Abstract: A semiconductor laser exhibiting an oscillation wavelength of 450 nm or less and comprising a substrate, a lower clad layer formed on or above the substrate and mainly composed of a III-V Group compound semiconductor, an active layer formed directly on the lower clad layer and mainly composed of a III-V Group compound semiconductor, and an upper p-type clad layer formed directly on the active layer and mainly composed of a III-V Group compound semiconductor. This semiconductor laser is characterized in that the upper p-type clad layer contains Mg, Si and at least one impurities for compensating residual donors.

Abstract: A light emitting diode is arranged on a sapphire substrate. The light emitting diode includes an n-GaN layer, an n-InGaN light-emitting layer, a p-AlGaN layer and a P-GaN layer, which are grown through vapor phase growth in this sequence. Within the p-GaN layer and p-AlGaN layer, 1.times.10.sup.20 cm.sup.-3 of Mg and 2.times.10.sup.19 cm.sup.-3 of Mg are contained, respectively. Within each of the n-GaN layer and n-InGaN light-emitting layer, 5.times.10.sup.18 cm.sup.-3 of hydrogen is contained, thereby preventing Mg from diffusing therein from the p-GaN layer and p-AlGaN layer.

Abstract: AlN is added to a SiC light emitting layer of an optical semiconductor device in a molecular state, and an association of AlN is formed between crystal lattice points, which are close to each other in said light emitting layer. Said association is largely different from said SiC in degree of electron negativity so that said association traps a carrier in said light emitting layer, and forms an exciton.

Abstract: In a map display system, map-forming data necessary for display of a display area and character data representing display areas are stored in a map data memory. A display area commander reads map-forming data indicating a specified display area out of the map data memory, and produces a display area instruction. A display character commander selects character data for a given point of the specified display area designated by the display area designation commander, and produces a display character instruction. On the basis of the display area instruction from the display area commander and the display character instruction from the display character commander, a map of the specified display area and characters in the specified display area are displayed on a display.