An improved heterostructure for an optoelectronic device is provided. The heterostructure includes an active region, an electron blocking layer, and a p-type contact layer. The heterostructure can include a p-type interlayer located between the electron blocking layer and the p-type contact layer. In an embodiment, the electron blocking layer can have a region of graded transition. The p-type interlayer can also include a region of graded transition.

A photodiode includes a substrate, a rectifying layer, a buffer layer, a transition layer, an active layer, and an absorption layer. The substrate has a base lattice constant. The rectifying layer is formed on the substrate, and includes an InGaP layer, an AlGaAs layer, and an InGaAs layer which are stacked on the substrate in that order. The rectifying layer includes a connecting layer that is made of GaAs directly formed on one of the InGaP layer and the InGaAs layer. The buffer layer is made of GaAs and stacked on the rectifying layer. The transition layer is formed on the buffer layer, and includes a plurality of sub-layers that each has a lattice constant greater than the base constant but smaller than a designated constant. The active layer is formed on the transition layer and has the designated constant. The absorption layer is formed on the active layer.

A single photon emitter having a ferroelectric film on a substrate, a monolayer or thin film formed on the ferroelectric where the monolayer or thin film contains a single photon emitter, a conductive contact layer formed over a portion of the monolayer or thin film, and an electrical contact adapted to selectively apply a bias voltage to the conductive layer. The ferroelectric film may comprise poly (vinylidene fluoride-co-trifluoroethylene). The monolayer or thin film formed on the ferroelectric may comprise WS.sub.2. Also disclosed is the related method of forming a single photon emitter.

An improved heterostructure for an optoelectronic device is provided. The heterostructure includes an active region, an electron blocking layer, and a p-type contact layer. The heterostructure can include a p-type interlayer located between the electron blocking layer and the p-type contact layer. In an embodiment, the electron blocking layer can have a region of graded transition. The p-type interlayer can also include a region of graded transition.

An improved heterostructure for an optoelectronic device is provided. The heterostructure includes an active region, an electron blocking layer, and a p-type contact layer. The heterostructure can include a p-type interlayer located between the electron blocking layer and the p-type contact layer. In an embodiment, the electron blocking layer can have a region of graded transition. The p-type interlayer can also include a region of graded transition.

A photoelectric conversion element provided in a semiconductor layer having first and second surfaces includes a first region of a first conductivity type, a second region of a second conductivity type closer to the second surface than the first region and forming a p-n junction with the first region, a third region of the first conductivity type closer to the second surface than the second region, a fourth region of the second conductivity type closer to the second surface than the third region, a fifth region of the second conductivity type between the third fourth regions, and a sixth region of the second conductivity type surrounding a region where the first, second, third, and fifth regions are disposed in a plan view. The fifth region has an area smaller than that of the third region in the plan view, and overlaps with the first region in the plan view.

A photoelectric conversion element provided in a semiconductor layer having first and second surfaces includes a first region of a first conductivity type, a second region of a second conductivity type closer to the second surface than the first region and forming a p-n junction with the first region, a third region of the first conductivity type closer to the second surface than the second region, a fourth region of the second conductivity type closer to the second surface than the third region, a fifth region of the second conductivity type between the third fourth regions, and a sixth region of the second conductivity type surrounding a region where the first, second, third, and fifth regions are disposed in a plan view. The fifth region has an area smaller than that of the third region in the plan view, and overlaps with the first region in the plan view.

A quantum dot includes a core and a shell. The core includes a compound semiconductor and has a polyhedral shape. The polyhedral shape includes multiple surfaces and a vertex at which multiple edges between the surfaces adjacent to each other converge. The shell is provided at the surfaces and has a thickness at the part around the vertex in a vertical direction with respect to any one of the surfaces. The thickness is greater than a thickness at a part other than the part around the vertex in the same direction.

A quantum dot includes a core and a shell. The core includes a compound semiconductor and has a polyhedral shape. The polyhedral shape includes multiple surfaces and a vertex at which multiple edges between the surfaces adjacent to each other converge. The shell is provided at the surfaces and has a thickness at the part around the vertex in a vertical direction with respect to any one of the surfaces. The thickness is greater than a thickness at a part other than the part around the vertex in the same direction.

Silver oxide/-gallium oxide heterojunction-based solar blind photodetector includes growing a first conductivity type -gallium oxide epitaxial layer on a first conductivity type -gallium oxide wafer, positioning the first conductivity type -gallium oxide wafer in a sputtering chamber, depositing a second conductivity type silver oxide layer on the first conductivity type -gallium oxide epitaxial layer in a mixed atmosphere of an inert gas and an oxygen gas, blocking a supply of oxygen gas to the sputtering chamber, and depositing a silver layer on the second conductivity type silver oxide layer in the inert gas atmosphere to form a top electrode.