When the macroscopic dimension of crystalline material is continuously reduced to a very small size (of the order of few nanometer), dramatic changes in the electronic and vibrational properties of these nano-materials can be observed. Confinement in one, two or three dimensions leads to quantum structures termed as quantum well, quantum wire and quantum dot, respectively. Because of the small size, the bulk material properties change due to the quantum-mechanical effects in such dimensions. The smaller the dimension, the larger is the effective band gap. As a consequence, most of the bulk...