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Structural evolution of germanium-bismuth-telluride phase change materials for PRAM application with modulated RF-sputtering power on bismuth target

Chang Woo Sun 1Min Soo Youm 2Yong Tae Kim 2

1. Korea Advanced Institute of Science and Technology (KAIST), Yuseong, Daejeon 305-701, Korea, South
2. Korea Institute of Science and Technology, Semiconductor Materials and Devices Laboratory, Seoul 136-791, Korea, South

Abstract

RF-power modulated Ge-Bi-Te ternary chalcogenide thin film was deposited by co-sputtering Ge-Te and Bi target on SiO2/Si substrate in order to search the appropriate candidate for alternate phase change material. A differential scanning calorymetry (DSC) analysis, x-ray diffraction (XRD) analysis, auger electron spectroscopy (AES), and high resolution transmission electron microscopy (HR-TEM) studies are conducted in order to investigate the crystallization behavior of Ge-Bi-Te ternary alloy. The XRD results of each annealed samples showed that Ge-Bi-Te alloy crystallized into GeBi2Te4, Ge1Bi4Te7, Ge2Bi2Te5 phase around 300 °C according to Ge content and expelled Ge single phase appeared over 400 °C. Not only GeBi2Te4, Ge1Bi4Te7, Ge2Bi2Te5 phases but Ge phase was also confirmed with HR-TEM images and diffraction patterns of various zone axes. It is noted that some of Ge2Bi2Te5 grains show specific facetted planes like {0113}, {0112}, and {0001}. Through the successive analysis, we revealed the Ge-Bi-Te ternary alloy varies structure according to Ge contents and confirmed potential of Ge-Bi-Te alloy for the PRAM application.

 

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Related papers

Presentation: Poster at E-MRS Fall Meeting 2007, Symposium J, by Yong Tae Kim
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-14 11:03
Revised:   2009-06-07 00:44