Next Generation Phase Change Memory Materials: Nanostructure, Electronic Properties and Thermal Transformations

下一代相变存储材料：纳米结构、电子特性和热转变

• 批准号: 0706267
• 负责人: Stephen Bishop
• 金额: $ 40.68万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0706267&HistoricalAwards=false
• 关键词: Next; Generation; Phase; Change; Memory

Technical: This project is to conduct fundamental study of phase change memory materials, including doped binary and exploratory ternary compositions of chalcogenide thin films. The objective is to achieve a detailed understanding of the phase-changing mechanism and the following properties of these materials: the nanoscale structure of the amorphous phase; thermal heat release during phase transitions; incorporation site, possible electrical activation, and structural effects of dopants; composition dependence of the valence band density of states; and the modifications resulting from alloy composition, conditions of synthesis including doping, and post-deposition thermal or optical processing. Scanning transmission electron microscopy, coupled with statistical data processing, will be used to characterize the effect of thermal history and composition on nanoscale structural order. Key objectives include determination of change induced by laser priming or melt-quenching and examination of structural changes associated with write/erase cycles. Nanocalorimetry will be used to study the heat capacity of each phase. Valence band density of states, including band tails and states in the gap, relationships to crystal structure, and switching mechanism, will be probed by measurements of the electrical conductivity and its temperature dependence; optical spectroscopy of the band gap absorption edge; and X-ray and UV photoemission. Pump-probe laser-induced phase transformations and in-situ measurements of the reflectivity will be carried out as a function of time. Phenomena to be studied during the transformations include atomic force microscopy of crystallites in a partially crystallized thin film sample and crystallinity and directionality of the crystallites using electron backscattered diffraction.Non-technical: Future development of chalcogenide materials for advanced data storage applications requires mastery of the relationship between composition, structure, thermal transformation, and electronic properties. This project, focusing on the fundamental materials research, will generate a deep scientific understanding of the nanoscale structure, thermal properties, electronic properties, and kinetics of the phase transformation of the phase change memory materials, enabling rapid development of optical memory and non-volatile memory based on phase change materials. The project will support two graduate students. One or two undergraduates will carry out portions of this project as their senior theses. To broaden the participation of underrepresented groups, qualified students will be identified through the SURGE (Support of Under-represented Groups in Engineering) and WISE (Women in Science and Engineering) programs at the University of Illinois - Urbana Champaign.

技术支持：本计画系进行相变化记忆体材料之基础研究，包括硫系化合物薄膜之二元掺杂及三元探索性组成。其目的是实现相变机制和这些材料的以下性质的详细理解：非晶相的纳米级结构;相变过程中的热释放;掺入位点，可能的电激活，和掺杂剂的结构效应;价带态密度的组成依赖性;以及由合金组成、合成条件（包括掺杂）和沉积后热或光学处理产生的改性。扫描透射电子显微镜，再加上统计数据处理，将被用来表征热历史和组成对纳米级结构顺序的影响。主要目标包括确定激光引发或熔化淬火引起的变化，以及检查与写入/擦除周期相关的结构变化。纳米量热法将用于研究每个相的热容。价带态密度，包括带尾和状态的差距，晶体结构的关系，和开关机制，将探讨通过测量的电导率和温度依赖性;光谱的带隙吸收边;和X射线和紫外光电子能谱。泵浦-探测激光诱导相变和反射率的原位测量将作为时间的函数进行。现象的研究过程中的转变，包括原子力显微镜的微晶在部分结晶的薄膜样品和结晶度和方向性的微晶使用电子背散射diffraction.Non-technical：未来发展的硫属化物材料的先进数据存储应用需要掌握的组成，结构，热转换和电子性能之间的关系。该项目以基础材料研究为重点，将对相变存储材料的纳米级结构、热性能、电子性能和相变动力学产生深刻的科学认识，使基于相变材料的光存储器和非易失性存储器得以快速发展。该项目将资助两名研究生。一个或两个本科生将执行这个项目的一部分，作为他们的毕业论文。为了扩大代表性不足的群体的参与，将通过伊利诺伊大学厄巴纳尚潘分校的SURGE（支持工程领域代表性不足的群体）和WISE（科学和工程领域的妇女）方案来确定合格的学生。