Riken Corporation

Panasonic Corporation

Sumitomo Electric Industries, Limited

Ulvac, Inc.

Tokyo Ohka Kogyo Co., Ltd.

Toshiba Kikai Kabushiki Kaisha

National Institute for Materials Science

Panasonic Electric Works Co., Ltd.

Dai Nippon Printing Co., Ltd.

National Institute of Advanced Industrial Science and Technology

Ube Industries, Inc.

Dowa Electronics Materials Co., Ltd.

Tamura Corporation

Nippon Tungsten Co., Ltd.

Shibaura Machine Co., Ltd.

Hideki Hirayama

Takayoshi Takano

Takaharu Tashiro

Ryuichiro Kamimura

Yamato Osada

Yukio Kashima

Eriko Matsuura

Mitsunori Kokubo

Katsushi Akita

Kenji Tsubaki

Takao Nakamura

Yoshinobu Aoyagi

Norimichi Noguchi

Takuya Mino

Masafumi Jo

Jun Sakai

Takafumi Ookawa

Sachie Fujikawa

Takashi Kyono

Toshiro Morita

Satoshi Shimatani

Noritoshi Maeda

Tsung-Tse Lin

Hideki Takagi

Yukihiro Kondo

Hideki Miyazaki

Sung Won Youn

Norihiko Kamata

Tomoaki Ohashi

Sohachi Iwai

Li Wang

Kanna Aoki

Yasuhiro Watanabe

Tomohiko Shibata

Takeshi Iwai

Robert David Armitage

Miho Sasaki

Hiromi Nishihara

Hitomichi Takano

Yasuyuki Ichizono

Yoshikatsu Morishima

Junji Ikeda

Yohei Aoyama

Yasushi Iwaisako

Wataru Terashima

Tsugumi Nagano

Ke Wang

Kanji Furuta

Souhachi Iwai

In order to provide a QCL element operating in the near-infrared wavelength range, the present disclosure provides a quantum cascade laser elementhaving a semiconductor superlattice structure (QCL structure) sandwiched between a pair of conductive sectionsand. The semiconductor superlattice structure serves as an active region that emits electromagnetic waves. The active region has a plurality of unit structuresU that are stacked on top of each other. Each unit structure includes four well layersW-Wof a composition of AlGaN, separated from each other by barrier layersB-Bof a composition of AlGaN with 0&#x2264;x&#x3c;y&#x2264;1. Both of the conductive sections in the pair of conductive sections have a refractive index lower than that of the active region in which doped TCO inserted as a key role.

Quantum cascade laser element

A deep ultraviolet LED with a design wavelength &#x3bb;, including a reflecting electrode layer (Au), a metal layer (Ni), a p-GaN contact layer, a p-block layer made of a p-AlGaN layer, an i-guide layer made of an AlN layer, a multi-quantum well layer, an n-AlGaN contact layer, a u-AlGaN layer, an AlN template, and a sapphire substrate that are arranged in this order from a side opposite to the sapphire substrate, in which the thickness of the p-block layer is 52 to 56 nm, a two-dimensional reflecting photonic crystal periodic structure having a plurality of voids is provided in a region from the interface between the metal layer and the p-GaN contact layer to a position not beyond the interface between the p-GaN contact layer and the p-block layer in the thickness direction of the p-GaN contact layer, the distance from an end face of each of the voids in the direction of the sapphire substrate to the interface between the multi-quantum well layer and the i-guide layer satisfies &#x3bb;/2n(where &#x3bb; is the design wavelength and n1Deff is the effective average refractive index of each film of the stacked structure from the end face of each void to the i-guide layer) in the perpendicular direction, the distance being in the range of 53 to 57 nm, the two-dimensional reflecting photonic crystal periodic structure has a photonic band gap that opens for TE polarized components, and provided that the period a of the two-dimensional reflecting photonic crystal periodic structure satisfies a Bragg condition with respect to light with the design wavelength &#x3bb;, the order m of a formula of the Bragg condition: m&#x3bb;/n=2(where m is the order, &#x3bb; is the design wavelength, nis the effective refractive index of two-dimensional photonic crystals, and a is the period of the two-dimensional photonic crystals) satisfies 2&#x2264;m&#x2264;4, and the radius of each void is R, R/a satisfies 0.30&#x2264;R/a&#x2264;0.40.

Deep ultraviolet LED and method for producing the same

Provided is a deep ultraviolet LED with a design wavelength &#x3bb;, including a reflecting electrode layer, an ultra-thin metal layer, and a p-type contact layer that are arranged in this order from a side opposite to a substrate; and a hemispherical lens bonded to a rear surface of the substrate on a side of the p-type contact layer, the hemispherical lens being transparent to light with the wavelength &#x3bb;. The refractive index of the hemispherical lens is greater than or equal to the average value of the refractive index of the substrate and the refractive index of air and is less than or equal to the refractive index of the substrate. The hemispherical lens has a radius that is greater than or equal to the radius of an inscribed circle of the substrate and is about equal to the radius of a circumscribed circle of the substrate.

Deep ultraviolet LED and method for manufacturing the same

An ultraviolet light-emitting element includes: a multilayer stack in which an n-type AlGaN layer, a light-emitting layer, a first p-type AlGaN layer, and a second p-type AlGaN layer are arranged in this order; a negative electrode; and a positive electrode. The first p-type AlGaN layer has a larger Al composition ratio than first AlGaN layers serving as well layers. The second p-type AlGaN layer has a larger Al composition ratio than the first AlGaN layers. The first p-type AlGaN layer and the second p-type AlGaN layer both contain Mg. The second p-type AlGaN layer has a higher maximum Mg concentration than the first p-type AlGaN layer. The second p-type AlGaN layer includes a region where an Mg concentration increases in a thickness direction thereof as a distance from the first p-type AlGaN layer increases in the thickness direction.

Ultraviolet light-emitting element

An epitaxial substrate includes: a single crystal substrate including projections arranged in an array on a plane. Each projection has a conical or pyramidal shape tapered in a normal direction to the plane. The AlN layer includes: a first AlN crystal covering the plane and the projections with tips of the projections being exposed; second AlN crystals protruding from the tips of the projections along the normal direction and each having a shape of a column whose cross-sectional area increases as a distance from a tip of a corresponding projection increases; and a third AlN crystal as a layer interconnecting ends of the second AlN crystals, opposite the single crystal substrate.

Epitaxial substrate

To increase the maximum operating temperature of quantum cascade lasers of a terahertz region, a quantum cascade laser elementaccording to the present invention has a semiconductor superlattice structure sandwiched between a pair of electrodes, the semiconductor superlattice structure has an active regionthat emits electromagnetic waves of a frequency in a THz region under an external voltage applied through the pair of electrodes for operation, and the active regionhas plural unit structuresU, each of which is repeatedly layered over one another. Each of the unit structuresU has a double quantum well structure formed of a first well layerWand a second well layerWseparated from each other by a barrier layer, the first well layerWand the second well layerWhave compositions different from each other, and when the external voltage is not being applied, potential energy for electrons in the second well layerWis lower than that in the first well layerW

A UV LED element, which is an exemplary ultraviolet light-emitting diode according to the present invention, includes an n-type conductive layer, a light-emitting layer, an electron block layer, and a p-type contact layer, all of which are arranged in this order. Bandgap energy of the electron block layer satisfies E&#x2264;E, where Edesignates bandgap energy of the p-type contact layer and Edesignates the bandgap energy of the electron block layer. The electric apparatus includes the UV LED element as a light source for emitting an ultraviolet ray.

Ultraviolet light-emitting diode and electric apparatus provided with the same

To fabricate a practically useful non-polar AlN buffer layer on a sapphire crystal plate and manufacture a UV light-emitting device on a non-polar crystal substrate by adopting the crystal substrate as an example, an embodiment of the present invention provides a crystal substrateD comprising an r-plane sapphire crystal plateand an AlN buffer layerD of non-polar orientation. The AlN buffer layer comprises a surface protection layerand a smoothing layer. The surface protection layer suppresses roughness increase on a surface of the AlN buffer layer, and the smoothing layer makes the surface of the AlN buffer layer a smoothed surface. Also provided is a crystal substratecomprising an AlN buffer layerT to which a dislocation blocking layerfor reducing crystallographic defects is added between the surface protection layerand the smoothing layer. In another embodiment a deep UV light-emitting device is provided.

Crystal substrate, ultraviolet light-emitting device, and manufacturing methods therefor

The light extraction efficiency of a deep ultraviolet LED is increased. The deep ultraviolet LED has a design wavelength &#x3bb;, and includes, sequentially arranged from a side opposite to a substrate, a reflecting electrode layer, a metal layer, a p-GaN contact layer, a p-AlGaN layer that is transparent to light with the wavelength &#x3bb;, one of a multi-quantum barrier layer or an electron blocking layer, a barrier layer, and a quantum well layer. A thickness of the p-AlGaN layer is less than or equal to 100 nm. A reflecting photonic crystal periodic structure having a plurality of voids is provided in a region in a thickness direction including at least an interface between the p-GaN contact layer and the p-AlGaN layer such that the reflecting photonic crystal periodic structure does not extend beyond the p-AlGaN layer in a direction of the substrate. Maximum light extraction efficiency is obtained when a distance from end faces of the voids in the direction of the substrate to the quantum well layer is greater than or equal to a total thickness of the barrier layer and the multi-quantum barrier layer (or the electron blocking layer) and less than or equal to 80 nm, and a depth h of each void is less than or equal to a total thickness of the p-AlGaN layer and the p-GaN contact layer. The reflecting photonic crystal periodic structure has a photonic band gap that opens for TE polarized components. A period a of the photonic crystal periodic structure satisfies a Bragg condition with respect to light with the design wavelength &#x3bb;. An order m in a formula of the Bragg condition satisfies 1&#x2264;m&#x2264;5. Provided that a radius of each void is R, R/a with which the photonic band gap becomes maximum is satisfied.

Provided is a deep ultraviolet LED with a design wavelength &#x3bb;, including an Al reflecting electrode layer, an ultrathin metal layer, and a transparent p-AlGaN contact layer that are sequentially arranged from a side opposite to a substrate, and a photonic crystal periodic structure provided in the range of the thickness direction of the transparent p-AlGaN contact layer. The photonic crystal periodic structure has a photonic band gap.

A semiconductor light emitting element with a design wavelength of &#x3bb;, comprising a photonic crystal periodic structure having two structures with different refractive indices at each of one or more interfaces between layers that form the light emitting element. The period a and the radius R that are parameters of each of the one or more periodic structures and the design wavelength &#x3bb; satisfy Bragg conditions. The ratio (R/a) between the period a and the radius R is a value determined so that a predetermined photonic band gap (PBG) for TE light becomes maximum for each periodic structure. The parameters of each periodic structure are determined so that light extraction efficiency of the entire semiconductor light emitting element with respect to light with the wavelength &#x3bb; becomes maximum as a result of conducting a simulation analysis with a FDTD method using as variables the depth h of the periodic structure that is of greater than or equal to 0.5a and the period a and the radius R that are determined for each order m of the Bragg conditions.

Semiconductor light emitting element and method for producing the same

An ultraviolet light emitting element includes a light emitting layer, a cap layer, an electron barrier layer. The light emitting layer has a multi-quantum well structure including barrier layers each including a first AlGaN layer and well layers each including a second AlGaN layer. The electron barrier layer includes at least one first p-type AlGaN layer and at least one second p-type AlGaN layer. The cap layer is located between the first p-type AlGaN layer and one of the well layers closest to the first p-type AlGaN layer. The cap layer is a third AlGaN layer having an Al composition ratio greater than an Al composition ratio of each of the well layers and less than an Al composition ratio of the first p-type AlGaN layer. The cap layer has a thickness of greater than or equal to 1 nm and less than or equal to 7 nm.

Ultraviolet light emitting element and electrical device using same

A deep ultraviolet LED with a design wavelength of &#x3bb; is provided that includes a reflecting electrode layer, a metal layer, a p-type GaN contact layer, and a p-type AlGaN layer that are sequentially stacked from a side opposite to a substrate, the p-type AlGaN layer being transparent to light with the wavelength of &#x3bb;; and a photonic crystal periodic structure that penetrates at least the p-type GaN contact layer and the p-type AlGaN layer. The photonic crystal periodic structure has a photonic band gap.

An ultraviolet LED having increased light extraction efficiency includes: a single crystal sapphire substrate on which an array of protruding portions are formed; an AlN crystal buffer layer formed on the sapphire substrate; and an ultraviolet light emitting layer, in contact with the buffer layer, formed into a layered stack including an n-type conductive layer, a recombination layer, and a p-type conductive layer, in order from the buffer layer. The buffer layer includes a pillar array section and an integration section wherein pillars in the array are connected with one another. Each pillar extends from a protruding portion of the sapphire substrate, in a direction normal to one surface thereof. The pillars are separated from one another in the plane of the surface by a gap G. Light emitted from the ultraviolet light emitting layer is extracted to the outside through the pillar array section and the sapphire substrate.

Ultraviolet light emitting diode and method for producing same

Growing community of inventors

Saitama, Japan

Hideki Hirayama