InGaAsP/InP 1.55-μm lasers with chemically assisted ion beam-etched facets

Abstract

Chemically assisted ion beam etching (CAIBE) involving an Ar ion beam and a halogen ambient gas (Cl₂, IBr₃) has been used to etch high-quality laser facets for InGaAsP/InP bulk lasers (1.55 μm). We achieved eich rates of 40.0–75.0 nm min⁻¹ at substrate temperatures between-5 and +10°C. These low temperatures have allowed us to utilize UV-baked photoresists as well as PMMA as etch masks, facilitating very simple process development. Higher substrate temperatures (50 to 120°C) yield still higher etch rates, but at the expense of severely 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 higher temperature range; low temperatures yield stoichiometric surfaces.