Raman Spectroscopy on Tunable GaAs Double Quantum Wells and Wires

Centre for Atom Optics and Ultrafast Spectroscopy
Swinburne University of Technology

Friday, 23 November 2007, 2.00pm, EN214, Engineering Building, Hawthorn.

Low-dimensional electron systems play an important role in technological applications in the field of microelecronics as well as in basic research on quantum-mechanical systems. A great amount of fundamental research was performed on two dimensional electron systems. Here the most famous experiment was certainly the discovery of the integer Quantum Hall effect by Klaus von Klitzing in 1980. After an introduction on semiconductor fabrication techniques I will show the investigation of electronic excitations in GaAs-Al_xGa_1-xAs double-layered quantum wire arrays with strong tunneling coupling by resonant inelastic light scattering. By applying an external electric field, the one-dimensional electron density and the symmetry of the double quantum-well (DQW) structure can be changed at the same time. Confined optical and acoustic intersubband plasmons can be identified. Due to the tunneling coupling, the energies of the acoustic intersubband plasmons exhibit a minimum for a symmetric DQW potential, whereas the energies of the confined optical plasmons are dominated by the total carrier density, and are nearly insensitive to the symmetry of the potential.

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