Abstract: The gallium arsenide single crystal substrate has a circular main surface, and when the diameter of the main surface of the gallium arsenide single crystal substrate is represented by D and the number of etch pits formed on the main surface by immersing the gallium arsenide single crystal substrate in molten potassium hydroxide at 500° C. for 10 minutes is counted, the number C1 of etch pits in a first circular region having a diameter of 0.2D around the center of the main surface is 0 or more and 10 or less.

Abstract: The gallium arsenide single crystal substrate has a circular main surface, and when the diameter of the main surface of the gallium arsenide single crystal substrate is represented by D and the number of etch pits formed on the main surface by immersing the gallium arsenide single crystal substrate in molten potassium hydroxide at 500° C. for 10 minutes is counted, the number C1 of etch pits in a first circular region having a diameter of 0.2D around the center of the main surface is 0 or more and 10 or less.

Abstract: Affords AlxGa(1-x)As (0?x?1) substrates epitaxial wafers for infrared LEDs, infrared LEDs, methods of manufacturing AlxGa(1-x)As substrates, methods of manufacturing epitaxial wafers for infrared LEDs, and methods of manufacturing infrared LEDs, whereby a high level of transmissivity is maintained, and through which, in the fabrication of semiconductor devices, the devices prove to have superior light output characteristics. An AlxGa(1-x)As substrate (10a) as disclosed is an AlxGa(1-x)As substrate (10a) furnished with an AlxGa(1-x)As layer (11) having a major surface (11a) and, on the reverse side from the major surface (11a), a rear face (11b), and is characterized in that in the AlxGa(1-x)As layer (11), the amount fraction x of Al in the rear face (11b) is greater the amount fraction x of Al in the major surface (11a). The AlxGa(1-x)As substrate (10a) may additionally be provided with a GaAs substrate (13), contacting the rear face (11b) of the AlxGa(1-x)As layer (11).

Abstract: The present invention makes available AlxGa(1-x)As (0?x?1) substrates, epitaxial wafers for infrared LEDs, infrared LEDs, methods of manufacturing AlxGa(1-x)As substrates, methods of manufacturing epitaxial wafers for infrared LEDs, and methods of manufacturing infrared LEDs, whereby a high level of transmissivity is maintained, and through which, in the fabrication of semiconductor devices, the devices prove to have superior characteristics. An AlxGa(1-x)As substrate (10a) of the present invention is an AlxGa(1-x)As substrate (10a) furnished with an AlxGa(1-x)As layer (11) having a major surface (11a) and, on the reverse side from the major surface (11a), a rear face (11b), and is characterized in that in the AlxGa(1-x)As layer (11), the amount fraction x of Al in the rear face (11b) is greater than the amount fraction x of Al in the major surface (11a).

Abstract: Affords AlxGa(1-x)As (0?x?1) substrates, epitaxial wafers for infrared LEDs, infrared LEDs, methods of manufacturing AlxGa(1-x)As substrates, methods of manufacturing epitaxial wafers for infrared LEDs, and methods of manufacturing infrared LEDs, whereby a high level of transmissivity is maintained, and through which, in the fabrication of semiconductor devices, the devices prove to have superior characteristics. An AlxGa(1-x)As substrate (10a) of the present invention is an AlxGa(1-x)As substrate (10a) furnished with an AlxGa(1-x)As layer (11) having a major surface (11a) and, on the reverse side from the major surface (11a), a rear face (11b), and is characterized in that in the AlxGa(1-x)As layer (11), the amount fraction x of Al in the rear face (11b) is greater than the amount fraction x of Al in the major surface (11a). In addition, the AlxGa(1-x)As substrate (10a) is further furnished with a GaAs substrate (13), contacting the rear face (11b) of the AlxGa(1-x)As layer (11).

Abstract: A semiconductor light emitting device including a transparent compound semiconductor substrate whose lattice constant is inconsistent with the compound semiconductor emitting the light and exhibiting high light output is obtained. A semiconductor light emitting device includes a GaP substrate, an active layer located above GaP substrate and including an n-type AlInGaP layer and a p-type AlInGaP layer, and an ELO layer located between GaP substrate and active layer and formed by epitaxial lateral growth.