A light-emitting diode includes an N-type cladding layer, and a superlattice structure, an active layer, a P-type electron-blocking layer, and a P-type cladding layer disposed on the N-type cladding layer in such order. The superlattice structure includes at least one first layered element which has a sub-layer made of a nitride-based semiconductor material including Al, and having an energy band gap greater than that of said electron-blocking layer. The P-type electron-blocking layer is made of a nitride-based semiconductor material including Al, and has an energy band gap greater than that of the P-type cladding layer.

A light-emitting diode includes an N-type cladding layer, and a superlattice structure, an active layer, a P-type electron-blocking layer, and a P-type cladding layer disposed on the N-type cladding layer in such order. The superlattice structure includes at least one first layered element which has first, second, and third sub-layers that are stacked on one another in a direction away from the N-type cladding layer. The first, second, and third sub-layers have energy band gaps Eg1, Eg2, and Eg3 which satisfy a relationship of Eg1<Eg2<Eg3. In addition, Eg3 is greater than an energy band gap of the P-type electron-blocking layer.

A emitting diode (LED) includes an epitaxial structure defining a base and a mesa on the base. The base defines a light emitting surface of the LED and includes current spreading layer. The mesa includes a thick confinement layer, a light generation area on the thick confinement layer to emit light, a thin confinement layer on the light generation area, and a contact layer on the thin confinement layer, the contact layer defining a top of the mesa. A reflective contact is on the contact layer to reflect a portion of the light emitted from the light generation area, the reflected light being collimated at the mesa and directed through the base to the light emitting surface. In some embodiments, the epitaxial structure grown on a non-transparent substrate. The substrate is removed, or used to form an extended reflector to collimate light.

A transparent thin film display element (100) with a display region(101), and a transition region (105) having a first edge (106) bordering the display region and a second edge (107) opposite to the first edge, the transparent display element having a layer stack (103) comprises:a first conductor layer (110); a second conductor layer (120); andan emissive layer (130) superposed between the first and the second conductor layers and configured to emit light upon electrical current flowing through the emissive layer between the first and the second conductor layers. At least one layer (120) of a group comprising the first and the second conductor layers and the emissive layer has, in the transition region (105), a first coverage at the first edge (106), a second coverage lower than the first coverage at the second edge (107), and an intermediate coverage lying between the first and the second coverage.

A emitting diode (LED) includes an epitaxial structure defining a base and a mesa on the base. The base defines a light emitting surface of the LED and includes current spreading layer. The mesa includes a thick confinement layer, a light generation area on the thick confinement layer to emit light, a thin confinement layer on the light generation area, and a contact layer on the thin confinement layer, the contact layer defining a top of the mesa. A reflective contact is on the contact layer to reflect a portion of the light emitted from the light generation area, the reflected light being collimated at the mesa and directed through the base to the light emitting surface. In some embodiments, the epitaxial structure grown on a non-transparent substrate. The substrate is removed, or used to form an extended reflector to collimate light.

A emitting diode (LED) includes an epitaxial structure defining a base and a mesa on the base. The base defines a light emitting surface of the LED and includes current spreading layer. The mesa includes a thick confinement layer, a light generation area on the thick confinement layer to emit light, a thin confinement layer on the light generation area, and a contact layer on the thin confinement layer, the contact layer defining a top of the mesa. A reflective contact is on the contact layer to reflect a portion of the light emitted from the light generation area, the reflected light being collimated at the mesa and directed through the base to the light emitting surface. In some embodiments, the epitaxial structure grown on a non-transparent substrate. The substrate is removed, or used to form an extended reflector to collimate light.

A method for fabricating quantum rods includes: preparing a Cd-precursor; preparing a S-precursor and CdSe seeds; preparing a Zn-precursor; mixing the S-precursor and the CdSe seeds with the Cd-precursor in a reaction mixture; adding the Zn-precursor to the reaction mixture; stopping the reaction; and performing a purification process to obtain the quantum rods.

In embodiments, an optoelectronic device comprises a substrate formed of magnesium oxide, and a multi-region stack epitaxially deposited upon the substrate. The multi-region stack may comprise a non-polar crystalline material structure along a growth direction, or may comprise a crystal polarity having an oxygen-polar crystal structure or a metal-polar crystal structure along the growth direction. In some cases, at least one region of the multi-region stack is a bulk semiconductor material comprising Mg.sub.(x)Zn.sub.(1-x)O. In some cases, at least one region of the multi-region stack is a superlattice comprising MgO and Mg.sub.(x)Zn.sub.(1-x)O.

Provided are a light-emitting diode and a method of fabricating the same. The light-emitting diode includes a first electrode; a P-type zinc oxide layer which is formed on the first electrode and comprises nano-discs doped with an impurity or nano-rods of zinc oxide doped with an impurity; an N-type zinc oxide layer, which is formed on the P-type zinc oxide layer, comprises nano-rods, and the nano-rods of the N-type zinc oxide layer constitutes homojunction having an epitaxial interface with the P-type zinc oxide layer; and a second electrode, which is formed on the N-type zinc oxide layer.

A composition comprising an engineered defect concentration comprises a metal oxide single crystal having a polar surface and a bulk concentration of interstitial oxygen (O.sub.i) of at least about 10.sup.14 atoms/cm.sup.3. The polar surface comprises a concentration of impurity species of about 5% or less of a monolayer. A method of engineering a defect concentration in a single crystal comprises exposing a metal oxide single crystal having a polar surface to molecular oxygen at a temperature of about 850 C. or less, and injecting atomic oxygen into the single crystal at an effective diffusion rate D.sub.eff of at least about 10.sup.16 cm.sup.2/s.