Patterned Quantum Dot Molecule Laser Fabricated by Electron Beam Lithography and Wet Chemical Etching

We report on the fabrication and characterization of an edge-emitting semiconductor laser with a gain medium consisting of two layers of patterned, self-aligned, vertically coupled quantum dots (QDs) using a wet-etching and regrowth technique. A threshold current density of 300 A/cm
²
is demonstrated at 77 K. The presence of emission from QD excited states in both the spontaneous emission and laser spectra indicates 3-D quantum confinement in QDs fabricated using this technique.