On the nature of chemical bonding in phase change materials on the base of (GeTe)m-(Sb2Te3)n alloys

Despite widespread use of pseudobinary alloys (GeTe)m-(Sb2Te3)n for manufacture of optical data storage memory interpretation of very fast crystallization and amorphization processes in these phase change materials (PCM) is still under discussion. To clarify the role of electron subsystem in unusual properties of PCM and to reveal the nature of their chemical bonding electron band structure calculations using WIEN2k program code were performed for compounds GeTe, Sb2Te3, GeSb2Te4 and Ge2Sb2Te5. Parameters of bond critic points in the electron density distribution for studied compounds and some related substances were obtained and analyzed. Characteristics of bond critic points inherent to basic PCM are established. They can be used as guide parameters for searching new perspective materials.