Atomic Layer Etching for 2DM studies

Background information on Project This tender is being run on behalf of Prof. Roman Gorbachev for the School of Physics and Astronomy/National Graphene Institute.

Project Overview The National Graphene Institute (NGI) has a large cleanroom facility housing a range of state-of-the-art instruments dedicated to the fabrication and characterization of 2D related metamaterials and devices for a broad range of applications, from advanced optoelectronics to nanofluidics. An essential part of many fabrication processes is the capability to dry etch materials. A range of plasma-based dry etching techniques have been developed for 2D materials (2DM), primarily to completely remove specific regions in order to create a pattern defined by a lithographic mask. "Thinning down" of atomically thin 2DM by etching so far remains problematic, as the surface amorphization leads to complete loss of their unique properties. Subsequently, "soft-plasma" etching techniques were developed to approach layer-by-layer etching of various 2DM. These methods provide great control of the thickness, but they are not self-limiting in nature due to associated physical etching processes and thus require careful optimization of many dry etching parameters. Even then, damage to the underlaying materials is frequent, limiting its use for nanotechnology applications that demand the highest crystal quality (quantum technologies, sensors, etc.). To overcome these limitations, this project aims to study the use of Atomic Layer Etching (ALE) of 2DM, using multi-step, self-limiting reactions to allow precise (layer-by-layer), highly selective and low damage etching. The proposed platform must include the capability to perform ALE in addition to the conventional inductively coupled plasma (ICP) and/or reactive ion etching (RIE) processes, with fast recipe control and fine tuning of low bias powers. Apart from "thinning down" of 2DM, more controllable and reliable ICP/RIE will also benefit a range of already existing processes in terms of reproducibility, uniformity and control, such as clean layer transfers for heterostructure fabrication and synthesis of high-quality ohmic contacts to 2DM.