抄録
We describe photoluminescence imaging spectroscopy based on a near-field scanning optical microscope (NSOM). By refining the design and fabrication method of a NSOM probe, the spatial resolution has been remarkably improved as high as 30nm. The resolution allows us to map out the wavefunction of an exciton confined in a large quantum dot. In this article we study a variety of quantum confinement structures: interface fluctuation GaAs quantum dots (QDs) with a typical size of 100nm, electrostatic field induced GaAs QDs of 500nm, and nitrogen clustering induced quantum confinement structures in GaNAs ranging from smaller than 30nm (the spatial resolution) to several hundreds nm. In the case of the interface QDs, the quantum energy spacing exceeds the thermal energy and therefore the wavefunctions of individual exciton states are success-fully visualized. In the other cases, since the interlevel energy spacings are rather small, we discuss our resultsin terms of local densities of states.
