Laser beam heating and transformation of a GaAs-AlAs multiple-quantum-well structure

Laser beam heating and processing of a GaAs-AlAs superlattice was studied using quantum-well luminescence as a probe. Using stationary cw laser heating, it was found that it was impossible to obtain a GaAlAs alloy without destruction of the sample. Luminescent properties of the material were significantly altered at a threshold ∼24 kW/cm2, corresponding to a temperature ∼500 K inside the laser spot. Low temperature measurements showed that the energies of the quantum-well transitions were shifted. The room temperature luminescence of this ‘‘new phase’’ was quenched, allowing the formation of ‘‘written’’ dark patterns on a bright infrared luminescence background of the original superlattice using the laser beam.