INGAASP INP 1.55-MU-M LASERS WITH CHEMICALLY ASSISTED ION BEAM-ETCHEDFACETS/

Chemically assisted ion beam etching (CAIBE) involving an Ar ion beam and a halogen ambient gas (Cl-2, IBr3) has been used to etch high-qual ity laser facets for InGaAsP/lnP bulk lasers (1.55 mu m). We achieved etch rates of 40.0-75.0 nm min(-1) at substrate temperatures between - 5 and +10 degrees C. These low temperatures have allowed us to utilize UV-baked photoresists as well as PMMA as etch masks, facilitating ver y simple process development. Higher substrate temperatures (50 to 120 degrees C) yield still higher etch rates, but at the expense of sever ely degraded surface morphologies. Angle resolved x-ray photoelectron spectroscopy (XPS) was investigated for observing etched InP surfaces. A disproportioned surface has been detected after etching in the high er temperature range; low temperatures yield stoichiometric surfaces.