Local characterization and transformation of phase-change media by scanning thermal probes

Scanning thermal microscopy is applied to investigate the local thermal properties of thin phase-change (Ge2Sb2Te5) layers. The thermal contrast allows crystalline and amorphous areas to be detected unambiguously, and can be quantitatively linked to the crystalline ratio of the phase change layer. It is demonstrated that the heated tip can be used to locally crystallize parts of an amorphous Ge2Sb2Te5 layer, thereby suggesting thermal probes may be used for data storage applications on phase-change media (write once).