Models for the thermal diode open-circuit voltage

We have developed a nonlocal generalization of the Onsager current relation to study the enhancement of the open-circuit voltage observed in InSb thermal diode experiments. Numerical solutions are obtained by brute force. Nonlocal effects produce an apparent enhancement of the thermopower in regions where the doping concentration changes. Models show voltage drops associated with npn barriers similar to experiment below 350 K, but are not as great as experimental results at high temperature near 600 K. This is thought to be due to thermal drops at the barrier not accounted for so far.