Electronic structure of (Ge2Sb2Te5)1−x(In3SbTe2)x investigated by x-ray photoelectron spectroscopy

Abstract

We have investigated the core levels and the valence band of (Ge2Sb2Te5)1−x(In3Sb1Te2)x quaternary phase system (IGST) by means of x-ray photoelectron spectroscopy. A systematic shift of Sb 3d and Ge 2p core-level peaks toward lower binding energies side was observed with increasing indium amount, whereas the In 3d and Te 3d core peaks showed less change. The Sb 3d and Ge 2p core-level shift is attributed to an increase in the electronic charge of p-electrons dependent of indium amount. The valence band spectra show a distinct change in the sp configuration with indium concentration change. The change in the local bonding as the indium amount increase has a profound impact on both local atomic arrangement and amorphous-to-crystalline transformation temperature. The difference in the photoemission spectra have been discussed according to a simple structural model suggesting that the Na site in IGST can be occupied by Te, Sb, In, and vacancy, whereas in GST it is occupied only by Te.

Phase-Change Characteristics and Crystal Structure in Multi Stacked GeTe/InTe Films

“…Recently, it has been reported that phase-change characteristics can be improved by adding bismuth, tin, or indium. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] Indium was considered an especially effective dopant for tailoring the properties of phase-change materials; it is expected to increase the crystallization temperature owing to the strong ionic bonds between indium and tellurium. However, the indium effect on the phase-change characteristics of GeTe-Sb 2 Te 3 systems has not been clarified because of phase segregation during sample preparation.…”