Study of interfaces between phase-change material Ge 2Sb 2Te 5 and prevalent complementary metal-oxide semiconductor materials by XPS

Abstract

The energy band alignment between Ge 2Sb 2Te 5 (GST) and common microelectronic materials such as dielectrics and metals was investigated using XPS. Energy band lineups of GST with various complementary metal-oxide semiconductor dielectrics, that is, SiO 2, HfO 2, Ta 2O 5 and Si 3N 4, were thus determined, which can be used as for phase change memory device engineering and integration with complementary metal-oxide semiconductor technology. Hole barrier height at metal/GST interface is reduced slightly by increasing the work function of the metal. Doping GST with nitrogen leads to an increase in hole barrier height at the interface between metals and nitrogen-doped GST. Significant pinning of metal Fermi level towards the valence band energy of undoped and nitrogen-doped GST was discovered. This leads to low hole barrier height and good ohmic contact formed between metals and GST. The hole barrier height between crystalline GST and various metals appears to increase as compared with the amorphous state. Copyright © 2012 John Wiley & Sons, Ltd. Copyright © 2012 John Wiley & Sons, Ltd.