Phase separation behavior of Ge2Sb2Te5 line structure during electrical stress biasing

We report the breakdown behavior of a patterned Ge(2)Sb(2)Te(5) multiline structure during the voltage-driven electric stress biasing. Scanning Auger microscope analysis shows that the breakdown process accompanies with a phase separation of Ge(2)Sb(2)Te(5) into an Sb, Te-rich phase and a Ge-rich phase. The phase separation is explained by the incongruent melting of Ge(2)Sb(2)Te(5) based on the pseudobinary phase diagram between Sb(2)Te(3) and GeTe. It is claimed that this phase separation behavior by incongruent melting provides one of the plausible mechanisms of the device failure in a phase change memory. (c) 2008 American Institute of Physics.