Effects of impurity-band conduction on thermoelectric properties of lightly doped p-type CoSb3

Experimental data on the thermoelectric properties of lightly doped p-type CoSb3 reported by Mandrus et al. [Phys. Rev. B 52, 4926 (1995)], Arushanov et al. [Phys. Rev. B 56, 1911 (1997)], and Dyck et al. [Phys. Rev. B 65, 115204 (2002)] have been analyzed, incorporating both the impurity-band conduction and the nonparabolicity of the valence band. The concentrations of a resonant acceptor, a deep acceptor, and a compensating donor level have been considerably corrected from those obtained in the original studies by Arushanov et al. and Dyck et al. The impurity-band conduction in the deep acceptor level has been proved to be the dominant conduction mechanism at low temperatures in the sample of Dyck et al. while that in the resonant acceptor level has been proved to be the dominant one in the other samples. Especially, the impurity-band conduction has been proved to be predominant up to as high as 400 K in the sample of Mandrus et al. As a result of incorporating the effects of both the impurity-band cond...