Abstract: An epitaxial semiconductor crystal plate or wafer capable of attaining increased reliability with enhanced luminance, a manufacturing method thereof, as well as a light-emitting diode (LED). It has been found that epitaxial wafers with enhanced illuminance and increased yield of manufacture can be fabricated by specifically arranging a double-heterostructure epitaxial wafer such that the interface between its p-type clad layer 2 and p-type GaAlAs active layer 3 and that between an n-type GaAlAs clad layer 4 and p-type GaAlAs active layer 3 measure 1×1017 cm−3 or less in oxygen concentration. Also, in order to cause the oxygen concentration near the p-type GaAlAs active layer 3 in layers of the epitaxial wafer to be less than or equal to 1×1017 cm−3, it may be preferable that a nondoped GaAs polycrystal for use as a preselected original material in liquid-phase epitaxial growth be less than or equal to 1×1016 cm−3 or there about.

Abstract: A Light-emitting diode having improved moisture resistance characteristics comprises a p-type gallium arsenide substrate and four epitaxial layers of Al.sub.x Ga.sub.1-x As (22, 23, 24 and 25). These epitaxial layers comprises an intervening layer (22) of p-type Al.sub.x1 Ga.sub.1-x1 As, a cladding layer (23) of p-type Al.sub.x2 Ga.sub.1-x2 As, an active layer (24) of Al.sub.x3 Ga.sub.1-x3 As, and a window layer (25) of Al.sub.x4 Ga.sub.1-x4 As so as to form a double-hetero structure, where x1, x2, x3 and x4 represent mixed crystal ratios of aluminum to arsenic of the layers, respectively, and meet the condition that:x2.gtoreq.x4>x1.gtoreq.x3 (0.ltoreq.x1, x2, x3, x4.ltoreq.1).

Abstract: An epitaxial semiconductor crystal plate or wafer capable of attaining increased reliability with enhanced luminance, a manufacturing method thereof as well as a light-emitting diode (LED). It has been found that epitaxial wafers with enhanced illuminance and increased yield of manufacture can be fabricated by specifically arranging a double-heterostructure epitaxial wafer such that the interface between its p-type clad layer 2 and p-type GaAlAs active layer 3 and that between an n-type GaAlAs clad layer 4 and p-type GaAlAs active layer 3 measure 1.times.10.sup.17 cm.sup.-3 or less in oxygen concentration. Also, in order to cause the oxygen concentration near the p-type GaAlAs active layer 3 in layers of the epitaxial wafer to be less than or equal to 1.times.10.sup.17 cm.sup.-3, it may be preferable that a nondoped GaAs polycrystal for use as a preselected original material in liquid-phase epitaxial growth be less than or equal to 1.times.10.sup.16 cm.sup.-3 or thereabout.

Abstract: A light-emitting diode having improved moisture resistance characteristics comprises a p-type gallium arsenide substrate and four epitaxial layers of Al.sub.x Ga.sub.1-x As (22, 23, 24 and 25). These epitaxial layers comprises an intervening layer (22) of p-type Al.sub.x Ga.sub.1-x As, a cladding layer (23) of p-type Al.sub.x2 Ga.sub.1-x2 As, an active layer (24) of Al.sub.x3 Ga.sub.1-x3 As, and a window layer (25) of Al.sub.x4 Ga.sub.1-x4 As so as to form a double-hetero structure, where x1, x2, x3 and x4 represent mixed crystal ratios of aluminum to arsenic of the layers, respectively, and meet the condition that:x2.gtoreq.x4>x1.gtoreq.x3 (0.ltoreq.x1, x2, x3, x4.ltoreq.1).

Abstract: The present invention relates to the manufacturing process of semi-insulating gallium arsenide single crystal by pulling a seed crystal contacted with gallium arsenide melt which is obtained by heat-reacting gallium and arsenic in a crucible contained in a pressure container and is characteristic in providing a film layer of 8-20 mm thickness of melted boron oxide with less than 200 ppm water content under pressure controlled at 60 kg/cm.sup.2 and over during reaction and at 5-40 kg/cm.sup.2 during crystal growth in high purity inert gas atmosphere, and during said crystal growth, rotating said seed crystal and said crucible in the same direction, but said seed crystal being rotated 5-30 rpm faster than the said crucible, and setting the crystal growing plane of said seed crystal to be within .+-.3.degree. from {100} plane.