A laser diode having a semiconductor layer sequence based on a nitride compound semiconductor material includes an n-type cladding layer, a first waveguide layer, a second waveguide layer and an active layer, and a p-type cladding layer including a first partial layer and a second partial layer, wherein the first partial layer includes Al.sub.x1Ga.sub.1-x1N with 0x11 or Al.sub.x1In.sub.y1Ga.sub.1-x1-y1N with 0x11, 0y1<1 and x1+y11, the aluminum content x1 decreases in a direction pointing away from the active layer so that the aluminum content has a maximum value x1.sub.max and a minimum value x1.sub.minx1.sub.max, and the second partial layer includes Al.sub.x2Ga.sub.1-x2N with 0x2x1.sub.min or Al.sub.x2In.sub.y2Ga.sub.1-x2-y2N with 0x2x1.sub.min, 0y2<1 and x2+y21.

A semiconductor light-emitting element includes: an n-type cladding layer formed of a nitride semiconductor; an active layer which is arranged above the n-type cladding layer and formed of a nitride semiconductor; a p-type cladding layer arranged above the active layer and formed of a nitride semiconductor; and a p-side electrode arranged above the p-type cladding layer, wherein the p-type cladding layer contains hydrogen, and a first concentration of the hydrogen at a center of the p-type cladding layer in a region below the p-side electrode is lower than a second concentration of the hydrogen at a position located on a side closer to an outer edge than to the center in the region below the p-side electrode.

An optoelectronic semiconductor device includes a semiconductor body in which an active layer configured to generate or detect electromagnetic radiation, a first interlayer and a p-conducting contact layer are formed, and a connection layer applied to the semiconductor body, wherein the contact layer is disposed between the first interlayer and the connection layer and adjoins the connection layer, the active layer is arranged on a side of the first interlayer remote from the contact layer, the first interlayer and the contact layer are based on a nitride compound semiconductor, the contact layer is doped with a p-dopant, the contact layer has a thickness of at most 50 nm, and the contact layer includes a lower aluminum content than the first interlayer.

Provided is an optical semiconductor device including a laminate structural body 20 in which an n-type compound semiconductor layer 21, an active layer 23, and a p-type compound semiconductor layer 22 are laminated in this order. The active layer 23 includes a multiquantum well structure including a tunnel barrier layer 33, and a compositional variation of a well layer 31.sub.2 adjacent to the p-type compound semiconductor layer 22 is greater than a compositional variation of another well layer 31.sub.1. Band gap energy of the well layer 31.sub.2 adjacent to the p-type compound semiconductor layer 22 is smaller than band gap energy of the other well layer 31.sub.1. A thickness of the well layer 31.sub.2 adjacent to the p-type compound semiconductor layer 22 is greater than a thickness of the other well layer 31.sub.1.

A nitride semiconductor laser device includes an n-type semiconductor layer, an active layer, and a p-type semiconductor layer which are formed in this order on a nitride semiconductor substrate, and by using crystal stress in the n-type semiconductor layer, the laser device is allowed to have two or more light-emitting points emitting light with different peak wavelengths in the active layer. A method for producing a nitride semiconductor laser device includes a step of forming an n-type semiconductor layer on a nitride semiconductor substrate, a step of forming an active layer on the n-type semiconductor layer, and a step of forming a p-type semiconductor layer on the active layer. In the step of forming the n-type semiconductor layer, the n-type semiconductor layer is formed so as to produce a stress difference in a portion of the n-type semiconductor layer.

A surface emitting laser includes: a semiconductor layer containing a nitride semiconductor, and including a first semiconductor layer, an active layer, and a second semiconductor layer that are stacked in this order, in which the semiconductor layer includes a light emitting region; and a first light reflecting layer and a second light reflecting layer that are opposed to each other with the semiconductor layer being disposed therebetween. The first semiconductor layer has a high dislocation portion disposed outside the light emitting region. The high dislocation portion has an average dislocation density higher than an average dislocation density of the light emitting region.

A method of fabricating a gain medium includes growing a p-type layer doped with zinc on a substrate, growing an undoped layer including one or both of InP or InGaAsP on the p-type layer, growing a region that includes multiple quantum wells (MQWs) on the undoped layer, and growing an n-type layer on the region. The undoped layer has a thickness that is sufficient to prevent Zn diffusion from the p-type layer into the region during subsequent growth or wafer fabrication steps.

An AlGaInPAs-based semiconductor laser device includes a substrate, an n-type clad layer, an n-type guide layer, an active layer, a p-type guide layer composed of AlGaInP containing Mg as a dopant, a p-type clad layer composed of AlInP containing Mg as a dopant, and a p-type cap layer composed of GaAs. Further, the semiconductor laser device has, between the p-type guide layer and the p-type clad layer, a Mg-atomic concentration peak which suppresses inflow of electrons, moving from the n-type clad layer to the active layer, into the p-type guide layer or the p-type clad layer.

A gallium and nitrogen containing laser diode device. The device has a gallium and nitrogen containing substrate material comprising a surface region. The surface region is configured on either a non-polar crystal orientation or a semi-polar crystal orientation. The device has a recessed region formed within a second region of the substrate material, the second region being between a first region and a third region. The recessed region is configured to block a plurality of defects from migrating from the first region to the third region. The device has an epitaxially formed gallium and nitrogen containing region formed overlying the third region. The epitaxially formed gallium and nitrogen containing region is substantially free from defects migrating from the first region and an active region formed overlying the third region.

An optical device has a gallium and nitrogen containing substrate including a surface region and a strain control region, the strain control region being configured to maintain a quantum well region within a predetermined strain state. The device also has a plurality of quantum well regions overlying the strain control region.