Thermionic and tunneling cooling thermodynamics

We unambiguously identify and derive the irreversibilities and entropy fluxes of the quantum and classical processes that intrinsically limit the performance of thermionic and tunneling chillers. The fundamental tradeoff between cooling flux and efficiency can then be evaluated, including the ramifications for feasible cooling regimes. Quantitative illustrations are provided for real solid-state devices. We cast these results as trajectories in the temperature-entropy plane and unify the thermodynamic perspective of these quantum chillers with that of conventional cooling cycles.