TY - JOUR
T1 - The importance of contacts in Cu2GeTe3phase change memory devices
AU - Shindo, Satoshi
AU - Shuang, Yi
AU - Hatayama, Shogo
AU - Saito, Yuta
AU - Fons, Paul
AU - Kolobov, Alexander V.
AU - Kobayashi, Keisuke
N1 - Funding Information:
This work was supported by the JSPS KAKENHI (Grant Nos. 15H04113, 17J03876, and 18H02053). A.V.K. acknowledges financial support from the Ministry of Education of the Russian Federation (project No. FSZN-2020-0026). The authors acknowledge Professor Junichi Koike for valuable discussions and comments. The synchrotron radiation experiments were performed at beamline BL47XU of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2015B1204).
Publisher Copyright:
© 2020 Author(s).
PY - 2020/10/28
Y1 - 2020/10/28
N2 - Cu2GeTe3 (CGT) is a promising phase change material for phase change random access memory (PCRAM) applications because of its high thermal stability in the amorphous phase and its capability to undergo rapid phase change. In this paper, the electrical conduction mechanism of a CGT memory device fabricated using W electrodes (W/CGT) was investigated using current-voltage (I-V) measurements and angle resolved hard x-ray photoelectron spectroscopy (AR-HAXPES). The I-V characteristics of the W/CGT memory device were found to display non-linear behavior in the RESET (amorphous) state, while linear behavior was observed in the SET (crystalline) state, indicating that the W/CGT memory device exhibited Schottky conduction in the RESET state, but Ohmic conduction in the SET state. The effective Schottky barrier height was found to increase linearly as the ideality factor decreased to unity with the ideal W/CGT Schottky barrier height in the RESET state estimated to be 0.33 eV, a value in good agreement with the directly measured Schottky barrier height of 0.35 eV between W and amorphous CGT by AR-HAXPES measurements. These results suggest that the interface between the metal electrode and the phase change material plays an important role in PCRAM devices, and its comprehensive understanding is necessary for future application development.
AB - Cu2GeTe3 (CGT) is a promising phase change material for phase change random access memory (PCRAM) applications because of its high thermal stability in the amorphous phase and its capability to undergo rapid phase change. In this paper, the electrical conduction mechanism of a CGT memory device fabricated using W electrodes (W/CGT) was investigated using current-voltage (I-V) measurements and angle resolved hard x-ray photoelectron spectroscopy (AR-HAXPES). The I-V characteristics of the W/CGT memory device were found to display non-linear behavior in the RESET (amorphous) state, while linear behavior was observed in the SET (crystalline) state, indicating that the W/CGT memory device exhibited Schottky conduction in the RESET state, but Ohmic conduction in the SET state. The effective Schottky barrier height was found to increase linearly as the ideality factor decreased to unity with the ideal W/CGT Schottky barrier height in the RESET state estimated to be 0.33 eV, a value in good agreement with the directly measured Schottky barrier height of 0.35 eV between W and amorphous CGT by AR-HAXPES measurements. These results suggest that the interface between the metal electrode and the phase change material plays an important role in PCRAM devices, and its comprehensive understanding is necessary for future application development.
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U2 - 10.1063/5.0019269
DO - 10.1063/5.0019269
M3 - Article
AN - SCOPUS:85094870981
SN - 0021-8979
VL - 128
JO - Journal of Applied Physics
JF - Journal of Applied Physics
IS - 16
M1 - 165105
ER -