Kabushiki Kaisha Toshiba

Nobuhiro Suzuki

Hideto Sugawara

Chisato Furukawa

Koichi Nitta

Satoshi Komoto

Kuniaki Konno

Masayuki Ishikawa

A light emitting device or image display includes a fluorescent material as a wavelength converter for converting a wavelength into another. The fluorescent material is disposed in a predetermined positional relation, to prevent external leakage of primary light and to extract secondary light made by wavelength-converting the primary light with a very high efficiency. By using a semiconductor light emitting element for ultraviolet emission and combining it with a fluorescent material or any other appropriate material having a wavelength converting function, various kinds of applications, such as illuminator, having a remarkably long-life light source can be made. The semiconductor light emitting element preferably has a emission wavelength near 330 nm, and preferably uses BGaN in its light emitting layer.

Semiconductor light emitting device including a fluorescent material

There is disclosed a semiconductor light emitting element formed by selective growth and being high in light emitting efficiency, in which at least one GaN-based layer grown by ELO is stacked/formed on a sapphire substrate, and a fluorescent substance for converting an ultraviolet light to a visible light is contained in a selective growth mask material layer for use in this case. Since this fluorescent substance converts the ultraviolet light to the visible light, a binding efficiency of the ultraviolet light to the fluorescent substance is enhanced in either one of a center light emitting type and UV light emitting type of light emitting elements. By further containing the fluorescent substance into a passivation film, the efficiency is further enhanced.

Semiconductor light emitting element and manufacturing method thereof

According to the invention, there is provided a semiconductor light emitting device comprising: a contact layer formed of a nitride semiconductor; and a p-side electrode provided in contact with a surface of the contact layer, the contact layer having a superlattice including an alternative stacked structure of first nitride semiconductor layers having a wider bandgap and second nitride semiconductor layers having a narrower bandgap, the first semiconductor layers being selectively doped with a p-type dopant.

Semiconductor light emitting device

A nitride compound semiconductor light emitting element comprises a substrate, a nitride compound semiconductor n-type layer, a mask layer having a predetermined opening, a nitride compound semiconductor buffer layer epitaxially grown on said n-type layer exclusively at said opening. The buffer layer has a recess on its top face so that a thickness of said buffer layer is thinner above a central portion of the opening and thicker above edge portions of the opening. A nitride compound semiconductor active layer is selectively formed on the recess of the buffer layer to be thicker at the central portion of the recess and thinner at the edges of the recess. A nitride compound semiconductor burying layer overlays the mask layer and the active layer to cover the active layer. By selectively growing the buffer layer and the active layer in the opening of the mask layer formed on the substrate and by growing additional layers to bury the entire structure and to flatten the surface, a planar-type, stripe-buried structure is realized. The active layer has a distribution of refractive index due to the distribution of thickness resulting from the selective growth and can confine light with high efficiency. Additionally, by using an insulation film, highly efficient confinement of current is realized to provide a light emitting element for a shorter wavelength with a high luminous intensity and a low oscillation threshold value.

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Yokohama, Japan

Nobuhiro Suzuki