Method for fabricating a group III nitride semiconductor laser device

[0056]FIG. 3 is a vertical sectional view schematically showing the structure of the semiconductor laser device 1 of a first embodiment of the invention, and FIGS. 1 and 2 are vertical sectional views schematically showing its layer structure as observed in the middle of its fabrication. In all these figures, the dislocation-concentrated region X1 and the high-luminescence region Y1 of the substrate are also shown.

[0057] The semiconductor laser device 1 was produced in the following manner. First, on an n-type GaN substrate 100 produced as described above, a layered structure 101 was formed (FIG. 1) by forming, through successive crystal growth by MOCVD (metalorganic chemical vapor deposition), a 3 μm n-type GaN layer 102, a 40 nm n-type In0.07Ga0.93N crack prevention layer 103, a 1.2 μm n-type Al0.1Ga0.9N clad layer 104, a 0.1 μm n-type GaN optical guide layer 105, a triple quantum well active layer 106 composed of 4 nm In0.1Ga0.9N well layers and 8 nm In0.01Ga0.99N barrier layers...

[0070]FIG. 5 is a vertical sectional view schematically showing the structure of the semiconductor laser device 2 of a second embodiment of the invention, and FIG. 4 is a vertical sectional view schematically showing its layer structure in the middle of its fabrication. The semiconductor laser device 2 of this embodiment is a modified version of the semiconductor laser device 1 of the first embodiment in which dielectric films 115 are additionally formed, one in a portion of the top surface of the embedded layer 112 located right above the dislocation-concentrated region X1 of the n-type GaN substrate 100 and another in a portion of the bottom surface of the substrate 100 located right below the dislocation-concentrated region X1. The n-type GaN substrate 100 and the layered structure 101 are structured and produced in the same manner as in the first embodiment, and therefore overlapping explanations will not be repeated.

[0071] The dielectric films 115 were, after the formation of ...

[0077]FIG. 8 is a vertical sectional view schematically showing the structure of the semiconductor laser device 3 of a third embodiment of the invention, and FIGS. 6 and 7 are vertical sectional views schematically showing its layer structure in the middle of its fabrication. The semiconductor laser device 3 of this embodiment is a modified version of the semiconductor laser device 1 of the first embodiment in which a dielectric film 118 is additionally formed inside the layered structure 101, in a portion thereof located right above the dislocation-concentrated region X1 of the n-type GaN substrate 100. In other respects, the n-type GaN substrate 100 is structured in the same manner as in the first embodiment.

[0078] The dielectric film 118 was formed in the middle of the formation of the ridge-formed structure. Specifically, after digging, as described earlier, the top surface of the p-type second contact layer 111 down to the middle of the p-type clad layer 109 by dry etching to ...