Abstract
This study focuses on investigating the structure of silicon nanowires and the possibility of elevating the Figure of Merit with the addition of magnetic defects. This initiative will provide a chance to have an advantage over the most popular electrical materials, such as 〖Bi〗_2 〖Te〗_3 which has a ZT around 1.0. In addition, with nanowires, the price can be lowered and the supply of materials can be guaranteed not to be in short. Furthermore, the structure of silicon is compatible with the present semiconductor technology, and it will be great potential in marketing. Some factors which influence the efficiency of thermoelectric materials includes; electrical conductivity, Seebeck coefficient, and thermal conductivity, among others. All of these properties are dependent on the density of states (DOS) and phonon dispersion relations. In addition, these material properties will also vary with different sizes and, inevitably with the magnetic defects, added on purpose. In this research, we use the method of density functional theory (DFT) to build silicon nanowire structures. Then, we try to change the structure and add magnetism effects to find the influence that this conveys in the DOS and band structures. On the other hand, we determine the phonon dispersion relations and the phonon density of states from the density functional perturbation theory (DFPT). After the previously mentioned simulation results have been obtained, we input these previously calculated properties into the Boltzmann transport equation to obtain key properties of Figure of Merit. Afterwards, we can compare ZT values obtained from the different silicon nanowire structures. In the results, we can see that the Fermi level changed in the DOS with the addition of magnetism. This phenomenon leads to an improvement of electric conductivity, and the defects we designed for the magnetism addition in nanowires reduce the thermal conductivity. In conclusion, we obtain the improvement of ZT in most of the selected magnetism silicon nanowires.