Theoretical Study on Thermoelectric Properties of Ge Nanowires Based on Electronic Band Structures

Abstract

Theoretical studies on the thermoelectric properties of Ge nanowires (NWs) in terms of the Seebeck coefficient, electrical conductance, and power factor are carried out under different combinations of parameters. As orientation affects power factor, [100] Ge NWs have better performance than NWs along [111] and [110] in general. For extremely small (1-nm) NWs, the effect of cross-sectional shape also plays an important role on the thermoelectric properties of Ge NWs due to quantum confinement effects. The thermoelectric properties vary strongly depending on the band structure of the Ge NWs of different sizes, cross-sectional shapes, and orientations. Comparing the results between 1-nm triangular Ge and Si NWs in terms of power factor, p-type Ge NWs outperform Si NWs, while n-type Si NWs outperform Ge NWs due to the higher numbers of subband valleys contributing to electron transport.