The thermal photo-electric phenomenon in semi-conductors
On illuminating homogeneous samples cut from single crystals of germanium an emf was observed when a thermal current flowed through them. This phenomenon was called a “thermal photo-electric phenomenon” and is caused by the fact that illumination changes the thermal emf of the semi-conductor. Using equations from the thermodynamics of irreversible processes a theory of this phenomenon was elaborated. Its conclusions are in agreement with preliminary measurements. It is shown that the measurement of a thermal photo emf renders possible the determination of Q 1 * +Q 2 * where Q 1 * , Q 2 * are the mean kinetic energies transferred by the electron and hole respectively. The type of scattering of the current carriers can be judged from the magnitude of Q 1 * +Q 2 * .
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