There is provided a semiconductor nanocrystal or quantum dot comprising a core made of a material and at least one shell made of another material. Also there is provided a composite comprising a plurality of such nanocrystals or quantum dots. Moreover, there is provided a method of measuring the temperature of an object or area, comprising using a temperature sensor comprising a semiconductor nanocrystal or quantum dot of the invention.

The disclosure describes multilayer hard magnetic materials including at least one layer including α″-Fe.sub.16N.sub.2 and at least one layer including α″-Fe.sub.16(N.sub.xZ.sub.1-x).sub.2 or a mixture of α″-Fe.sub.16N.sub.2 and α″-Fe.sub.16Z.sub.2, where Z includes at least one of C, B, or O, and x is a number greater than zero and less than one. The disclosure also describes techniques for forming multilayer hard magnetic materials including at least one layer including α″-Fe.sub.16N.sub.2 and at least one layer including α″-Fe.sub.16(N.sub.xZ.sub.1-x).sub.2 or a mixture of α″-Fe.sub.16N.sub.2 and α″-Fe.sub.16Z.sub.2 using chemical vapor deposition or liquid phase epitaxy.

An interface including roughness components for improving the propagation of radiation through the interface is provided. The interface includes a first profiled surface of a first layer comprising a set of large roughness components providing a first variation of the first profiled surface having a first characteristic scale and a second profiled surface of a second layer comprising a set of small roughness components providing a second variation of the second profiled surface having a second characteristic scale. The first characteristic scale is approximately an order of magnitude larger than the second characteristic scale. The surfaces can be bonded together using a bonding material, and a filler material also can be present in the interface.

An interface including roughness components for improving the propagation of radiation through the interface is provided. The interface includes a first profiled surface of a first layer comprising a set of large roughness components providing a first variation of the first profiled surface having a first characteristic scale and a second profiled surface of a second layer comprising a set of small roughness components providing a second variation of the second profiled surface having a second characteristic scale. The first characteristic scale is approximately an order of magnitude larger than the second characteristic scale. The surfaces can be bonded together using a bonding material, and a filler material also can be present in the interface.

Methods of forming a crystalline strontium titanate layer may include providing a substrate with a crystal enhancement surface (e.g., Pt), depositing strontium titanate by atomic layer deposition, and conducting a post-deposition anneal to crystallize the strontium titanate. Large single crystal domains may be formed, laterally extending greater distances than the thickness of the strontium titanate and demonstrating greater ordering than the underlying crystal enhancement surface provided to initiate ALD. Functional oxides, particularly perovskite complex oxides, can be heteroepitaxially deposited over the crystallized STO.

Methods of forming a crystalline strontium titanate layer may include providing a substrate with a crystal enhancement surface (e.g., Pt), depositing strontium titanate by atomic layer deposition, and conducting a post-deposition anneal to crystallize the strontium titanate. Large single crystal domains may be formed, laterally extending greater distances than the thickness of the strontium titanate and demonstrating greater ordering than the underlying crystal enhancement surface provided to initiate ALD. Functional oxides, particularly perovskite complex oxides, can be heteroepitaxially deposited over the crystallized STO.

A quantum dot having core-shell structure includes a core formed of ZnO.sub.zS.sub.1-z, and at least one shell covering the core, and formed of Al.sub.xGa.sub.yIn.sub.1-x-yN, wherein at least one of x, y, and z is not zero and is not one.

A quantum dot having core-shell structure includes a core formed of ZnO.sub.zS.sub.1-z, and at least one shell covering the core, and formed of Al.sub.xGa.sub.yIn.sub.1-x-yN, wherein at least one of x, y, and z is not zero and is not one.

An epitaxial wafer including: a silicon-based substrate; a first buffer layer on the substrate and including a first multilayer structure buffer region composed of Al.sub.xGa.sub.1-xN layers and Al.sub.yGa.sub.1-yN layers (x>y) alternately disposed and a first insertion layer composed of an Al.sub.zGa.sub.1-zN layer (x>z) and is thicker than the Al.sub.yGa.sub.1-yN layer, the first regions and insertion layers alternately disposed; a second buffer layer on the first and including a second multilayer structure buffer region composed of Al.sub.αGa.sub.1-αN layers and Al.sub.βGa.sub.1-βN layers (α>β) alternately disposed and a second insertion layer composed of an Al.sub.γGa.sub.1-γN layer (α>γ) and is thicker than the Al.sub.βGa.sub.1-βN layer, the second regions and insertion layers alternately disposed; and a channel layer on the second buffer layer and thicker than the second insertion layer. The average Al composition in the second buffer layer is higher than that in the first.

An epitaxial wafer including: a silicon-based substrate; a first buffer layer on the substrate and including a first multilayer structure buffer region composed of Al.sub.xGa.sub.1-xN layers and Al.sub.yGa.sub.1-yN layers (x>y) alternately disposed and a first insertion layer composed of an Al.sub.zGa.sub.1-zN layer (x>z) and is thicker than the Al.sub.yGa.sub.1-yN layer, the first regions and insertion layers alternately disposed; a second buffer layer on the first and including a second multilayer structure buffer region composed of Al.sub.αGa.sub.1-αN layers and Al.sub.βGa.sub.1-βN layers (α>β) alternately disposed and a second insertion layer composed of an Al.sub.γGa.sub.1-γN layer (α>γ) and is thicker than the Al.sub.βGa.sub.1-βN layer, the second regions and insertion layers alternately disposed; and a channel layer on the second buffer layer and thicker than the second insertion layer. The average Al composition in the second buffer layer is higher than that in the first.