An object is to provide a new type of near-infrared ray-emitting phosphor which exhibits excellent emission intensity. A near-infrared ray-emitting phosphor is represented by a general formula, (Y,Lu,Gd).sub.3-x-y (Ga,Al,Sc).sub.5O.sub.12:(Cr.sub.x,(Yb,Nd).sub.y) (0.05<x<0.3, 0≤y<0.3).

Systems and methods to provide multiple channels of light to form a blended white light output, the systems and methods utilizing recipient luminophoric mediums to alter light provided by light emitting diodes. The predetermined blends of luminescent materials within the luminophoric mediums provide predetermined spectral power distributions in the white light output.

A nitride phosphor particle dispersion-type sialon ceramic of the present invention includes a matrix formed of a sialon-based compound; and at least one nitride phosphor which is dispersed in the matrix and contains a luminescence center element.

A backlight device includes an LED substrate including LED devices arrayed and a quantum dot layer disposed to receive light output from the LED devices. Each LED device emits first blue light and at least one of first green light and first red light, and when relative radiance of the first blue light is 1.00, relative radiance of the first green light is 0.21 or less and relative radiance of the first red light is 0.48 or less. The quantum dot layer includes, in accordance with the at least one of the first green light and the first red light, at least one of a green quantum dot excited by the first blue light and emitting second green light and a red green quantum dot excited by the first blue light and emitting second red light, and the quantum dot layer contains 300 ppm or less of cadmium.

A backlight device includes an LED substrate including LED devices arrayed and a quantum dot layer disposed to receive light output from the LED devices. Each LED device emits first blue light and at least one of first green light and first red light, and when relative radiance of the first blue light is 1.00, relative radiance of the first green light is 0.21 or less and relative radiance of the first red light is 0.48 or less. The quantum dot layer includes, in accordance with the at least one of the first green light and the first red light, at least one of a green quantum dot excited by the first blue light and emitting second green light and a red green quantum dot excited by the first blue light and emitting second red light, and the quantum dot layer contains 300 ppm or less of cadmium.

A material represented by the following formula (I)
(M).sub.8M.sub.6M.sub.6O.sub.24(X,S).sub.2:Mformula (I).
Also disclosed is an ultraviolet radiation sensing material, an X-radiation sensing material, a device and a method for determining the intensity of ultraviolet radiation.

Heterostructures containing one or more sheets of positive charge, or alternately stacked AlGaN barriers and AlGaN wells with specified thickness are provided. Also provided are multiple quantum well structures and p-type contacts. The heterostructures, the multiple quantum well structures and the p-type contacts can be used in light emitting devices and photodetectors.

A -sialon phosphor represented by general formula: Si.sub.6zAl.sub.zO.sub.zN.sub.8z (0<z<4.2) has as a host crystal, a crystal structure identical to that of a -sialon crystal phase and having a bulk density of 0.80 g/cm.sup.3 or more and 1.60 g/cm.sup.3 or less. Also, a light-emitting element includes the -sialon phosphor and a semiconductor light-emitting element capable of exciting the -sialon phosphor.

A wavelength conversion member is provided which includes a phosphor layer having an increased pencil hardness and thereby has a reduced risk of breakage such as scattering of fragments of the phosphor layer or separation of the phosphor layer. A substrate 12 is made of sapphire, and a phosphor layer 14 is disposed on the substrate 12 and includes phosphor particles 16 and a light transmissive inorganic material 22. The phosphor layer 14 has a pencil hardness of 5B or above. The high hardness of the phosphor layer 14 reduces the risk of breakage such as the phosphor layer 14 being scattered as fragments or being separated from the substrate 12.

A light-emitting device includes a light-emitting element having a top surface, a bottom surface opposite to the top surface, and side surfaces connecting the top surface and the bottom surface. An element electrode of the light-emitting element is located on the bottom surface. A phosphor layer is disposed above the top surface of the light-emitting element and having side surfaces. A reflective member covers side surfaces of the light-emitting element and side surfaces of the phosphor layer. A dielectric multilayer film is disposed on at least one of the side surfaces of the light-emitting element and disposed on at least one of the side surfaces of the phosphor layer and not located between the light emitting element and the phosphor layer. The dielectric multilayer film is not provided on an upper surface of the phosphor layer.