Transmission electron microscopy of stressed GeSex-based threshold switching devices

Abstract

Two types of nanoscale structures with amorphous GeSex functional layers were fabricated to assess the elemental segregation in devices stressed by the application of an electric field and/or a temperature gradient. An electric field of 1.3 × 108 V m−1 and a current density of 1.5 × 106 A cm−2 resulted in the pronounced segregation of Ge toward the cathode with lesser segregation of Se in the same direction. The segregation direction reversed upon reversal of the field consistent with the electromigration mechanism. The electric field/current stress also produced voids forming in the proximity of the anode and noticeable concentration of W in the chalcogenide layer. Stressing the structures in a temperature gradient of 3 × 109 K m−1 at 630 K average temperature did not affect the elemental distributions.