Jpn. J. Appl. Phys. 46 (2007) pp. 5719-5723  |Previous Article| |Next Article|  |Table of Contents|
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High Speed Phase Change Random Access Memory with (Ge₁Sb₂Te₄)_0.9(Sn₁Bi₂Te₄)_0.1 Complete Solid Solution

Dong-Ho Ahn, Tae-Yon Lee¹, Dong-Bok Lee, Sung-Soo Yim, Jung-Sub Wi, Kyung-Bae Jin, Min-Hyun Lee, Ki-Bum Kim, Dae-Hwan Kang², Han-ju Jeong², and Byung-ki Cheong²

(Received December 11, 2006; revised June 25, 2007; accepted June 27, 2007; published online September 7, 2007)

We investigated structures and phase transformation kinetics of (Ge₁Sb₂Te₄)_0.9(Sn₁Bi₂Te₄)_0.1 alloy mixture and its application for the phase change random access memory device. As-sputtered (Ge₁Sb₂Te₄)_0.9(Sn₁Bi₂Te₄)_0.1 thin film forms crystalline fcc phase. Meanwhile, we could obtain amorphous RESET state and crystalline SET state reproducibly by using appropriate voltage pulse conditions in device structure. We demonstrate that the minimum time for SET operation of phase change random access memory device with (Ge₁Sb₂Te₄)_0.9(Sn₁Bi₂Te₄)_0.1 goes down to 20 ns, which is much smaller than 100 ns for device with Ge₁Sb₂Te₄. The accelerated SET operation of the device with (Ge₁Sb₂Te₄)_0.9(Sn₁Bi₂Te₄)_0.1 is interpreted to originate from reduced bond strength in comparison to pure Ge₁Sb₂Te₄.

KEYWORDS: Ge₁Sb₂Te₄, PRAM, Sn₁Bi₂Te₄, complete solid solution, amorphous, fcc, hcp, crystallization, activation energy
URL: http://jjap.ipap.jp/link?JJAP/46/5719/
DOI: 10.1143/JJAP.46.5719

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17. In our device structure, I_SET is relatively high because of large heat dissipation through the large top electrode.
18. From Fig. 6, we can determine the minimum pulse width for the crystallization or SET operation, which does not mean that total energy for the SET operation is constant. In other words, 2.0 V×5 mA×20 ns corresponds to the minimum energy required for the crystallization.