Percolation breakdown of amorphous semiconductors

A model for an initial stage of electrical breakdown of amorphous semiconductors is suggested. This model is based on the concept of the well-known processes of the field-assisted ionization of traps. A specific feature of the suggested model is a process of the interaction of isolated conductive clusters by means of redistribution of local electric fields and electron emission probabilities in non-conductive regions. The result of this process is the strengthening of fluctuations of local electric fields in regions with high density of conductive clusters and a weakening of local electric fields in regions with low density of conductive clusters. Finally, the conductive cluster that crosses electrodes arises and, as result, the breakthrough current appears. Dissipation of Joule heat stimulates the strengthening of the percolation path and the formation of a current filament, which connects the electrodes by the shortest path. Main dynamic parameters of the breakdown were calculated by computer simulation. The results of the simulation are supported by the data from physical experiments carried out on chalcogenide semiconductor glasses.