Shin-etsu Handotai Co., Ltd.

Shin-etsu Handotai Kabushiki Kaisha

Susumu Higuchi

Munehisa Yanagisawa

Akio Nakamura

Masato Yamada

Toshio Otaki

Yuuki Tamura

Yuji Yoshida

Masahiko Saito

Ken Aihara

Masahisa Endo

Masanobu Takahashi

Junya Ishizaki

Toru Takahashi

Makoto Kawasaki

Kenji Sakai

Kousei Yumoto

Yu K Tamura

Toshio Ootaki

A semiconductor phosphor configured to exhibit photoluminescence upon irradiation with excitation light, including: at least one active layer made of a compound semiconductor and containing an n-type or p-type dopant; and at least two barrier layers made of a compound semiconductor and having a larger band gap than the active layer. The active layer and the barrier layers are alternately stacked. This provides a semiconductor phosphor which allows easy wavelength adjustment, high efficiency and stability.

Semiconductor phosphor

By providing a nitrogen-doped low carrier concentration layer having both of a donor concentration and an acceptor concentration controlled below 1&times;10 /cm at a p-n junction portion between an n-type GaP layer and a p-type GaP layer the luminance of the GaP light emitting device can be improved by as much as 20 to 30% over the conventional one. Suppressing the donor concentration and the acceptor concentration in the low carrier concentration layer below 1&times;10 /cm inevitably gives a carrier concentration, which is expressed as a difference between both concentrations, lower than 1&times;10 /cm accordingly. The emission efficiency upon injection of electrons or holes can be improved by suppressing the concentration of the donor which serves as non-emissive center below 1&times;10 /cm to thereby extend the carrier lifetime; and by concomitantly suppressing the carrier concentration at a level significantly lower than that in the adjacent layers and

Gallium phosphide luminescent device

An epitaxial wafer comprises epitaxial layers formed on a main surface of a compound semiconductor single crystal substrate , wherein the epitaxial layer on the main surface is exposed in a back surface of the compound semiconductor single crystal substrate , and an exposed portion of the epitaxial layer has a carrier concentration of 1&times;10 cm to 2&times;10 cm . The epitaxial wafer provides for an ultra thin type light emitting diode where generation of ohmic electrode failure is suppressed.

Epitaxial wafer and light emitting diode

While a nitrogen-doped gallium phosphide epitaxial layer in an epitaxial wafer as a material of light-emitting diodes is desired to have a high concentration of nitrogen in order to enhance the efficiency of light emission, the present invention provides a reliable and efficient means to accomplish a high nitrogen concentration by the increase of the concentration of ammonia as a nitrogen source in the doping atmosphere to the contrary to the general understanding that increase of the ammonia concentration to exceed a limit rather has an effect of decreasing the concentration of nitrogen doped in the epitaxial layer. The inventive method is based on the discovery that an exponential relationship is held between the growth rate of the epitaxial layer and the concentration of nitrogen in the thus grown epitaxial layer.

Method for growth of a nitrogen-doped gallium phosphide epitaxial layer

A semiconductor substrate for GaP type light emitting devices which includes an n-type single crystal substrate, an n-type GaP layer, and a p-type GaP layer formed on the n-type GaP single crystal substrate. The carbon concentration in the n-type GaP single crystal substrate is more than 1.0.times.10.sup.16 atoms/cc but less than 1.0.times.10.sup.17 atoms/cc. The n-type GaP single crystal substrate is obtained from an n-type GaP single crystal grown by the Liquid Encapsulation Czochralski method wherein B.sub.2 O.sub.3 containing water corresponding to 200 ppm or more is used as an encapsulation liquid.

Method for fabricating a gap type semiconductor substrate of red light

In an improved liquid phase epitaxial growth method and apparatus in which a plurality of substrates are placed in a deposition chamber having at least one first vent hole; a solution for liquid phase growth is held in a solution chamber having at least one second vent hole and at least two sub-chambers separated by a partition plate and communicated with each other via a communicating portion; and before the substrates and the solution for liquid phase growth are brought into contact with each other, the deposition chamber and the solution chamber are revolved for causing the solution for liquid phase growth to move through the communicating portion so as to increase and decrease the volume of space portions of the respective sub-chambers and thereby replacement of a heat-treatment gas in the deposition chamber and the solution chamber is undertaken to achieve heat treatment. With this heat-treatment, surface oxide films on the substrates and the solution are removed, thus making it possible to obtain a liquid phase epitaxial layer with excellent qualities.

Liquid phase epitaxial

An efficient method is proposed for the determination of the concentration of nitrogen in an indirect-transition compound semiconductor such as gallium phosphide added as an isoelectronic trap. The method utilizes the fact that a good correlation of proportionality is held between the nitrogen concentration and the difference .DELTA..alpha.(=.alpha..sub.N -.alpha.) in the absorption coefficient of light of a wavelength identical with the wavelength .lambda..sub.N due to the excitons under constraint in the isoelectronic trap between the semiconductors with (.alpha..sub.N) and without (.alpha.) addition of nitrogen. A working curve is presented between the nitrogen concentration determined by the method of SIMS and the value of .DELTA..alpha..

Method for the determination of nitrogen concentration in compound

A GaP light emitting element substrate comprising an n-type GaP layer, a nitrogen-doped n-type GaP layer and a p-type GaP layer layered one after another on a multi-layer GaP substrate built by forming an n-type GaP buffer layer(s) on an n-type GaP single crystal substrate, wherein the sulfur (S) concentration in said n-type GaP buffer layer is made to be 5.times.10.sup.16 [atoms/cc] or less. The method of manufacturing it is as follows: an n-type GaP buffer layer(s) is formed on an n-type GaP single crystal substrate to prepare a multi-layer GaP substrate, then an n-type GaP layer, a nitrogen doped n-type GaP layer and a p-type GaP layer are layered on said multi-layer GaP substrate by means of the melt-back method to obtain a GaP light emitting element substrate, wherein the sulfur (S) concentration in said n-type GaP buffer layer is made to be 5.times.10.sup.16 [atoms/cc] or less when the multi-layer GaP substrate is prepared.

GaP light emitting substrate and a method of manufacturing it

Liquid phase epitaxial growth method for carrying out the same

A semiconductor substrate for GaP type light emitting devices which includes an n-type single crystal substrate, an n-type GaP layer, and a p-type GaP layer formed on the n-type GaP single crystal substrate. The carbon concentration in the n-type GaP single crystal substrate is more than 1.0.times.10.sup.16 atoms/cc, but less than 1.0.times.10.sup.17 atoms/cc. The n-type GaP single crystal substrate is obtained from an n-type GaP single crystal grown by the Liquid Encapsulation Czochralski method wherein B.sub.2 O.sub.3 containing water corresponding to 200 ppm or more is used as an encapsulation liquid.

Gap light emitting device having a low carbon content in the substrate

A GaP pure green light emitting element substrate comprising an n-type GaP layer 12 and a p-type GaP layer 14 formed on a GaP single crystal substrate 10, characterized by the fact that an intermediate GaP layer 13 is formed at the pn junction portion between said n-type GaP layer 12 and said p-type GaP layer 14, wherein said intermediate GaP layer has a donor concentration N.sub.D of less than 1.times.10.sup.-16 atoms/cm.sup.3 and an acceptor concentration N.sub.A nearly equal to the donor concentration N.sub.D. The thickness of the intermediate GaP layer 13 is in the range of 3-5 micrometers.

Gap pure green light emitting element substrate

To obtain a GaP light emitting element substrate which provides GaP light emitting diodes with less luminance dispersion and high brightness. A GaP light emitting element substrate comprising an n-type GaP buffer layer, an n-type GaP layer and a p-type GaP layer layered one after another on an n-type GaP single crystal substrate, wherein the oxygen concentration in said n-type GaP buffer layer is kept at 6.times.10.sup.15 [atoms/cc] or less.

GaP light emitting element substrate with oxygen doped buffer

A liquid-phase growth process of a compound semiconductor which is capable of effectively controlling the generation of a surface defect and improve the product quality and production yield is disclosed in which before the start of liquid-phase growth, a substrate and a solution are held in a 100% hydrogen atmosphere or a mixed gas atmosphere consisting of more than 80% of hydrogen and the rest of an inert gas, and immediately before the start of the liquid-phase growth, the atmosphere is changed to a mixed gas atmosphere consisting of not more than 60% of hydrogen and the rest of the inert gas.

Growing community of inventors

Annaka, Japan

Susumu Higuchi