Anomalously small resistivity and thermopower of strongly compensated semiconductors and topological insulators

作者：Chen Tianran^*; Shklovskii B I

来源：Physical Review B, 2013, 87(16): 165119.

DOI：10.1103/PhysRevB.87.165119

In the recent paper, we explained why the maximum bulk resistivity of topological insulators (TIs) such as Bi2Se3 is so small [B. Skinner, T. Chen, and B. I. Shklovskii, Phys. Rev. Lett. 109, 176801 (2012)]. Using the model of completely compensated semiconductor we showed that when the Fermi level is pinned in the middle of the gap the activation energy of resistivity is Delta = 0.3(E-g/2), where E-g is the semiconductor gap. In this paper, we consider a strongly compensated n-type semiconductor. We find the position of the Fermi level mu calculated from the bottom of the conduction band E-c and the activation energy of resistivity Delta as a function of compensation K, and show that Delta = 0.3(E-c - mu) holds at any 0 < 1 - K <= 1. In the same range of relatively high temperatures, the Peltier energy (heat) Pi is even smaller: Pi similar or equal to Delta/2 = 0.15(E-c - mu). We also show that at low temperatures, the activated conductivity crosses over to variable range hopping (VRH) and find the characteristic temperature of VRH, T-ES, as a function of K. DOI: 10.1103/PhysRevB.87.165119

• 出版日期2013-4-15