Enhancement of Thermoelectric Efficiency by Uniaxial Tensile Stress in n-type GaAs Nanowires

The thermoelectric power-factor (PF) and efficiency (ZT) of GaAs nanowires (NWs) can be improved by (i) choosing a proper wire growth and channel orientation, (ii) by applying uniaxial tensile stress, and (iii) suitable wire cross-section size. In this work we study the impact of these three factors on the PF and the ZT. Tensile stress, channel direction and cross-section size allows bandstructure engineering to tune the electronic conductance (G) and the Seebeck coefficient (S). [110] GaAs NWs grown on (111) surface provide maximum PF (3X) and ZT (1.3X) compared to [100]/(100) NWs, which can be attributed to the G enhancement induced by the L valley contribution under strain