The quality of thermoelectric materials is given by ZT figure of merit which is a function of Seebeck coefficient (S), electrical conductivity (), temperature (T), phonon and electron thermal conductivity(kp and ke). If Seebeck coefficient is a function of the material size/critical dimension x such that;

Indicate what is the value of ZT at x0 limit (circle out your answer)?and explain why?

ZT=0, ZT=, ; ZT=S0,