Unique Properties of Heat Generation in Nanoscale Systems

We study the unique properties of current-induced heat generation Q in nanostructures and its absence in macroscopic bulks. A lead−quantum dot-lead system is taken into consideration and it is found that its unique properties stem from energy quantization of the system and arise only under conditions of low temperature and weak dot-lead coupling. The relation of Q ∝I (I is the system current) fails in nanosystems, while the Q peaks align with peaks of phonon−assisted current under small bias. As a result, one can expect a large current accompanied by relatively small Q when the elastic current peak does not coincide with the phonon-assisted one, the ideal working condition for a nanostructure.