A solar cell employing nanocrystalline superlattice material and amorphous structure and method of constructing the same provides improved efficiency when converting sunlight to power. The photovoltaic (PV) solar cell includes an intrinsic superlattice material deposited between the p-doped layer and the n-doped layer. The superlattice material is comprised of a plurality of sublayers which effectively create a graded band gap and multi-band gap for the superlattice material. The sublayers can include a nanocrystalline Si:H layer, an amorphous SiGe:H layer and an amorphous SiC:H layer. Varying the thickness of each layer results in an effective energy gap that is graded as desired for improved efficiency. Methods of constructing single junction and parallel configured two junction solar cells include depositing the various layers on a substrate such as stainless steel or glass.

A semiconductor device comprises a plurality of quantum structures comprising predominantly germanium. The plurality of quantum structures are formed on a first semiconductor layer structure. The quantum structures of the plurality of quantum structures have a lateral dimension of less than 15 nm and an area density of at least 810.sup.11 quantum structures per cm.sup.2. The plurality of quantum structures are configured to emit light with a light emission maximum at a wavelength of between 2 m and 10 m or to absorb light with a light absorption maximum at a wavelength of between 2 m and 10 m.

A photosensitive element includes a semiconductor substrate, a first contact region connected to a first contact, and a second contact region connected to a second contact. The semiconductor substrate has a radiation receiving area through which an incident radiation can enter the photosensitive element and a radiation reflecting area disposed on a side of the semiconductor substrate opposite the radiation receiving area. A multiplication region multiplying a plurality of charges generated from the incident radiation is formed at the first contact region when a voltage is applied between the first contact and the second contact. The first contact and the second contact are arranged on the side of the semiconductor substrate opposite the radiation receiving area.

The present disclosure provides a photo sensing device and a method for forming a photo sensing device. The photo sensing device includes a substrate, a photosensitive member, a superlattice layer and a diffusion barrier structure. The substrate includes a silicon layer at a front surface. The photosensitive member extends into and at least partially surrounded by the silicon layer, wherein an upper portion of the photosensitive member protruding from the silicon layer has a top surface and a facet tapering toward the top surface. The superlattice layer is disposed between the photosensitive member and the silicon layer. The diffusion barrier structure is disposed at a first side of the photosensitive member and a bottom of the diffusion barrier structure is at a level below a top surface of the silicon layer, wherein at least a portion of the diffusion barrier structure is laterally surrounded by the silicon layer.