Digital printing of 2D materials using laser light

Printed pixels made of single-layer graphene have been made by laser-induced forward transfer (LIFT). This novel digital printing technology offers interesting prospects for creating printed circuits from 2D materials. As a demonstration, researchers have made graphene field effect transistors (GFETs) with a high mobility, printed on a flexible substrate.

Image: Printing a pixel of 2D material with LIFT.

As part of a Horizon Europe project L2D2, researchers from the National Technical University (NTU) of Athens in Greece and Graphenea in Spain collaborated to make this technology work. The results were presented at the conference SPIE Photonics Europe 2024, and the presentation as well as the accompanying paper are openly available.

In the freely available recording of the presentation, researcher Filimon Zacharatos shows printing of 2D material pixels with lateral dimensions ranging from 40 to 200 micrometers. The work also shows the use of digital printing methods to produce metal contacts on flexible substrates, followed by LIFT deposition of graphene on top of the contacts. Such obtained graphene transistors have exceptionally high carrier mobilities, with the smallest devices exhibiting hole mobility of 1800 cm2/Vs. The researchers also demonstrate transfer of hexagonal boron nitride (hBN) and pre-produced hBN/graphene stacks, both very successfully.

The project, which kicked off in October 2022, has already produced significant results, including the demonstration of LIFT printing of various 2D materials, such as graphene, insulators, and semiconductors. The project was designed to upscale growth and transfer of graphene and other 2D materials in an eco-friendly green process, and it is already fulfilling some of the stated goals. Project L2D2 builds upon knowledge gained during project LEAF-2D, where laser is used to transfer 2D materials from one substrate to another. The laser transfer process allows chemical-free processing, as well as precise alignment of materials in heterostructures. In particular, L2D2 goes after two technological breakthroughs: upscaling graphene and other 2D materials to the 8-inch scale at industrial-grade quality, and wafer-scale integration of such materials with the aid of laser-assisted transfer.

The project plan includes protection of IP related to LIFT, and the potential founding of a spin-out company to commercialize digital printing of 2D materials. Aside from NTU and Graphenea, Other partners are Mellanox Technologies Ltd (Israel), Bar Ilan University (Israel), and Marios Lymarakis Kai Sia (Greece). The project is funded by the European Union under Grant agreement no 101058079.