Planar disorder- and native-oxide-defined photopumped AlAs–GaAs superlattice minidisk lasers

Data are presented on the photopumped laser operation of planar AlAs–GaAs superlattice (SL) minidisk lasers. The SL minidisk (70 Å AlAs, 30 Å GaAs; 100 periods; ∼37 μm diameter) is defined by impurity-induced layer disordering (IILD), followed by wet oxidation (N2+H2O vapor, 400 °C which surrounds the minidisk with a low-refractive-index AlGaAs oxide. The planar minidisks exhibit laser operation at λ∼7540 Å, with wider mode separation (Δλ∼13 Å) than disks defined by only IILD (a smaller refractive index step) and cleaved sample edges. The mode separation of Δλ∼13 Å corresponds to disk modes that utilize the perimeter of the oxide-defined disks. In the fabrication of the SL minidisks, IILD forms a structural and doping difference beyond the disk perimeter that acts, in effect, as a p–n junction during etching or wet oxidation. Etch profiles are shown demonstrating this behavior.