PHOTOLUMINESCENCE FROM GAAS ALGAAS QUANTUM WIRES AND QUANTUM DOTS/

Quantum wires and dots have been fabricated by local interdiffusion of undoped GaAs/AlGaAs quantum well structures. Thermal interdiffusion i s induced by a focused laser beam. In periodic arrays of quantum wires the photoluminescence (PL) splitts into several predominant lines whi ch are separated by up to about 8meV. These PL lines are attributed to the quantum number conserving optical transitions between 1-dimension al electron and hole levels. Sample inhomogeneities cause broadening o f the lines. The transition peaks shift in energy scanning a PL probe with a size of only one micron across the structures. Inhomogeneous li ne broadening is eliminated by investigation of a single quantum dot. A series of dots with different size show a systematic behaviour of PL blueshift and PL peak splitting. The main peaks in PL and PL excitati on (PLE) spectra coincide well in energy and they are separated by up to about 10meV. These peaks can be described by the allowed transition s between OD single particle levels within the nearly parabolic potent ials caused by interdiffusion. Detailed calculations of excitonic stat es within the structures result in similar optical spectra. The observ ation of intense luminescence from excited dot levels indicates a slow ing down of the energy relaxation of carriers. This is in good agreeme nt with calculated LA phonon emission rates of carriers in OD systems. At low excitation density PL lines from a single quantum dot reveal w idths of less than 0.5meV.