Shapes of nanomaterials

Nanomaterials are classified as quantum wells, quantum wires and quantum dots. In a three dimensional structure, if one dimension, say thickness, is of nanosize, then the structure is called quantum well. If two dimensions are of nanosize, then it is called a quantum wire and if all the three dimensions are of nanosize, then it is called quantum dot. The word quantum is associated with the structures because the properties exhibited by them are described by quantum mechanics. The density of states for the various quantum structures can be explained. For quantum dots, permitted energy values are almost discrete. But chance for a slight broadening exists due to the size effect. In a quantum wire, density of states has peaks. For a quantum well, density of states varies as a step function.