Specific Negative Resistance in Solids

The inherent instability associated with a specific differential negative resistance in a solid is discussed for the two cases voltage-controlled and current-controlled differential negative resistance. In the case of voltage-controlled differential negative resistance, it is shown that domains of high electric field occur. These domains are generally mobile and their movement is discussed. In the case, of current-controlled differential negative resistance, high current filaments form. The sizes of the domains and filaments are governed by the size of the specimen and by the principle of least entropy production. The effect of an external circuit is to inhibit stable filament formation in the case of current-controlled differential negative resistance and impose conditions under which stable domain formation can be observed in the case of voltage-controlled differential negative resistance.