Direct hexagonal transition of amorphous (Ge<inf>2</inf>Sb<inf>2</inf>Te<inf>5</inf>)<inf>0.9</inf>Se<inf>0.1</inf> thin films

Vinod Madhavan, K. Ramesh, R. Ganesan, K. S. Sangunni

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Ge<inf>2</inf>Sb<inf>2</inf>Te<inf>5</inf> (GST) is well known for its phase change properties and applications in memory and data storage. Efforts are being made to improve its thermal stability and transition between amorphous and crystalline phases. Various elements are doped to GST to improve these properties. In this work, Se has been doped to GST to study its effect on phase change properties. Amorphous GST film crystallized in to rock salt (NaCl) type structure at 150°C and then transformed to hexagonal structure at 250°C. Interestingly, Se doped GST ((GST)<inf>0.9</inf>Se<inf>0.1</inf>) film crystallized directly into hexagonal phase and the intermediate phase of NaCl is not observed. The crystallization temperature (T<inf>c</inf>) of (GST)<inf>0.9</inf>Se<inf>0.1</inf> is around 200°C, which is 50°C higher than the T<inf>c</inf> of GST. For (GST)<inf>0.9</inf>Se<inf>0.1</inf>, the threshold switching occurs at about 4.5V which is higher than GST (3V). Band gap (E<inf>opt</inf>) values of as deposited films are calculated from Tauc plot which are 0.63eV for GST and 0.66eV for (GST)<inf>0.9</inf>Se<inf>0.1</inf>. The E<inf>opt</inf> decreases for the films annealed at higher temperatures. The increased T<inf>c</inf>, E<inf>opt</inf>, the contrast in resistance and the direct transition to hexagonal phase may improve the data readability and thermal stability in the Se doped GST film.

Original languageEnglish
Article number063505
JournalApplied Physics Letters
Volume104
Issue number6
DOIs
Publication statusPublished - 2 Oct 2014
Externally publishedYes

Fingerprint

thin films
thermal stability
halites
data storage
plots
crystallization
thresholds
temperature

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

Cite this

Direct hexagonal transition of amorphous (Ge<inf>2</inf>Sb<inf>2</inf>Te<inf>5</inf>)<inf>0.9</inf>Se<inf>0.1</inf> thin films. / Madhavan, Vinod; Ramesh, K.; Ganesan, R.; Sangunni, K. S.

In: Applied Physics Letters, Vol. 104, No. 6, 063505, 02.10.2014.

Research output: Contribution to journalArticle

@article{aadc0ce1da9d42cda6f3397dca924683,
title = "Direct hexagonal transition of amorphous (Ge2Sb2Te5)0.9Se0.1 thin films",
abstract = "Ge2Sb2Te5 (GST) is well known for its phase change properties and applications in memory and data storage. Efforts are being made to improve its thermal stability and transition between amorphous and crystalline phases. Various elements are doped to GST to improve these properties. In this work, Se has been doped to GST to study its effect on phase change properties. Amorphous GST film crystallized in to rock salt (NaCl) type structure at 150°C and then transformed to hexagonal structure at 250°C. Interestingly, Se doped GST ((GST)0.9Se0.1) film crystallized directly into hexagonal phase and the intermediate phase of NaCl is not observed. The crystallization temperature (Tc) of (GST)0.9Se0.1 is around 200°C, which is 50°C higher than the Tc of GST. For (GST)0.9Se0.1, the threshold switching occurs at about 4.5V which is higher than GST (3V). Band gap (Eopt) values of as deposited films are calculated from Tauc plot which are 0.63eV for GST and 0.66eV for (GST)0.9Se0.1. The Eopt decreases for the films annealed at higher temperatures. The increased Tc, Eopt, the contrast in resistance and the direct transition to hexagonal phase may improve the data readability and thermal stability in the Se doped GST film.",
author = "Vinod Madhavan and K. Ramesh and R. Ganesan and Sangunni, {K. S.}",
year = "2014",
month = "10",
day = "2",
doi = "10.1063/1.4865198",
language = "English",
volume = "104",
journal = "Applied Physics Letters",
issn = "0003-6951",
publisher = "American Institute of Physics Publising LLC",
number = "6",

}

TY - JOUR

T1 - Direct hexagonal transition of amorphous (Ge2Sb2Te5)0.9Se0.1 thin films

AU - Madhavan, Vinod

AU - Ramesh, K.

AU - Ganesan, R.

AU - Sangunni, K. S.

PY - 2014/10/2

Y1 - 2014/10/2

N2 - Ge2Sb2Te5 (GST) is well known for its phase change properties and applications in memory and data storage. Efforts are being made to improve its thermal stability and transition between amorphous and crystalline phases. Various elements are doped to GST to improve these properties. In this work, Se has been doped to GST to study its effect on phase change properties. Amorphous GST film crystallized in to rock salt (NaCl) type structure at 150°C and then transformed to hexagonal structure at 250°C. Interestingly, Se doped GST ((GST)0.9Se0.1) film crystallized directly into hexagonal phase and the intermediate phase of NaCl is not observed. The crystallization temperature (Tc) of (GST)0.9Se0.1 is around 200°C, which is 50°C higher than the Tc of GST. For (GST)0.9Se0.1, the threshold switching occurs at about 4.5V which is higher than GST (3V). Band gap (Eopt) values of as deposited films are calculated from Tauc plot which are 0.63eV for GST and 0.66eV for (GST)0.9Se0.1. The Eopt decreases for the films annealed at higher temperatures. The increased Tc, Eopt, the contrast in resistance and the direct transition to hexagonal phase may improve the data readability and thermal stability in the Se doped GST film.

AB - Ge2Sb2Te5 (GST) is well known for its phase change properties and applications in memory and data storage. Efforts are being made to improve its thermal stability and transition between amorphous and crystalline phases. Various elements are doped to GST to improve these properties. In this work, Se has been doped to GST to study its effect on phase change properties. Amorphous GST film crystallized in to rock salt (NaCl) type structure at 150°C and then transformed to hexagonal structure at 250°C. Interestingly, Se doped GST ((GST)0.9Se0.1) film crystallized directly into hexagonal phase and the intermediate phase of NaCl is not observed. The crystallization temperature (Tc) of (GST)0.9Se0.1 is around 200°C, which is 50°C higher than the Tc of GST. For (GST)0.9Se0.1, the threshold switching occurs at about 4.5V which is higher than GST (3V). Band gap (Eopt) values of as deposited films are calculated from Tauc plot which are 0.63eV for GST and 0.66eV for (GST)0.9Se0.1. The Eopt decreases for the films annealed at higher temperatures. The increased Tc, Eopt, the contrast in resistance and the direct transition to hexagonal phase may improve the data readability and thermal stability in the Se doped GST film.

UR - http://www.scopus.com/inward/record.url?scp=84904992661&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84904992661&partnerID=8YFLogxK

U2 - 10.1063/1.4865198

DO - 10.1063/1.4865198

M3 - Article

AN - SCOPUS:84904992661

VL - 104

JO - Applied Physics Letters

JF - Applied Physics Letters

SN - 0003-6951

IS - 6

M1 - 063505

ER -