Quantum Dots and Quantum Wires with High Optical Quality by Implantation-Induced Intermixing

The use of a near-surface quantum well as a starting material in conjunction with a low implantation energy is demonstrated to be a key parameter for the realization of homogeneous nanostructures for optical applications by implantation-induced intermixing. Using this technique we have realized GaAs/AlGaAs quantum wires with wire widths down to 45 nm and quantum dots with diameters ranging from 400 to 70 nm. The optical properties of the structures have been studied by low-temperature photoluminescence and photoluminescence excitation spectroscopy. In photoluminescence the structures show a high intensity, and from the observed increasing blue shift with decreasing size, steep confining potentials are concluded. The excitation spectra clearly demonstrate the advantage of the near-surface quantum wells by the reduction of level broadening compared to previous results on quantum wires.