Aluminum-oxide thermally grown into high Al-concentration Al_xGa_1-xAs layers has recently been studied extensively. The material shows electrical and optical properties that make it useful in a semiconductor laser fabrication process where it can provide electrical isolation and optical guiding, as well as simplify the fabrication and integration process considerably. We use this thermal oxide to produce GaAs/AlGaAs semiconductor lasers that can be integrated with other devices. The GaAs cap- layer is masked with photoresist and the exposed GaAs areas are etched away, leaving a GaAs oxidation mask on the AlGaAs upper cladding layer. Using N₂ carrier gas saturated with H₂O vapor, the uncovered Al_0.8Ga_0.2As material is converted into a stable aluminum-oxide at temperatures around 450 degree(s)C. Due to the near-isotropic oxidation an `ellipsoidal' diffusion front is created, which is in strong contrast to the well-known mesa cross-section in conventional dry-etched ridge-waveguides but is more similar to e.g. wet-etched buried heterostruture lasers.

Date Published: 28 July 1994
PDF: 9 pages
Proc. SPIE 2213, Nanofabrication Technologies and Device Integration, (28 July 1994); doi: 10.1117/12.180962

Published in SPIE Proceedings Vol. 2213:
Nanofabrication Technologies and Device Integration
Wolfgang Karthe, Editor(s)