Tokyo Gas Company Limited

Kenji Horiuchi

Satoshi Yamashita

Kazuo Nakamura

Kenichi Nakamura

Takahiro Ide

Takefumi Ishikura

Aki Kawamura

Kenji Maeda

Tokudai Neda

Yasuharu Yokoi

A small, simple current-injection diamond ultraviolet light-emitting device comprising a high-quality diamond grown by chemical vapor deposition (CVD) method (), a surface conductive layer () provided on the surface of the diamond, and electrodes () provided on the surface conductive layer. The device is a free-exciton recombination emission diamond ultraviolet light-emitting device comprising a CVD diamond crystal where the free-exciton recombination radiation (235 nm) caused by current injection is dominant.

Diamond ultraviolet light-emitting device

A nondestructive reading method for an isotopic label, capable of easily and quickly reading information on an isotopic label imparted to an article in advance without destroying the label, and a nondestructive reading-use isotopic label suitably using this method. In addition, information obtained by this nondestructive reading method is used to easily and quickly judge the authenticity of an article.

Nondestructive reading method for isotopic label

A diamond ultraviolet luminescent element () having a current-injection light-emitting diode structure includes a high-quality boron-doped p-type diamond crystal (semiconductor layer) () synthesized by the high pressure and high temperature method; a phosphorous-doped n-type diamond crystal (n-type semiconductor layer) () formed on the first diamond surface by the chemical vapor deposition; an electrode () formed on the surface of the n-type semiconductor layer (); and an electrode () formed on the surface of the p-type semiconductor layer (). The luminescence (235 nm) attributed to the recombination of free excitons resulting from current injection dominates in ultraviolet wavelength region ().

Diamond ultraviolet luminescent element

A current injection-type diamond ultraviolet light-emitting device is provided that achieves the diamond free exciton recombination radiation by forming electrodes on a high-quality diamond crystal and applying a DC voltage between electrodes to inject carriers. A diamond crystal can be selected in terms of photoluminescent spectrum at room temperature and the half width of the Raman scattering peak intrinsic to the diamond.

Growing community of inventors

Tokyo, Japan

Kenji Horiuchi