| AVS 55th International Symposium & Exhibition | |
| Thin Film | Thursday Sessions |
| Session TF-ThP |
| Session: | Aspects of Thin Films |
| Presenter: | J.H. Lee, Seoul National University, South Korea |
| Authors: | J.H. Lee, Seoul National University, South Korea S.W. Ryu, Seoul National University, South Korea Y.B. Ahn, Seoul National University, South Korea C.S. Hwang, Seoul National University, South Korea H.J. Kim, Seoul National University, South Korea |
| Correspondent: | Click to Email |
Among the next-generation resistance based memories, PcRAM stores the digital data as different resistances of the phase change material between amorphous and crystalline phase. Although PcRAM has superior performances, there are still critical issues to be resolved i.e. reducing high amorphization current,1 enhancing slow crystallization speed. Ge2Sb2Te5 is the most well known phase change material for PRAM. Attempts has been made to improve the phase change properties of Ge2Sb2Te5 by doping various elements and compounds such as N,2 O3 and SiO2.4 In this report Ge2Sb2Te5 was manipulated by doping Bi. Incorporation of Bi into Ge2Sb2Te5 thin film was performed in two ways. First, by cosputtering Bi2Te3 and Ge2Sb2Te5. Second, by sputtering Ge2Bi2Te5 and Ge2Sb2Te5 simultaneously. By cosputtering Bi2Te3 and Ge2Sb2Te5, Bi was successfully incorporated into the lattice, which was confirmed by shifts in XRD peak positions compared to those of undoped Ge2Sb2Te5. Cosputtering Ge2Bi2Te5 and Ge2Sb2Te5 guaranteed fixed atomic percentage of Ge and Te in the film with varying Bi contents. When the amorphous Bi doped Ge2Sb2Te5 films crystallized by thermal annealing at about 150 °C, the resistivity of the film was reduced over 3 orders of magnitude, which was sufficient for device application. The Bi doped Ge2Sb2Te5 films showed lower amorphization voltage without having to increase the crystalline resistance and demonstrated faster crystallization speed than those of Ge2Sb2Te5.
1 K.N. Kim, J.H. Choi, J.D. Choi and H.S. Jeong, 2005 IEEE VLSI-TSA Int. Symp. on, pp 88-94.
2 Y.N. Hwang, S.H. Lee, S.J. Ahn, S.Y. Lee, K.C. Ryoo, H.S. Hong, H.C. Koo, F. Yeung, J.H. Oh, H.J. Kim, W.C. Jeong, J.H. Park, H. Horii, Y.H. Ha, J.H. Yi, G.H. Koh, G.T. Jeong, H.S. Jeong and K.N. Kim, IEDM '03 Technical Digest. IEEE International, 8-10, pp 37.1.1-37.1.4.
3 S. Privitera, E. Rimini and R. Zonca, Appl. Phys. Lett. 85, 3044 (2004).
4 S.W. Ryu, J. H. Oh, B. J. Choi, S.Y. Hwang, S. K. Hong, C. S. Hwang, and H. J. Kim, Electrochem. Solid-State Lett. , 9(8), G259-G261 (2006).