An enhanced thermoelectric property of 1-D silicon atomic wire: An ab-initio study

Abstract

The band structure calculation was performed using the Full Potential Linearized Augmented Plane Wave Method (FP-LAPW) within a frame work of Density Functional Theory (DFT). We have observed a band gap in cubic bulk Silicon where as a Silicon atomic chain shows a Dirac cone like features along the delta-symmetry, approx 3.0 eV above Fermi energy (EF). An indirect band gap of about 1.16 eV is observed in case of bulk Si crystal. The narrow band gap has been shifted in case of Si-atomic wire to the conduction region. The shifted band gap in Si-nano structure indicates the semi-metal type behaviour, thereby increasing its electrical conductivity. The Boltzmann semi-classical transport theory is used to calculate the thermoelectric properties. The ZT value of Si atomic chain is approx 1.55 at 120 K, which is higher than the experimental value, 1.2.