Semiconductor laser having double heterostructure and method of producing same

A method of producing a semiconductor laser comprising the steps of:

• (a) patterning a dielectric layer which is formed on a main surface of a substrate into a stripe;
• (b) forming a stripe of a first mesa by making a mesa etching of the substrate using the stripe of the dielectric layer as a mask, said stripe of the first mesa having a top surface and a sloping surface;
• (c) removing eaves of the dielectric layer which is used as the mask in said step (b) by an etching;
• (d) forming a buried layer by a metal organic vapor phase epitaxy (MOVPE) using the remaining dielectric layer as a mask so that the buried layer is formed on said substrate excluding the top surface of the stripe of the first mesa and the sloping surface of the stripe of the first mesa is covered a sloping surface part of said buried layer, said step (d) being carried out under conditions such that the growth rate of the buried layer on the sloping surface of the stripe of the first mesa is slower than that at other parts of the substrate, said top surface of the stripe of the first mesa forming a stripe of a second mesa together with the sloping surface of said buried layer, said stripe of the second mesa having a smaller inclination than said stripe of the first mesa;
• (e) removing the dielectric layer by an etching;
• and
• (f) forming a double heterostructure made up of a plurality of semiconductor layers on the stripe of the second mesa by a metal organic vapor phase epitaxy (MOVPE), said double heterostructure including an active layer and first and second cladding layers which sandwich the active layer, and is provided along the main face of the first mesa and along the sloping surface of the second mesa.

A method of producing a semiconductor laser comprising the steps of:

• (a) forming on a substrate a mask having a stripe opening which extends in a <110>
• direction of the substrate, said substrate being made of a compound semiconductor of a first conductor type;
• (b) forming a stripe projection part on the substrate which is exposed within the stripe opening by a metal organic vapor phase epitaxy (MOVPE), said stripe projection part having one of a triangular and a trapezoidal cross section with a (111)B face as its sloping surface and being made of a compound semiconductor;
• (c) forming a blocking layer on the substrate by a metal organic vapor phase epitaxy (MOVPE) so as to cover the (111)B face under a predetermined condition such that a growth rate of the blocking layer on the sloping surface of the stripe projection part is slower than that at other parts of the substrate;
• and
• (d) forming a stripe part which acts as a wave guide and a bent part provided on both sides of the stripe part for trapping light by successively growing a first cladding layer, an active layer and a second cladding layer, said stripe part being formed above said stripe projection part, said bent part having a (311)B face as its sloping surface, said first and second cladding layers being respectively made of mutually opposite first and second conductor types.