Abstract: A nitride-based semiconductor laser device capable of preventing deterioration in the vicinity of a facet is obtained. This nitride-based semiconductor laser device comprises a first conductivity type first cladding layer consisting of a nitride-based semiconductor formed on a substrate, an active layer formed on the first cladding layer, a second conductivity type second cladding layer consisting of a nitride-based semiconductor formed on the active layer and a high-resistance region formed at least portions of the active layer and the second cladding layer in the vicinity of the facet. The high-resistance region has higher resistance than the remaining regions, whereby a current hardly flows to the high-resistance region. Thus, temperature increase is suppressed in the vicinity of the facet, whereby deterioration can be prevented in the vicinity of the facet.

Abstract: A nitride-based semiconductor element enabling formation of a nitride-based semiconductor layer having low dislocation density, consisting of a material different from that of an underlayer, on the underlayer with a small thickness is obtained. This nitride-based semiconductor element comprises a plurality of mask layers formed at a prescribed interval to be in contact with the upper surface of the underlayer while partially exposing the underlayer and the nitride-based semiconductor layer, formed on the upper surface of the underlayer and the mask layers, consisting of the material different from that of the underlayer. The minimum distance between adjacent mask layers is smaller than the width of an exposed part of the underlayer located between the adjacent mask layers.

Abstract: A nitride-based semiconductor element having excellent element characteristics is obtained by obtaining a nitride-based semiconductor layer having excellent crystallinity without performing a long-time etching process. This nitride-based semiconductor element comprises a mask layer, having a recess portion, formed on a substantially flat upper surface of an underlayer to partially expose the upper surface of the underlayer, a nitride-based semiconductor layer formed on the exposed part of the underlayer and the mask layer while forming a void on the recess portion of the mask layer, and a nitride-based semiconductor element layer, formed on the nitride-based semiconductor layer, having an element region.

Abstract: A nitride-based semiconductor element having superior mass productivity and excellent element characteristics is obtained. This nitride-based semiconductor element comprises a substrate comprising a surface having projection portions, a mask layer formed to be in contact with only the projection portions of the surface of the substrate, a first nitride-based semiconductor layer formed on recess portions of the substrate and the mask layer and a nitride-based semiconductor element layer, formed on the first nitride-based semiconductor layer, having an element region. Thus, the first nitride-based semiconductor layer having low dislocation density is readily formed on the projection portions of the substrate and the mask layer through the mask layer serving for selective growth.

Abstract: A method of preparing a nitride semiconductor capable of forming a nitride-based semiconductor layer having a small number of dislocations as well as a small number of crystal defects resulting from desorption with excellent crystallinity on the upper surface of a substrate through a small number of growth steps is proposed. The method of preparing a nitride-based semiconductor comprises steps of forming a mask layer on the upper surface of a substrate to partially expose the upper surface of the substrate, forming a buffer layer on the exposed part of the upper surface of the substrate and the upper surface of the mask layer and thereafter growing a nitride-based semiconductor layer. Thus, the outermost growth surface of the nitride-based semiconductor layer laterally grown on the mask layer does not come into contact with the mask layer.

Abstract: A method of manufacturing a light emitting device, including the steps of: forming an active layer composed of a compound semiconductor containing indium by a vapor phase growth method; and forming a cap layer composed of a compound semiconductor on said active layer by a vapor phase growth method at a growth temperature approximately equal to or lower than a growth temperature for said active layer.

Abstract: A light emitting device includes a cladding layer composed of a III-V group nitride system semiconductor of a first conductivity type, an active layer formed on the cladding layer of the first conductivity type and composed of a III-V group nitride system semiconductor containing In, an undoped cap layer formed on the active layer and composed of a III-V group nitride system semiconductor, and a cladding layer formed on the cap layer and composed of a III-V group nitride system semiconductor of a second conductivity type.

Abstract: In a semiconductor laser device comprising an n-type cladding layer, an active layer formed on the cladding layer, a p-type cladding layer formed on the active layer, and a p-type saturable light absorbing layer provided in the p-type cladding layer, the current confinement width for confining current injected into the active layer being W, the thickness d.sub.a of the active layer, the optical confinement factor .GAMMA..sub.a of the active layer, the thickness d.sub.s of the saturable light absorbing layer, the optical confinement factor .GAMMA..sub.s of the saturable light absorbing layer, and the light spot size S on a facet of the semiconductor laser device are so set as to satisfy a predetermined relationship. The reflectivity on a light output facet is set in the range of 10 to 20%.