The figures of merit of different GALs as a function of the Fermi energy are compared in Fig. 3.18. IsoTri has the highest , because it has the lowest lattice thermal conductance and one of the largest Seebeck coefficients. At room temperature, the factor has significant values only in the range of around the Fermi level. Under the condition , holes have no contribution to the total electrical current. A large value of the Seebeck coefficient is therefore obtained.

In our work we did not consider the passivation of dangling bonds at the edges. However, it has been shown that hydrogen passivation of dangling bonds results in further reduction of the thermal conductance [70]. Therefore, a higher for GALs can be obtained by edge passivation.