Abstract: Disclosed is a light-emitting semiconductor device which comprises an N-layer of N-type nitrogen-Group III compound semiconductor satisfying the formula Al.sub.x Ga.sub.y In.sub.1-x-y N, inclusive of x=0, y=0 and x=y=0, a P-layer of P-type nitrogen-Group III compound semiconductor satisfying the formula Al.sub.x Ga.sub.y In.sub.1-x-y N, inclusive of x=0, y=0 and x=y=0 and a Zn doped semi-insulating I-layer of nitrogen-Group III compound semiconductor satisfying the formula Al.sub.x Ga.sub.y In.sub.1-x-y N, inclusive of x=0, y=0 and x=y=0. The semi-insulating I-layer has a 20 to 3000 .ANG. thickness and can emit light in the range of 485 to 490 nm. By employing the I-layer, the light-emitting diode as a whole can emit light in the range of 450 to 480 nm.

Abstract: A light-emitting diode of GaN compound semiconductor emits a blue light from a plane rather than dots for improved luminous intensity. This diode includes a first electrode associated with a high-carrier density n.sup.+ layer and a second electrode associated with a high-impurity density i.sub.H -layer. These electrodes are made up of a first Ni layer (110 .ANG. thick), a second Ni layer (1000 .ANG. thick), an Al layer (1500 .ANG. thick), a Ti layer (1000 .ANG. thick), and a third Ni layer (2500 .ANG. thick). The Ni layers of dual structure permit a buffer layer to be formed between them. This buffer layer prevents the Ni layer from peeling. The direct contact of the Ni layer with GaN lowers a drive voltage for light emission and increases luminous intensity.

Abstract: There are disclosed two types of gallium nitride LED having the pn junction. An LED of gallium nitride compound semiconductor (Al.sub.x Ga.sub.1-x N, where 0.ltoreq.x<1) comprises an n-layer; a p-layer which exhibits p-type conduction upon doping with p-type impurities and irradiation with electron rays, the p-layer joining to the n-layer; a first electrode for the n-layer so as to join to the n-layer, passing through a hole formed in the p-layer which extends from the p-layer to the n-layer; and a second electrode for the p-layer which is formed in a region which is separated by a groove formed in the p-layer so as to extend from the upper surface of the p-layer to said n-layer.

Abstract: A dry etching method for Al.sub.x Ga.sub.1-x N (0.ltoreq.x.ltoreq.1) semiconductor uses plasma of a boron trichloride (BCl.sub.3) gas. The etching rate of the method is 490 .ANG./min. No crystal defect is produced in the etched semiconductor by the dry etching with the plasma of a BCl.sub.3 gas. After etching with the plasma of a BCl.sub.3 gas, the semiconductor is successively etched by an inert gas. The electrode formed on the etched surface is contacted ohmicly with the semiconductor. Ohmic contact can be obtained without sintering. An LED is produced by the dry etching method. The LED comprises a substrate, an n-layer (Al.sub.x Ga.sub.1-x N; 0.ltoreq.x<1), an i-layer, an electrode formed on the etched surface of the n-layer through a through hole, the through hole being formed through the i-layer to the n-layer by the dry etching with the plasma of the born trichloride (BCl.sub.3) gas and being successively etched by the plasma of an inert gas, and an electrode formed on the surface of said i-layer.

Abstract: A dry etching method for Al.sub.x Ga.sub.1-x N(0.ltoreq.x.ltoreq.1) semiconductor is disclosed. The method includes a first method using plasma of carbon tetrachloride (CCl.sub.4) gas, and a second method using plasma of dichlorodifluoromethane (CCl.sub.2 F.sub.2) gas. The etching speed of the former method was 430 .ANG./min. and the etching speed of the latter method was 625 .ANG./min. Also, no crystal defect was produced in the above-mentioned semiconductor by the above-mentioned etching.

Abstract: A vehicle top mark including a base to be fixed to the body of a vehicle, a light-transmitting body that stands on the base, and a light source built into the base. The upper end of the light-transmitting body has an inclined surface that is inclined upward from the front side to the back side, so that the upward light, which passes through the light-transmitting body from the light source, is reflected to the back side of the light-transmitting body. The vehicle top mark is visible to the driver in the nighttime.

Abstract: A light-emitting diode of GaN compound semiconductor emits a blue light from a plane rather than dots for improved luminous intensity. This diode includes a first electrode associated with a high-carrier density n.sup.+ layer and a second electrode associated with a high-impurity density .[.i.sub.H -layer.]. .Iadd.H-layer.Iaddend.. These electrodes are made up of a first Ni layer (110 .ANG. thick), a second Ni layer (1000 .ANG. thick), an Al layer (1500 .ANG. thick), a Ti layer (1000 .ANG. thick), and a third Ni layer (2500 .ANG. thick). The Ni layers of dual structure permit a buffer layer to be formed between them. This buffer layer prevents the Ni layer from peeling. The direct contact of the Ni layer with GaN lowers a drive voltage for light emission and increases luminous intensity.