Metamorphic molecular beam epitaxy growth and selective wet etching for epitaxial layer lift-off of AlAsSb toward optical waveguides with high optical confinement

摘要

In this study, we performed epitaxial layer lift-off (ELO) of AlAs_(0.37)Sb_(0.63) layer toward realizing AlAs_(0.37)Sb_(0.63)/In_(0.75)Ga_(0.25)As systems on SiO_2. This will enable high optical confinement in the AlAs_(0.37)Sb_(0.63)/In_(0.75)Ga_(0.25)As systems to be achieved owing to the large refractive index contrast (Δn～1.6). ELO consists of two processes: the first is adhesive wafer bonding using positive photoresist and the second is two-step selective wet etching. Metamorphic molecular beam epitaxy was used to grow selective etching layers between the substrate and the AlAs_(0.37)Sb_(0.63). We confirmed that the metamorphic growth did not degrade the crystal quality and ELO was successful. Therefore, ELO improves optical confinement of AlAs_(0.37)Sb_(0.63) and will be able to improve performance of all optical intersubband switches using the AlAs_(0.37)Sb_(0.63)/In_(0.75)Ga_(0.25)As systems.