Wafer Scale Ultra-Clean Van der Waals Heterostructures

Introduction

Two dimensional materials (2DM) and their van der Waals (vdW) heterostructures have opened new opportunities to develop atomically thin electronic and optoelectronic devices with a wide range of functionalities. While thousands of research papers demonstrate proof-of-concept studies with improved and novel performance using small-scale exfoliated crystals, a number of challenges still remain when these are attempted to be scaled up on wafer-scale with CVD grown 2DM.

Challenges in Transfer Process

One of the key challenges is the transfer process of 2DM from their growth substrate to another 2DM or a target substrate for intended use. Currently, this process is performed using organic polymers to support 2DM, which introduces a considerable amount of contamination and mechanical damage to the transferred layers.

Proposed Solution

We propose to circumvent the existing issues of the transfer process by employing a new technique recently invented in NGI, which completely avoids the use of organic compounds. This approach enables the production of heterostructures with perfect interfaces free from interlayer contamination and correspondingly excellent (opto)electronic behaviour.

Advantages of the New Technique

In addition, eliminating polymeric supports allows new possibilities for vdW heterostructure fabrication:

1. Assembly at temperatures up to 600°C
2. Operation in different environments including ultra-high vacuum (UHV) and liquid submersion
3. Improved mechanical stability

Project Goals

This project will apply our novel approach for wafer-scale use, considering requirements of industrial companies, such as:

• The choice of 2DMs and wafers
• Quality standards
• Throughput
• Reliability

The improved inorganic transfer technology will then be licensed to a selected 2DM foundry.

Instrument Development

In addition, we will develop an instrument for wafer-scale 2DM transfer that employs our innovative approach, which will be made available via a spin-out company.

Conclusion

Successful completion of the project can bring life to a wide range of industrial exploitation of 2DM in industrial nanotechnology applications.