Abstract: The method of manufacturing an optical semiconductor device includes: a mounting step of placing an optical semiconductor chip on a package substrate made of ceramic; a storing step of storing the package substrate after the mounting step in a first dry atmosphere; a placing step of subjecting the optical semiconductor chip on the package substrate to a second dry atmosphere and placing a light transparent window on a joint portion of the package substrate with a joint material therebetween; and a sealing step of joining the joint portion and the light transparent window with the joint material in a low oxygen concentration atmosphere having an oxygen concentration of 1 vol % or less, thereby encapsulating the optical semiconductor chip in a confined space formed by the package substrate and the light transparent window.

Abstract: A deep ultraviolet light-emitting element of this disclosure includes, in this order, an n-type semiconductor layer; a light-emitting layer; and a p-type semiconductor layer. An emission spectrum of the deep ultraviolet light-emitting element has a primary emission peak wavelength in a wavelength range of 200 nm or more and 350 nm or less, and a blue-violet secondary light emission component having a relative emission intensity of 0.03% to 10% across a wavelength range of 430 to 450 nm, a yellow-green secondary light emission component having a relative emission intensity of 0.03 to 10% across a wavelength range of 540 to 580 nm, when the relative emission intensities are expressed relative to an emission intensity at the primary emission peak wavelength taken as 100%. The ratio of an emission intensity at a wavelength of 435 nm to an emission intensity at a wavelength of 560 nm is 0.5 to 2.

Abstract: A deep ultraviolet light-emitting element of this disclosure includes, in this order, an n-type semiconductor layer; a light-emitting layer; and a p-type semiconductor layer. An emission spectrum of the deep ultraviolet light-emitting element has a primary emission peak wavelength in a wavelength range of 200 nm or more and 350 nm or less, and a blue-violet secondary light emission component having a relative emission intensity of 0.03% to 10% across a wavelength range of 430 to 450 nm, a yellow-green secondary light emission component having a relative emission intensity of 0.03 to 10% across a wavelength range of 540 to 580 nm, when the relative emission intensities are expressed relative to an emission intensity at the primary emission peak wavelength taken as 100%. The ratio of an emission intensity at a wavelength of 435 nm to an emission intensity at a wavelength of 560 nm is 0.5 to 2.

Abstract: A method of producing a GaAs single crystal having high carrier concentration and high crystallinity and to provide a GaAs single crystal wafer using such a GaAs single crystal. In the method of producing a GaAs single crystal, a vertical boat method is performed with a crucible receiving a seed crystal, a Si material, a GaAs material serving as an impurity, solid silicon dioxide, and a boron oxide material, thereby growing a GaAs single crystal.

Abstract: A method of producing a GaAs single crystal having high carrier concentration and high crystallinity and to provide a GaAs single crystal wafer using such a GaAs single crystal. In the method of producing a GaAs single crystal, a vertical boat method is performed with a crucible receiving a seed crystal, a Si material, a GaAs material serving as an impurity, solid silicon dioxide, and a boron oxide material, thereby growing a GaAs single crystal.