Real-time imaging of light-induced transformations in phase-change materials

在这个数字时代，我们在日常生活的许多方面都依赖于计算机。他们的表现不仅影响我们的沟通和工作方式，也影响我们银行和医疗保健的效率。因此，投资于他们的发展以保持在该部门的战略优势符合加拿大的最佳利益。这项发现补助金（DG）通过研究相变材料的动力学来实现这一目标，这些材料对计算机存储设备非常重要，并有可能实现更高效的计算机架构。今天的计算机遵循冯·诺依曼架构，其中数据必须在物理上分离的处理和存储单元之间移动。由于处理器的速度已经超过了内存，现在的瓶颈是来回穿梭数据所需的时间。这可以通过在单个设备中执行两个操作来克服，称为内存计算。然而，这种器件的实际实现需要能够在状态之间快速且不可逆地切换的材料，以用于组合的快速处理和非易失性存储器功能。基于硫属化物合金的相变材料已经被大量研究用于此目的，并且已经用于计算机工业中的光学数据存储-组成Ge 2Sb 2 Te 5用于DVD，Ge 8 Sb 2 Te 11用于蓝光光盘。可以使用激光或电流将数据写入这些设备中，以局部加热一个小区域，并在绝缘非晶玻璃相和导电结晶相之间切换。所得到的相位由在由入射激光功率或电流控制的过程中吸收的热量确定。然而，最大数据写入速度目前受到非晶到结晶相变时间的限制。 然后，该DG的目标是探索提高这种转变速度的方法，并使用INRS的动态透射电子显微镜（DTEM）在真实的时间内跟踪相应的材料结构演变。这种独特的显微镜有能力捕捉一系列纳秒级图像的不可逆转变与近原子的分辨率。具体而言，该DG将通过探索以下研究方向来解决有关相变材料结晶的关键突出问题：（1）成像快速冷却的转变，（2）跟踪非晶相中的前体，以及（3）超局部纳米等离子体加热。这项研究有望加深对这一技术上重要的转变的理解，这可能会影响未来的计算机设计。此外，在该计划中培训的高素质人员所获得的专业知识可广泛转移到加拿大技术行业的其他部门。

In this digital age, we rely on computers in many aspects of our daily life. Their performance not only influences how we communicate and work, but also the efficacy of our banks and medical care. It is then in the best interest of Canada to invest in their development to maintain a strategic advantage in this sector. This Discovery Grant (DG) contributes to this goal by studying the dynamics of phase-change materials that are important for computer memory devices and have the potential to enable more efficient computer architectures. Today's computers follow a von Neumann architecture, where data must be moved between physically separate processing and memory units. As the speed of processors has outpaced that of memory, the bottle neck is now the time it takes to shuttle data back and forth. This can be overcome by performing both actions in a single device, referred to as in-memory computing. However, practical realization of such devices requires materials that can both rapidly and irreversibly switch between states for combined fast processing and non-volatile memory functionality. Phase-change materials based on chalcogenide alloys have been largely investigated for this purpose, and are already used in the computer industry for optical data storage - the composition Ge2Sb2Te5 is used in DVDs, and Ge8Sb2Te11 is used in Blue-ray disks. Data can be written in these devices using a laser or electric current to locally heat a small region, and switch it between an insulating amorphous glass phase and a conductive crystalline phase. The resultant phase is determined by the amount of heat absorbed in the process that is controlled by the incident laser power or electric current. However, the maximum data writing speed is currently limited by the amorphous to crystalline phase transformation time. It is then the goal of this DG to explore ways to increase this transformation speed and track the corresponding material structural evolution in real time using the dynamic transmission electron microscope (DTEM) at INRS. This unique microscope has the capability to capture a sequence of nanosecond images of irreversible transformations with near-atomic resolution. Specifically, this DG will address critical outstanding questions about the crystallization of phase-change materials by exploring the following research directives: (1) imaging rapidly cooled transformations, (2) tracking precursors in the amorphous phase, and (3) ultra-localized nano-plasmonic heating. This research is expected to lead to a deeper understanding of this technologically important transformation, which can impact the future design of computers. Furthermore, the expertise gained by highly qualified personnel trained in this program is widely transferable to other sectors of the Canadian technology industry.