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PcRAM
The technological challenges of scaling the current floating gate non-volatile memory technology to beyond the 32 nm technology node is tremendous, prompting the research for alternative technologies with PcRAM (phase-change random access memory) being one of the top contenders. By far the most widely used phase-change materials belong to the chalcogenide materials family including mainly the compounds of S, Se, and Te. The application that is closely related to our daily lives is rightfully the recording media of CDs and DVDs, for which lasers are used to induce the desired phase change. PcRAM application requires the corresponding phase change process be induced by electrical current and more importantly, significantly higher packing density of the information also known as “bits”. While the surface area occupied by one bit of information in CDs and DVDs is comparable to the wavelength of the laser (~0.5 m x 0.5 m), viable PcRAM application calls for the area for one bit to be ~100x smaller (~ 60 nm x 60 nm by year 2030). The much reduced volume in which one bit of information may be stored is associated with scientific and technological challenges that our research strives to address.
Our research aims at gaining fundamental understanding of the dynamics of the melting and crystallization processes in chalcogenide materials (specifically GeSb and Ge 0.2Sb 0.2Te 0.5) of nanometer volume. Our research focuses on three fundamental issues pertinent to the dynamics of phase change processes: the crystallization process, the melting process, and the thermal proximity effect. Our research aims at advancing the understanding of factors of fundamental physics nature that potentially limit the scaling of PcRAM technology. In situ transmission electron microscopy is the main experimental tool for our research.
Figure 1. The periodic table of elements.
Figure 2. Bright field images and the corresponding diffraction patterns of GST225
during a temperature cycle.
Figure 3. SEM image of patterned substrate for in situ TEM analysis.
Figure 4. Simulation of the temperature distribution and thermal proximity effect of PcRAM.
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Semiconductor Materials Research Laboratory, Department of Materials Science and Engineering, University of California at Los Angeles
Box 951595, Los Angeles, CA 90095-1595 (Tel) +1 310 825 2971 UCLA SMRL © 2006 | All Rights Reserved
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