Patent ID: 8633041
Filing Date: 2014-01-21
Classification: B82Y,H01S

Abstract:
1. A method for manufacturing a quantum cascade laser comprising the steps of: forming a semiconductor stacked structure on a semiconductor substrate having a principal surface, the semiconductor stacked structure including a first semiconductor region which includes an Al-containing III-V group compound semiconductor layer and a core layer for the quantum cascade laser and a second semiconductor region which is disposed on the first semiconductor region and which includes an Al-free III-V group compound semiconductor layer; forming an etching mask on the second semiconductor region of the semiconductor stacked structure, the etching mask having a striped pattern extending in the <0-11> direction; forming a semiconductor mesa structure having a mesa shape in cross section by etching the first and second semiconductor regions using the etching mask; forming an insulating layer over a top portion and side surfaces of the semiconductor mesa structure and the first semiconductor region; forming an opening in a portion of the insulating layer that is disposed on the top portion of the semiconductor mesa structure; and forming an electrode over the inside of the opening of the insulating layer, the top portion and side surfaces of the semiconductor mesa structure, and the first semiconductor region, wherein the step of forming the semiconductor mesa structure includes a first etching sub-step and a second etching sub-step, in the first etching sub-step, side surfaces of the second semiconductor region are shaped by selectively etching the second semiconductor region by reactive ion etching using the etching mask until a surface of the first semiconductor region is exposed, in the second etching sub-step, the side surfaces of the second semiconductor region and the first semiconductor region are etched by wet etching using the etching mask, and the etching rate of the Al-containing III-V group compound semiconductor layer is less than the etching rate of the Al-free III-V group compound semiconductor layer during reactive ion etching in the first etching sub-step.