In the summer of 2009 at the Advanced Photon Source we studied the extended x-ray absorption spectra (or EXAFS) of samples of Germanium-Antimony-Tellurium (or GST) memory cells. Shown below is a sample a few microns across and a few tens of nanometers thick of GST. Between two crossed tungsten electrodes, the cell itself appears red. We are currently analyzing our spectra of samples such as these to study the atomic structure of the GST in different memory states. By studying the EXAFS at the germanium absorption edge, for example, we are able to determine the bonding environment of the germanium atoms.
