Indexed by: Journal paper

First Author: 马平

Correspondence Author: 缪向水

Co-author: 孙成军,程晓敏,余念念,徐明,黄婷,TONG HAO

Journal: JOURNAL OF PHYSICAL CHEMISTRY C

Affiliation of Author(s): 华中科技大学

Discipline: Engineering

First-Level Discipline: Electronic Science And Technology

Document Type: J

Volume: 121

Issue: 7

Page Number: 1122-1128

Key Words: Binding-energy Shifts;Phase-change;Carbon Nanotube;Crystallization;Ge2Sb2Te5;States;Edge;Coordination;Media;Gap

DOI number: 10.1021/acs.jpcc.6b09841

Date of Publication: 4275-04-01

Abstract: Phase-change materials, the highly promising candidate for nonvolatile data recording, present a different phase-change property when film thickness shrinks to very deep submicron scale. The local structure of amorphous GeTe ultrathin films, which contributes to the characteristics of phase change, is examined using X-ray absorption measurements. Ge atoms are found to be low-coordinated when the film thickness decreases. Ge atoms are linked to neighbor atoms by covalent bond, and the weaker Ge-Te bonds are more easily broken, which suggests that Ge atoms are located in the defective Ge2Te3 local arrangement. The mixture of se(3)/sp(2) hybridization and 3-coordinated Ge found in ab initio molecular dynamics simulations also supports this local motif. The exponential rise of crystallization temperatures of ultrathin films with decreasing film thickness, which is a vital parameter for phase change process, can be well explained by the proposed defective GeTe local arrangement.

Links to published journals: https://pubs.acs.org/doi/full/10.1021/acs.jpcc.6b09841