TABLE OF CONTENTS The spherical, semi-conductor nanocrystal atoms, ranging in size from 2 to 50 nm (nanometers), also called quantum boxes or quantum dots, have intermediary properties between those of a molecule and a solid. The electron s energy is no longer spread out in bands of energy as in an ordinary semi-conductor, but in discrete, quantified levels as in an atom or in a molecule. The distribution of energy on these levels is relative to the size of the crystal. It results in the fact that the wavelength from the light source, which corresponds to the relative recombination of these pseudo atoms under excitation, can be adjusted in the visible domain. This technique is largely used in the medical world where nanocrystals are used as fluorescent markers. We find a similar explanation for quantum well lasers.
