Theoretical Study of Electronic and Thermoelectric Properties of Ultra-Thin Silicene and Germanene

Abstract

In this study, we used the Non-Equilibrium Green Function (NEGF) and Density Functional Theory (DFT) to analyze the nanoscale electronic properties of silicene and germanene structures, the band structure and Density of State (DOS) for the unit cell of silicene and germanene are found that the energy gap is (0 eV) in both. A comparison was made between silicene and germanene in terms of electrical and thermal properties, by calculating the transmission coefficient T(E) for silicene patterns (Si1, Si2, Si3, and Si4) and germanene patterns (Ge1, Ge2, Ge3, and Ge4). The results show that T(E) decreases with increasing etching depth, which also leads to a decrease in electronic conductivity. Moreover, the value of the Seebeck coefficient (S) increases with increasing drilling depth, and also the sign of S varies from a positive value for (Si1, Si4, Ge1, Ge2, Ge4) to a negative value for (Si2, Si3, Ge3) at Fermi level (Ef) equal to (0 eV). The highest value of the figure of merit is about (1.8) for the Ge4 structure.