Functional extension and upgrade of a reactive ion etching tool

• Subject Area: Condensed Matter Physics
• Term: Funded in 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 495043546

With the requested funding, the Reactive Ion Etching System in the cleanroom of the Faculty of Physics will be upgraded with the option of inductively coupled plasma excitation. The inductively coupled plasma technology allows an independent adjustment of the ion and the plasma density. In this way, the etching process can be controlled very precisely, which is indispensable for many current research projects. One of the projects that the upgrade is critical for is the investigation of van-der-Waals heterostructures. For example, it will allow to fabricate samples that allow to investigate the fragile fractional quantum Hall effect in bilayer graphene. Additionally, experiments are planned to investigate the electronic structure of 2D materials with twisted layers. One goal is to gain a better understanding of the superconducting state which has been observed in twisted graphene double layers. In order to reveal the intrinsic properties of such van der-Waals heterostructures, any interaction with the substrate must be prevented. This can be achieved by encapsulating the functional layers in insulating boron nitride. For this process, the inductively coupled plasma mode with a precise control of the etching rate is absolutely essential. Moreover, the inductively coupled plasma mode also allows nanostructure etching with high aspect ratio, high shape fidelity and low edge roughness which is critical for the field of X-ray optics for coherent X-ray imaging in order to investigate the structure of biological systems on multiple scales. At this point, the applied for plasma technology is crucial for the further development of diffractive optics and for the realization of nanostructured X-ray anodes, which can generate a nano-focus at low power. Ultimately, the group plans to demonstrate the new concept "X-ray Optics on a Chip", which is intended to realize novel pump-probe, interferometric, tomographic and X-ray quantum optical experiments. A further use case for the upgraded plasma tool is the investigation ultrafast phenomena in solids and nanostructures where it will be allow the development and application of suitable spectroscopy, microscopy and diffraction techniques. For this purpose, extremely compact electron optics are required. It is planned to fabricate next-generation electron optics using lithographic processes in combination with deep reactive ion etching in the applied for etching mode.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Funktionserweiterung und Upgrade einer Anlage für reaktives Ionenätzen
• Instrumentation Group: 0920 Atom- und Molekularstrahl-Apparaturen
• Applicant Institution: Georg-August-Universität Göttingen
• Leader: Professor Dr. R. Thomas Weitz