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-quality 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 very simple process development. Higher substrate temperatures (50 to 120 degrees 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. [References: 11]
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