Thermopower and Hall Effect Measurements

Thermoelectric power is the potential gradient generated between two points or faces of a material when they are subject to a temperature differential. Typically, it is large for semiconductors, while for metals it is small and decreases with decreasing temperature, vanishing near absolute zero. A small decrease of thermopower with temperature would thus likely indicate hopping conduction, whilst a very rapid decrease and very low values (see below) for the thermopower would indicate a quasi-metallic conduction, as for instance observed for highly doped trans-P(Ac). 

6-19 Thermoelectric power (S) as a function of temperature for various Ij doping levels. Dopant concentrations are A = 0, B = 0.017, C = 0.03, and D = 0.22. After Reference [152], reproduced with permission. 

The thermoelectric power behavior of most CPs parallels that of temperature and activation energy relationships. 

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