Chemistry and Materials Design, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zürich, 8092 Zürich, Switzerland.
Integrated Systems Laboratory, Department of Information Technology and Electrical Engineering, ETH Zürich, 8092 Zürich, Switzerland.
ACS Nano. 2023 Apr 11;17(7):6985-6997. doi: 10.1021/acsnano.3c01187. Epub 2023 Mar 27.
A structural change between amorphous and crystalline phase provides a basis for reliable and modular photonic and electronic devices, such as nonvolatile memory, beam steerers, solid-state reflective displays, or mid-IR antennas. In this paper, we leverage the benefits of liquid-based synthesis to access phase-change memory tellurides in the form of colloidally stable quantum dots. We report a library of ternary MGeTe colloids (where M is Sn, Bi, Pb, In, Co, Ag) and then showcase the phase, composition, and size tunability for Sn-Ge-Te quantum dots. Full chemical control of Sn-Ge-Te quantum dots permits a systematic study of structural and optical properties of this phase-change nanomaterial. Specifically, we report composition-dependent crystallization temperature for Sn-Ge-Te quantum dots, which is notably higher compared to bulk thin films. This gives the synergistic benefit of tailoring dopant and material dimension to combine the superior aging properties and ultrafast crystallization kinetics of bulk Sn-Ge-Te, while improving memory data retention due to nanoscale size effects. Furthermore, we discover a large reflectivity contrast between amorphous and crystalline Sn-Ge-Te thin films, exceeding 0.7 in the near-IR spectrum region. We utilize these excellent phase-change optical properties of Sn-Ge-Te quantum dots along with liquid-based processability for nonvolatile multicolor images and electro-optical phase-change devices. Our colloidal approach for phase-change applications offers higher customizability of materials, simpler fabrication, and further miniaturization to the sub-10 nm phase-change devices.
非晶态和晶态之间的结构变化为可靠和模块化的光子和电子设备提供了基础，例如非易失性存储器、光束转向器、固态反射显示器或中红外天线。在本文中，我们利用基于液体的合成的优势，以胶体稳定量子点的形式获得相变存储碲化物。我们报告了一系列三元 MGeTe 胶体（其中 M 是 Sn、Bi、Pb、In、Co、Ag），然后展示了 Sn-Ge-Te 量子点的相、组成和尺寸可调性。Sn-Ge-Te 量子点的完全化学控制允许对这种相变纳米材料的结构和光学性质进行系统研究。具体来说，我们报告了 Sn-Ge-Te 量子点的结晶温度随组成的依赖性，与体薄膜相比，其结晶温度显著更高。这带来了协同的好处，即可以调整掺杂剂和材料尺寸，将体 Sn-Ge-Te 的优异老化性能和超快结晶动力学结合起来，同时由于纳米尺寸效应而提高存储数据保持率。此外，我们发现非晶态和晶态 Sn-Ge-Te 薄膜之间存在很大的反射率对比度，在近红外光谱区域超过 0.7。我们利用 Sn-Ge-Te 量子点的这些出色的相变光学性质以及基于液体的可加工性，实现了非易失性多色图像和电光相变器件。我们用于相变应用的胶体方法提供了更高的材料可定制性、更简单的制造以及向亚 10nm 相变器件的进一步小型化。
