Abstract: A GaN single crystal having a full width at half-maximum of the double-crystal X-ray rocking curve of 5-250 sec and a thickness of not less than 80 .mu.m, a method for producing the GaN single crystal having superior quality and sufficient thickness permitting its use as a substrate and a semiconductor light emitting element having high luminance and high reliability, comprising, as a substrate, the GaN single crystal having superior quality and/or sufficient thickness permitting its use as a substrate.

Abstract: A semiconductor light emitting element comprising an n-type semiconductor substrate and a light emitting part comprising an n-type cladding layer composed of an InGaAlP compound semiconductor material, an active layer and a p-type cladding layer formed in that order from the substrate side by double heterojunction, wherein said semiconductor light emitting element satisfies at least one of the following conditions:A. the thickness of said active layer being greater than 0.75 .mu.m and not more than 1.5 .mu.m, andB. the thickness of said p-type cladding layer being 0.5 .mu.m-2.0 .mu.m. According to the light emitting element of the present invention, an overflow of electron into the p-type cladding layer can be suppressed by setting the thickness of the active layer and the p-type cladding layer to fall within the above-mentioned specific ranges, as a result of which the element shows luminous efficiency peaked within the specified range.

Abstract: In the light emitting element comprising an n-type semiconductor substrate, a lower electrode formed on the lower surface of the substrate, and a light emitting part having a pn junction, which is composed of an InGaAlP compound semiconductor material, a p-type current diffusing layer and an upper electrode which are laminated on the upper surface of the substrate in that order from the substrate side, the improvement wherein a carrier concentration of the current diffusing layer is lower on a light emitting part side thereof than that on an upper electrode side thereof, and at least the upper electrode side of the current diffusing layer is composed of GaP. By employing such structure, diffusion of the dopant to a light emitting part can be suppressed even when the carrier concentration of the upper part of the current diffusing layer is set to be higher, thereby affording a lower resistance of the current diffusing layer as a whole.

Abstract: A semiconductor light emitting element comprising a light emitting part comprising an AlGaInP active layer and a AlGaInP cladding layer, which is formed on a GaAs substrate, and an AlGaAs layer and a Ga.sub.x In.sub.1-x P layer (0.7.ltoreq.x.ltoreq.1.0) deposited in this order on said light emitting part, wherein said Ga.sub.x In.sub.1-x P layer has a thickness of not more than 1.0 .mu.m. According to the present invention, absorption of the emitted light by an electrode contact layer and the occurrence of an interfacial distortion between the electrode contact layer and the layer thereunder can be suppressed, and a semiconductor light emitting element permitting easy production thereof and having a high luminance and a long service life can be provided.

Abstract: A semiconductor light emitting element comprising a semiconductor substrate having a lower electrode on its back, a pn junction, a first light reflecting layer disposed between the substrate and the pn junction, an upper electrode, and a second light reflecting layer disposed between the pn junction and the upper electrode, the second light reflecting layer being capable of substantially reflecting the light heading toward the upper electrode, which preferably has, between the pn junction and the second light reflecting layer, a semiconductor layer having a wider bandgap than that of a light emitting layer formed by said pn junction. The semiconductor light emitting element of the invention is advantageous in that the light absorption in the upper electrode can be inhibited to permit efficient output of the light heading toward the upper electrode from the element, and luminance can be greatly increased by the effective output of the light from the element.