Instabilities during highhyphen;field electrical conduction in solids

摘要

Measurements of the time and voltage dependence of dc and ac currents in insulators and semiconductors and the evaluation of results of other authors on corresponding measurements using metallic samples reveal that critical power densitiesNk1ap;10minus;8W/mm3andNk2ap;10minus;5W/mm3separate three different ranges of charge transport loading of solids in the frequency range 0les;fles;50 Hz. The loading state of a solid is described macroscopically by the average electric power density and microscopically by the local value of the power density jdrarr;sdot;Edrarr;. In semiconductors and insulators electrical breakdown or transition to a strongly localized and highly conducting state is unavoidable if an overcritical power densityNgsim;10minus;5W/mm3is supplied. This locally quite limited and highly conducting state exists in the prebreakdown range whereinNk2NNfusion. It is related to the Ovshinsky effect in amorphous semiconductors. Usually the current density, continuity, and Poisson equations are used to describe charge transport within a solid. In order to complete this description it is proposed that power densityN=jdrarr;sdot;Edrarr; must be considered.