Abstract: A semiconductor laser is formed of gallium nitride series compound semiconductor and has a double hetero structure including an MQW (multiple quantum well) active layer held between p-type and n-type AlGaN clad layers. The double hetero structure is held between p-type and n-type contact layers. An InGaN optical absorption layer having an optical absorption coefficient larger than the clad layer which has the same conductivity type as the contact layer and is formed adjacent to the contact layer is formed in at least one of the contact layers and an InAlGaN optical guided mode control layer (layer of small refractive index) having an refractive index smaller than the clad layer is formed on the exterior of the optical absorption layer.

Abstract: Disclosed is a gallium nitride-based compound semiconductor device, including a laminate film consisting of a plurality of layers stacked one upon the other to form a pn-junction and formed of InGaAlN. The semiconductor device also includes an n-side electrode and a p-side electrode to supply current to the pn-junction. Further included is a heat generation structure formed within the laminate film. The heat generation structure includes a low resistivity portion having a relatively low resistivity and a high resistivity portion having a relatively high resistivity and positioned adjacent to the low resistivity portion. The low resistivity portion and the high resistivity portion are formed within a single layer, differ from each other in carrier concentration, and formed by introducing an impurity into the single layer in a different dose such that the low resistivity portion is positioned closer to the p-side electrode than the high resistivity portion.