Wet etching fabrication of photonic quantum ring laser

Abstract

We present a wet etching process to fabricate good vertical mesa structures that result in high quality (Q) factors up to 2x10(4), important for smooth sidewall cavities such as the photonic quantum ring (PQR) laser. Q factor analyses also indicate that it can be improved much more once the internal scattering from the wafer materials is minimized. We use an etching solution of H3PO4:CH3OH:H2O2 with a volume ratio of 3:1:1, and a single-layer photoresist etch mask for etching GaAs/AlGaAs structures of the PQR laser several micrometer deep. As the etching temperature is varied from 20 to 40 degreesC, the etched surface roughness decreases from 4.690 to 0.703 nm according to scanning electron microscope and atomic force microscopy studies. From the activation energy analysis for the above etching process and the temperature dependence, the etching process is shown to be reaction limited. The PQR lasers with an active diameter of 10 mum, fabricated by the wet etching process, show the spectral linewidth of 0.04 nm. Three-dimensional Rayleigh-Fabry-Perot mode spectra for the PQR laser are also reported for the angle-resolved emission modes. (C) 2004 American Institute of Physics.