Shin-etsu Handotai Co., Ltd.

Shin-etsu Handotai Kabushiki Kaisha

Munehisa Yanagisawa

Susumu Higuchi

Yuuki Tamura

Akio Nakamura

Toshio Otaki

Susumu Arisaka

Masato Yamada

Hidetoshi Matsumoto

Masahiko Saito

Yuji Yoshida

Yu K Tamura

Toshio Ootaki

Yuki Tamura

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

An apparatus of measuring a surface shape, which enables the surface shape of a sample to be accurately and quantitatively measured by a simple procedure, is provided. A sample 1 is placed on a sample stage 3, a light is projected by an optical system 8 on the sample 1, the sample stage 3 is tilted at intervals of a unit angle and on the basis of a prescribed surface by a motor 6, a reflected light from the sample 1 is received by a CCD 16, and an operational analysis circuit 21, in response to a command from a CPU 17 and based on the data of light reception obtained by the CCD 16 at intervals of a unit tilting angle, performs an operational analysis on the surface shape of the sample.

Apparatus for measuring surface shape

Liquid phase epitaxial growth method for carrying out the same

This disclosure herein pertains to a method for producing a GaP epitaxial wafer used for fabrication of light emitting diodes having higher brightness than light emitting diodes fabricated from a GaP epitaxial wafer produced by a conventional method have. The method comprises the steps of: preparing a GaP layered substrate 15 with one or more GaP layers on a GaP single crystal substrate 10 in the first series of liquid phase epitaxial growth; obtaining a layered GaP substrate 15a by eliminating surface irregularities of said GaP layered substrate 15 by mechano-chemical polishing to make the surface to be planar; and then forming a GaP light emitting layer composite 19 on said layered GaP substrate 15a in the second series of liquid phase epitaxial growth.

Method for producing a gallium phosphide epitaxial wafer

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

To provide a GaP red light emitting element substrate which a large amount of oxygen is doped in the p-type GaP layer, and which very few Ga.sub.2 O.sub.3 precipitates develop on and/or in p-type GaP layer, and methods of manufacturing said substrate. After the n-type GaP layer 2 is grown on the n-type GaP single crystal substrate 1, when forming the p-type GaP layer 3 doped with Zn and O, on said n-type GaP layer 2 by means of the liquid phase epitaxial growth method, the p-type GaP layer 3 is grown by using a Ga solution with a high concentration of oxygen, and said Ga solution is removed from the substrate 1 to complete the growth when the temperature is lowered to a prescribed temperature of 980.degree. C. or higher. When the temperature has reached the prescribed temperature of 980.degree. C. or higher during the growth using the Ga solution with a high concentration of oxygen, it is also possible to treat said Ga solution to decrease the concentration of the contained oxygen and then continue the growth. It is also possible to conduct the growth using the Ga solution with a high concentration of oxygen until the temperature reaches the prescribed temperature of 980.degree. C. or higher, and then, after switching the growth solution to a Ga solution with a low concentration of oxygen, continue the growth.

Method of making gap red light emitting element substrate by LPE

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 GaP red light emitting diode (LED) which is free from a problem of luminance reduction comprises an n-type GaP epitaxial layer grown on an n-type GaP substrate, and a p-type GaP epitaxial layer grown on the n-type Gap epitaxial layer, wherein the n-type epitaxial layer has an Si concentration of not more than 5.times.10.sup.17 atoms/cc and an S concentration of not more than 1.times.10.sup.18 atoms/cc.

Gap red light emitting diode

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

Takasaki, Japan

Munehisa Yanagisawa