We study the thermopower of a quantum dot weakly coupled to two reservoirs by tunnel junctions. At low temperatures the transport through the dot is suppressed by charging effects (Coulomb blockade). As a result the thermopower shows an oscillatory dependence on the gate voltage. We study this dependence in the limit of low temperatures where the transport through the dot is dominated by the processes of inelastic cotunneling. We also obtain a crossover formula for intermediate temperatures which connects our cotunneling results to the known sawtooth behavior in the sequential tunneling regime. As the temperature is lowered, the amplitude of thermopower oscillations increases, and their shape changes qualitatively.

We semiclassically derive the leading off-diagonal correction to the spectral form factor of quantum systems with a chaotic classical counterpart. To this end we present a phase space generalization of a recent approach for uniformly hyperbolic systems [1,2]. Our results coincide with corresponding random matrix predictions. Furthermore, we study the transition from the Gaussian orthogonal to the Gaussian unitary ensemble.

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Industrial bifacial PERC solar cells are exposed to a high‐voltage stress at the rear side. The tested cells show a potential‐induced degradation (PID) in Voc and Isc. From a front side current–voltage measurement, a power loss of about 12%rel is observed, however, without a significant change in the fill factor. The degradation is traced back to micron‐sized hole‐shaped damages of the rear surface, which correlate with localized regions of increased recombination. A focused ion beam (FIB) cross‐section through a hole‐shaped damage is performed for subsequent transmission electron microscopy (TEM) and energy‐dispersive X‐ray spectroscopy (EDXS). EDXS shows an accumulation of Na, K, and Ca impurities in the cavity. Thus, it is assumed that corrosion of the Si surface occurs beneath the AlOx/SiNy passivation layer stack and is accompanied by the formation of a SiO2 layer.

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