe.sub.c).sub.xGa.sub.dN.sub.2, wherein: x is from greater than 0 to 1; a, b, c, and d are each independently from 0 to 1; with the proviso that at least one of a, b, or c is greater than 0. In some examples, the third layer comprises In.sub.zGa.sub.1-.sub.zN, wherein z is from 0 to 0.8.

A device, such as an electroabsorption modulator, can modulate a light intensity by controllably absorbing a selectable fraction of the light. The device can include a substrate. A waveguide positioned on the substrate can guide light. An active region positioned on the waveguide can receive guided light from the waveguide, absorb a fraction of the received light, and return a complementary fraction of the received light to the waveguide. Such absorption produces heat, mostly at an input portion of the active region. The input portion of the active region can be thermally coupled to the substrate, which can dissipate heat from the input portion, and can help avoid thermal runaway of the device. The active region can be thermally isolated from the substrate away from the input portion, which can maintain a relatively low thermal mass for the active region, and can increase efficiency when heating the active region.

Techniques for enhancing the absorption of photons in semiconductors with the use of microstructures are described. The microstructures, such as pillars and/or holes, effectively increase the effective absorption length resulting in a greater absorption of the photons. Using microstructures for absorption enhancement for silicon photodiodes and silicon avalanche photodiodes can result in bandwidths in excess of 10 Gb/s at photons with wavelengths of 850 nm, and with quantum efficiencies of approximately 90% or more.

Tunnel junctions for multijunction solar cells are provided. According to an aspect of the invention, a tunnel junction includes a first layer including p-type AlGaAs, a second layer including n-type GaAs, wherein the second layer is a quantum well, and a third layer including n-type AlGaAs or n-type lattice matched AlGaInP. The quantum well can be GaAs or AlxGaAs with x being more than about 40%, and lattice matched GaInAsNSb in the Eg range of from about 0.8 to about 1.4 eV.

Photovoltaic devices, and methods of fabricating photovoltaic devices. The photovoltaic devices may include a first electrode, at least one quantum dot layer, at least one semiconductor layer, and a second electrode. The first electrode may include a layer including Cr and one or more silver contacts.

Provided is a field shaping multi-well detector and method of fabrication thereof. The detector is configured by depositing a pixel electrode on a substrate, depositing a first dielectric layer, depositing a first conductive grid electrode layer on the first dielectric layer, depositing a second dielectric layer on the first conductive grid electrode layer, depositing a second conductive grid electrode layer on the second dielectric layer, depositing a third dielectric layer on the second conductive grid electrode layer, depositing an etch mask on the third dielectric layer. Two pillars are formed by etching the third dielectric layer, the second conductive grid electrode layer, the second dielectric layer, the first conductive grid electrode layer, and the first dielectric layer. A well between the two pillars is formed by etching to the pixel electrode, without etching the pixel electrode, and the well is filled with a-Se.

An optoelectronic component includes a radiation side, a contact side opposite the radiation side having at least two electrically conductive contact elements, and a semiconductor layer sequence having an active layer that emits or absorbs the electromagnetic radiation, wherein the at least two electrically conductive contact elements have different polarities, are spaced apart from each other and are completely or partially exposed at the contact side in an unmounted state of the optoelectronic component, a region of the contact side is partially or completely covered with an electrically insulating, contiguously formed cooling element, the cooling element is in direct contact with the contact side and has a thermal conductivity of at least 30 W/(m.Math.K), and in a plan view of the contact side, the cooling element partially covers one or both of the at least two electrically conductive contact elements.

The present disclosure provides a photodiode based on a stannous selenide sulfide nanosheet/GaAs heterojunction and a preparation method and use thereof. The photodiode comprises a structure of the stannous selenide sulfide nanosheet/GaAs heterojunction, forming Au electrodes through thermal vapor deposition on the stannous selenide sulfide nanosheet and GaAs, respectively, and conducting an annealing treatment in a protective gas at a temperature in a range of 150-250° C. The heterojunction is formed by transferring the stannous selenide sulfide nanosheet to a GaAs window, and the GaAs window is obtained by depositing a medium layer film on GaAs and etching the medium layer through lithography and an etchant.

An image sensor may include a first photo-sensing device on a semiconductor substrate and configured to sense light of a first wavelength spectrum, and second and third photo-sensing devices integrated in the semiconductor substrate and configured to sense light of a second and third wavelength spectrum, respectively. The first photo-sensing device may overlap each of the second and third photo-sensing devices in a thickness direction of the semiconductor substrate. The second and third photo-sensing devices do not overlap in the thickness direction and each have an upper surface, a lower surface, and a doped region therebetween. The third photo-sensing device includes an upper surface deeper further from the upper surface of the semiconductor substrate than the upper surface of the second photo-sensing device and a doped region thicker than the doped region of the second photo-sensing device. The image sensor may omit the first photo-sensing device.