Nitride semiconductor substrate production method thereof and semiconductor optical device using the same

A method of producing a nitride semiconductor substrate comprising the steps of:

• performing a selective growth process to form a plurality of seed crystals made of AlxGa1−x−yInyN (0≦x≦0.1, 0≦y≦0.5) on a first semiconductor layer made of (0001) face AlxGa1−x−yInyN (0≦x≦0.1, 0≦y≦0.5), in such a manner said seed crystals are provide, respectively, with slant surfaces, and arranged in an equally-spaced stripe pattern;
• depositing an intermediate layer made of AlaGa1−a−bInbN (0.1≦a≦1, 0≦b≦1), on said seed crystals at low temperature of 300 to 800° C.;
• and
• growing a second semiconductor layer made of AlaGa1−a−bInbN (0.1≦a≦1, 0≦b≦1), on said intermediate layer until said second semiconductor layer has a flat surface.

A nitride semiconductor substrate comprising:

• a single-crystal substrate having equally-spaced stripe-shaped grooves;
• a plurality of seed crystals each made of AlxGa1−x−yInyN (0≦x≦0.1, 0≦y≦0.5) and formed on the convex portions of said single-crystal substrate to have a slant surface;
• an intermediate layer made of AlaGa1−a−bInbN (0.1≦a≦1, 0≦b≦1), and deposited on said seed crystals at low temperature of 300 to 800° C.;
• and
• a second semiconductor layer made of AlaGa1−a−bInbN (0.1≦a≦1, 0≦b≦1), and formed on said intermediate layer to have a flat surface.

A method of producing a nitride semiconductor substrate comprising the steps of:

• forming a plurality of seed crystals each made of AlxGa1−x−yInyN (0≦x≦0.1, 0≦y≦0.5), on a single-crystal substrate having equally-spaced stripe-shaped grooves, in an equally-spaced stripe pattern;
• depositing an intermediate layer made of AlaGa1−a−bInbN (0.1≦a≦1, 0≦b≦1), on said seed crystals at low temperature of 300 to 800° C.;
• and
• growing a semiconductor layer made of AlaGa1−a−bInbN (0.1≦a≦1, 0≦b≦1), on said intermediate layer until said semiconductor layer has a flat surface.