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Title: Direct Observation of Amorphous to Crystalline Phase Transitions in Nano-Particle Arrays of Phase Change Materials

Abstract

We have used time-resolved x-ray diffraction to study the amorphous-crystalline phase transition in 20-80?nm particles of the phase change materials Ge2Sb2Te5, nitrogen-doped Ge2Sb2Te5, Ge15Sb85, Sb2Te, and Sb2Te doped with Ag and In. We find that all samples undergo the phase transition with crystallization temperatures close to those of similarly prepared blanket films of the same materials with the exception of Sb2Te that shows the transition at a temperature that is about 40? C higher than that of blanket films. Some of the nanoparticles show a difference in crystallographic texture compared to thick films. Large area arrays of these nanoparticles were fabricated using electron-beam lithography, keeping the sample temperatures well below the crystallization temperatures so as to produce particles that were entirely in the amorphous phase. The observation that particles with diameters as small as 20?nm can still undergo this phase transition indicates that phase change solid-state memory technology should scale to these dimensions.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
959692
Report Number(s):
BNL-82678-2009-JA
Journal ID: ISSN 0021-8979; JAPIAU; TRN: US201016%%836
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 102
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRYSTALLIZATION; DIMENSIONS; PHASE CHANGE MATERIALS; TEXTURE; X-RAY DIFFRACTION; PHASE TRANSFORMATIONS; national synchrotron light source

Citation Formats

Raoux,S., Rettner, C., Jordan-Sweet, J., Kellock, A., Topuria, T., Rice, P., and Miller, D.. Direct Observation of Amorphous to Crystalline Phase Transitions in Nano-Particle Arrays of Phase Change Materials. United States: N. p., 2007. Web. doi:10.1063/1.2801000.
Raoux,S., Rettner, C., Jordan-Sweet, J., Kellock, A., Topuria, T., Rice, P., & Miller, D.. Direct Observation of Amorphous to Crystalline Phase Transitions in Nano-Particle Arrays of Phase Change Materials. United States. doi:10.1063/1.2801000.
Raoux,S., Rettner, C., Jordan-Sweet, J., Kellock, A., Topuria, T., Rice, P., and Miller, D.. Mon . "Direct Observation of Amorphous to Crystalline Phase Transitions in Nano-Particle Arrays of Phase Change Materials". United States. doi:10.1063/1.2801000.
@article{osti_959692,
title = {Direct Observation of Amorphous to Crystalline Phase Transitions in Nano-Particle Arrays of Phase Change Materials},
author = {Raoux,S. and Rettner, C. and Jordan-Sweet, J. and Kellock, A. and Topuria, T. and Rice, P. and Miller, D.},
abstractNote = {We have used time-resolved x-ray diffraction to study the amorphous-crystalline phase transition in 20-80?nm particles of the phase change materials Ge2Sb2Te5, nitrogen-doped Ge2Sb2Te5, Ge15Sb85, Sb2Te, and Sb2Te doped with Ag and In. We find that all samples undergo the phase transition with crystallization temperatures close to those of similarly prepared blanket films of the same materials with the exception of Sb2Te that shows the transition at a temperature that is about 40? C higher than that of blanket films. Some of the nanoparticles show a difference in crystallographic texture compared to thick films. Large area arrays of these nanoparticles were fabricated using electron-beam lithography, keeping the sample temperatures well below the crystallization temperatures so as to produce particles that were entirely in the amorphous phase. The observation that particles with diameters as small as 20?nm can still undergo this phase transition indicates that phase change solid-state memory technology should scale to these dimensions.},
doi = {10.1063/1.2801000},
journal = {Journal of Applied Physics},
number = ,
volume = 102,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}