Role of inelastic electron–phonon scattering in electron transport through ultra-scaled amorphous phase change material nanostructures
- 312 Downloads
The electron transport through ultra-scaled amorphous phase change material (PCM) GeTe is investigated by using ab initio molecular dynamics, density functional theory, and non-equilibrium Green’s function, and the inelastic electron–phonon scattering is accounted for by using the Born approximation. It is shown that, in ultra-scaled PCM device with 6 nm channel length, \(<\)4 % of the energy carried by the incident electrons from the source is transferred to the atomic lattice before reaching the drain, indicating that the electron transport is largely elastic. Our simulation results show that the inelastic electron–phonon scattering, which plays an important role to excite trapped electrons in bulk PCM devices, exerts very limited influence on the current density value and the shape of current–voltage curve of ultra-scaled PCM devices. The analysis reveals that the Poole–Frenkel law and the Ohm’s law, which are the governing physical mechanisms of the bulk PCM devices, cease to be valid in the ultra-scaled PCM devices.
KeywordsPhase change material Non-equilibrium Green’s function (NEGF) Electron phonon scattering Mean free path (MFP) Ultra-scaled nanostructure
This work was supported by U.S. National Science Foundation (NSF) under Grant Award 1006182. We acknowledge the Pacific Northwest National Laboratory (PNNL) for providing computational resources on the PNNL Chinook supercomputers. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant number OCI-1053575. This work was facilitated through the use of advanced computational, storage, and networking infrastructure provided by the Hyak supercomputer system, supported in part by the University of Washington’s eScience Institute. We acknowledge J. Akola and R.O. Jones (for discussion about AIMD simulations).
- 5.Liu, J., Yu, B., Anantram, M.P.: Isotropic and anisotropic scaling analysis of nanowire phase change memory. 11th IEEE Conference on Nanotechnology, pp. 1343–1347 (2011)Google Scholar
- 6.Raoux, S., Wuttig, M. (eds.): Phase Change Materials Science and Applications. Springer, New York (2009)Google Scholar
- 14.Raoux, S., Rettner, C.T., Jordan-Sweet, J.L., Deline, V.R., Philipp, J.B., Lung, H.L.: Scaling properties of phase change nanostructures and thin films. Proc. Euro. Symp. on Phase Change and Ovonic Science, pp. 127–134 (2006)Google Scholar
- 15.Wong, H.-S.P., Kim, S., Lee, B., Caldwell, M.A., Liang, J.L., Wu, Y., Jeyasingh, R.G.D., Yu, S.M.: Recent progress of phase change memory (PCM) and resistive switching random access memory (RRAM). 10th IEEE International Conference on Solid-State and Integrated Circuit Technology, pp. 1055–1060 (2010)Google Scholar
- 21.Hegedus, J., Elliott, S.R.: Microscopic origin of the fast crystallization ability of Ge–Sb–Te phase-change memory materials. Nat. Mater. 7, 399–405 (2008)Google Scholar
- 26.Akola, J., Jones, R.O., Kohara, S., Kimura, S., Kobayashi, K., Takata, M., Matsunaga, T., Kojima, R., Yamada, N.: Experimentally constrained density-functional calculations of the amorphous structure of the prototypical phase-change material Ge2 Sb2 Te5. Phys. Rev. B 80(1–4), 020201 (2009)CrossRefGoogle Scholar
- 30.Soler, J.M., Artacho, E., Gale, J.D., Garca, A., Junquera, J., Ordejon, P., Sanchez-Portal, D.: The SIESTA method for ab initio order-N materials simulation. J. Phys. Condens. Matter 14, 2745–2779 (2002) Google Scholar
- 37.Liu, J.: Multiscale simulation of phase change memory. PhD thesis, University of Washington, Seattle, WA, USAGoogle Scholar