A composition of matter comprising: a plurality of group III-V nanowires or nanopyramids epitaxially grown on a polycrystalline or single-crystalline graphene layer, said graphene layer being directly supported on a crystalline substrate such as a group III-V semiconductor, sapphire, SiC or diamond substrate, wherein the epitaxy, crystal orientation and facet orientations of said nanowires or nanopyramids are directed by the crystalline substrate.

A photovoltaic system comprises a photovoltaic cell, a substrate, and a light-conversion layer. The photovoltaic cell converts incident light into electricity and is responsive to a range of frequencies of incident light that is less than all frequencies of the incident light. The substrate is disposed between the photovoltaic cell and the incident light so that the incident light passes through the substrate to illuminate the photovoltaic cell. The light-conversion layer is disposed on the substrate so that incident light illuminates the light-conversion layer and the light-conversion layer converts a broad frequency band of incident light outside the range to light within the range and is emitted toward the photovoltaic cell to illuminate the photovoltaic cell with converted light.

An epitaxial structure of a nonpolar AlGaN-based deep-ultraviolet (DUV) photoelectric detector and a preparation method thereof are provided. The epitaxial structure of the nonpolar AlGaN-based DUV photoelectric detector includes a nonpolar AlN buffer layer, a nonpolar Al.sub.0.15Ga.sub.0.85N buffer layer, and a nonpolar Al.sub.0.7Ga.sub.0.3N epitaxial layer that are sequentially grown on a LaAlO.sub.3 substrate. The LaAlO.sub.3 substrate takes a (100) plane as an epitaxial plane, and AlN[11-20] as an epitaxial growth direction. With the LaAlO.sub.3 substrate, the epitaxial structure reduces dislocations and stresses between the substrate and the epitaxial buffer layer. By designing two AlGaN epitaxial buffer layers with different components, the epitaxial structure reduces a dislocation density and a surface roughness of the nonpolar AlGaN epitaxial layer, further accelerates photoresponse and detectivity of the detector, and enhances overall performance of the nonpolar AlGaN-based DUV photoelectric detector.

A device including an activated p-type layer comprising a III-Nitride based Mg-doped layer grown by vapor phase deposition or a growth method different from MBE. The p-type layer is activated through a sidewall of the p-type layer after the removal of defects from the sidewall thereby increasing a hole concentration in the p-type layer. In one or more examples, the device includes an active region between a first n-type layer and the p-type layer; a second n-type layer on the p-type layer; and a tunnel junction between the second n-type layer and the p-type layer, and the activated p-type layer has a hole concentration characterized by a current density of at least 100 Amps per centimeter square flowing between the first n-type layer and the second n-type layer in response to a voltage of 4 volts or less applied across the first n-type layer and the second n-type layer.

The present invention relates to techniques, including methods and devices, for optical technology. In particular, the present invention provides methods, devices, and structures for optical devices, and in particular, photo diodes, commonly called photo sensors.

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-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-zN, wherein z is from 0 to 0.8.