Observation of chemical separation of In3Sb1Te2 thin film during phase transition

• Published in: Applied surface science Vol. 292; pp. 986 - 989
• Main Authors: Lee, Y.M., Baik, J., Shin, H.-J., Kim, Y.S., Yoon, S.G., Jung, M.-C., Qi, Y.B.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-02-2014; Elsevier
• Subjects: Annealing; Antimony; Chemical separation; Chemical state; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystal structure; Exact sciences and technology; In3Sb1Te2; Indium antimonides; Phase transformations; Phase-change random access memory; Physics; Stoichiometry; Synchrotron radiation; Thin films; X-ray photoelectron spectroscopy; Chemical state; In3Sb1Te2; X-ray photoelectron spectroscopy; Phase-change random access memory; Thin films; Te; Random-access storage; Phase transformations; In; X-ray photoelectron spectra; Sb
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2013.12.096

•The structural analysis of the In3Sb1Te2 thin film with increasing annealing temperature from 350 to 700°C using high-resolution X-ray photoelectron spectroscopy with synchrotron radiation was performed.•The original mechanism for the phase-change of In3Sb1Te2 is the chemical separation.•In the case of samples annealed above 450°C, the severe segregation and the depletion of the Sb atom were observed on the In3Sb1Te2 film surface.•A doping process using new elements in order to establish the stable state of the Sb atom during the phase transition was suggested.
We investigated the chemical states of In3Sb1Te2 (IST) thin film using high-resolution X-ray photoelectron spectroscopy (HRXPS) with the synchrotron radiation during in-situ annealing in ultra-high vacuum. To obtain the oxygen-free amorphous IST (a-IST), we performed the mild Ne+ ion sputtering. And also we confirmed the relative a-IST stoichiometry to be 54%:17%:29% based on HRXPS data. At the first and second phase transition temperatures of 350 and 400°C, we observed the dramatic changes of chemical states from a-IST to InSb and the mixture of crystalline-IST and InTe, respectively. There was a depletion of Sb atoms on the surface after annealing at 750°C. We assume that Sb atom is a key for the phase transition in IST. However, chemical state of the Sb in IST is unstable during the phase transition and it will be caused with the non-reversible process by this structural instability.