Electrical Resistivity of Liquid Ge2Sb2Te5 Based on Thin-Film and Nanoscale Device Measurements

Abstract

The electrical resistivity of liquid Ge2Sb2Te5 (GST) is obtained from dc-voltage measurements performed on thin GST films as well as from device-level microsecond-pulse voltage and current measurements performed on two arrays (thicknesses: 20 +/- 2 nm and 50 +/- 5 nm) of lithographically defined encapsulated GST nano-/microwires (length: 315 to 675 nm; width: 60 to 420 nm) with metal contacts. The thin-film measurements yield 1.26 +/- 0.15 m Omega.cm (thicknesses: 50, 100, and 200 nm); however, there is significant uncertainty regarding the integrity of the film in liquid state. The device-level measurements utilize the melting of the encapsulated structures by a single voltage pulse while monitoring the current through the wire. The melting is verified by the stabilization of the current during the pulse. The resistivity of liquid GST is extracted as 0.31 +/- 0.04 and 0.21 +/- 0.03 m Omega.cm from 20- and 50-nm-thick wire arrays.