Fabrication of photonic quantum ring laser using chemically assisted ion beam etching

This article presents an etching process to fabricate a high-quality vertical facet for the photonic quantum ring (PQR) laser. The presented process uses the chemically assisted ion beam etching (CAIBE) method with a gas mixture of Ar:Cl 2 : BCl 3 =5:2:3 sccm, and uses a single-layer photoresist etch mask to reduce the process complexity of etching GaAs/AlGaAs structures for the PQR laser. The angle θ between the incident beam and the normal direction of the substrate has been adjusted to achieve a high-quality vertical facet. Distortions on the mask pattern are not transferred to the etched side wall for θ⩾25°, and a vertical facet is obtained at θ∼25°. The fabricated PQR lasers with the CAIBE process in this article show a sharp linewidth of ∼0.06 nm.