Thermopower in Thin-Film Copper—Constantan Couples

Abstract
The thickness dependence of the thermal emf of thin‐film copper—constantan thermocouples at room temperature and above shows nearly bulklike behavior when the thickness of both elements comprising the thermocouple is greater than ∼1200 Å. The thermal response time of the thermocouples as measured with a pulsed laser beam heating source is less than 10‐6 sec. The thickness‐dependent contribution to the thermopower of copper films is deduced from the thermal emf data on thermocouples formed with a thick constantan film and compared with the size‐effect theory based on the free‐electron model. The marked thickness dependence observed yields anomalously high dependence (an order‐of‐magnitude higher) of the mean free path on the energy of electrons. This result is tentatively ascribed to the thermopower behavior of a transition layer formed by diffusion of the two components of the thermocouples.

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