SPECTROSCOPY OF QUANTUM DOTS AND ANTIDOTS

The remarkable progress of submicron technology has made it possible to realize man-made low-dimensional electronic systems. Starting from two-dimensional electronic systems (2DES) in semiconductor heterostructures the electrons are further confined by lateral potentials acting on a submicron scale. This induces quantum confined energy states such that, for wires, a set of one-dimensional subbands with free dispersion in only one direction is formed or, for dots, artificial "atoms" with a totally discrete energy spectrum are obtained. A reversed structure with respect to quantum dots are "antidots" where geometrical holes are "punched" into an originally 2DES. These low-dimensional systems exhibit unique properties. In this review we would like to discuss some recent results on far-infrared excitations in quantum dots and antidots.