A comprehensive study of the mechanisms of heating and cooling originated by the electrical current in semiconductor devices is reported. The authors study the Peltier, Joule and Thomson phenomena self-consistently in approximation of a weak electric current. A new formulation and interpretation of the Thomson effect are offered. Along with new results, a certain attention is paid to some questions of nonequilibrium thermodynamics of thermoelectric and electrothermic phenomena, which demand some definition.

Se presenta un estudio comprensivo de los mecanismos de calentamiento y enfriamiento originados por una corriente eléctrica en un dispositivo semiconductor. Los autores analizan los efectos de Peltier, Joule y Thomson en la aproximación de corrientes eléctricas débiles. Se ofrece una nueva interpretación y formulación del efecto Thomson. Cierta atención se presta a algunas cuestiones de termodinámica fuera de equilibrio de los fenómenos termoeléctrico y electrotérmico que exigen ciertas especificaciones.

Nontraditional approach to explain the thermoelectric cooling is suggested . It is based on the Le Chatelier-Braun thermodynamic principle. New effect of cooling and heating of junction of two materials (barrierless thermoelectric cooling) is theoretically predicted, and this effect is different from the Peltier effect (barrier thermoelectric cooling). The suggested thermoelectric effect must be displayed always at the finite values of the junction surface heat conductivity eta. Barrierless thermoelectric effect occurs even in the case when the conducting materials are identical with the same Peltier coefficients. It is shown that both barrier and barrierless thermoelectric cooling effects always exist simultaneously in the general case. The reasons proving reversibility of the thermoelectric cooling process are resulted.

The general boundary conditions for the thermal diffusion equation are obtained. It is shown that in the general case of a nonstationary photothermal process these boundary conditions must include both the surface thermal conductivity and surface thermal capacity. One more parameter, the surface capacity thermal impedance, appears in the boundary conditions when the photothermal process is the thermal wave propagation.