Semiconductor laser and method for manufacturing the same

A method for manufacturing a semiconductor laser, comprising:

• forming at least a first conduction-type semiconductor layer, an active layer, and a second conduction-type semiconductor layer on a first conduction-type semiconductor substrate with (100) as a primary face;
• etching the second conduction-type semiconductor layer in a stripe shape in the <011> direction to form at least four recessed portions, thereby forming a central ridge portion and two or more lateral ridge portions;
• forming an insulation layer with a lower refractive index than the second conduction-type cladding layer over the surface;
• removing the insulation film on the second conduction-type semiconductor layer by etching so as to expose the upper surface of the second conduction-type semiconductor layer formed at the central ridge portion and thereby form the remaining insulation film into a pair of stripes disposed respectively in the regions from the side surface of the second conduction-type cladding layer on both side portions of the central ridge portion toward the outside;
• and
• forming an electrode that forms an ohmic junction with the second conduction-type semiconductor layer.

A method for manufacturing a semiconductor layer having a central ridge portion constituting a ridge-type current confinement portion and at least two lateral ridge portions positioned on both sides of the central ridge portion, the method comprising:

• forming a first conduction-type cladding layer, an active layer, a second conduction-type cladding layer, a second conduction-type contact layer, and a first conduction-type current blocking layer on a first conduction-type semiconductor substrate with (100) as a primary face;
• etching the first conduction-type current blocking layer in a stripe shape in the <011> direction to leave the lateral ridge portions;
• etching the exposed second conduction-type contact layer in a stripe shape in the <011> direction, leaving the central ridge portion and the lateral ridge portions;
• using the second conduction-type contact layer as a mask and etching the second conduction-type cladding layer in a stripe shape in the <011> direction;
• forming an insulation film with a lower refractive index than the second conduction-type cladding layer over the surface;
• removing the insulation film on the central ridge portion and the lateral ridge portions by etching;
• and
• forming an electrode that forms an ohmic junction with the second conduction-type contact layer.

A method for manufacturing a semiconductor laser having a central ridge portion constituting a ridge-type current confinement portion and at least two lateral ridge portions positioned on both sides of the central ridge portion, the method comprising:

• forming a first conduction-type cladding layer, an active layer, a second conduction-type cladding layer, a second conduction-type contact layer, and a first conduction-type or undoped semiconductor layer on a first conduction-type semiconductor substrate with (100) as a primary face;
• etching the semiconductor layer in a stripe shape in the <011> direction, leaving the lateral ridge portions;
• etching the exposed second conduction-type contact layer in a stripe shape in the <011> direction to leave the central ridge portion and the lateral ridge portions;
• using the second conduction-type contact layer as a mask and etching the second conduction-type cladding layer in a stripe shape in the <011> direction;
• forming an insulation film with a lower refractive index than the second conduction-type cladding layer over the surface;
• removing the insulation film on the central ridge portion and the lateral ridge portions by etching;
• providing high resistance by ion implantation after forming a mask for ion implantation that covers at least the central ridge portion, and
• forming an electrode that forms an ohmic junction with the second conduction-type contact layer.