Evolution of Physical Models for ZnO-Varistors

On the origin of the electrical activity in silicon grain boundaries

“…In the first category, one may find baryum titanate capacitors, zinc oxyde varistors and polycrystalline silicon interconnections ; in the second are situated bulk poly-Si solar cells and thin-film poly-Si field effect transistors. The films are particularly interesting to develop 3-D integrated circuits [9][10][11][12][13][14][15].…”

“…The states trap the majority carriers on the one hand (electrons in a n-type semiconductor), thus creating a potential barrier at GB and a depleted zone in the neighbouring grains (see Fig. 1), which are respectively the origin of resistance and capacitance effects very usefull for instance in semiconducting ceramics [9][10][11]. On the other hand, these states are attractive and recombination centres for the minority carriers (holes in the same material), lowering the efficiency of poly-Si solar cells [12].…”