Laser printing of Graphene & 2DM
Graphene Field Effect Transistors by LIFT
NTUA has demonstrated the versatility of Laser Induced Transfer by reporting results on the high-quality digital transfer of graphene and MoS2, in the frame of the EIC-Transition project “L2D2”. 2D materials have emerged in the field of nanoelectronics, sensors and photonics due to their unique optoelectronic properties, but their high-quality transfer remains a hurdle. The quality of the transferred films has been confirmed with systematic characterization based on Scanning Electron Microscopy and Raman spectroscopy, as well as mobility’s extraction. Then we will present how the laser induced transfer of these materials can be employed as a key-enabler for the demonstration of the digital deposition of graphene and MoS2 pixels with form factors and electronic properties suitable for FETs. The presented results highlight the potential of LIT for the wafer scale integration of 2D materials, therefore fostering the wider industrial incorporation of 2D materials in electronics, optoelectronics and photonics.
We have presented [1] the successful deposition of graphene, through the Laser-Induced Transfer technique, as the channel into a Field-Effect Transistor (FET) configuration. Following the process described so far (fluence, reduced pressure, contact of the substrates), the graphene was printed on a SiO2/Si substrate, on a patterned surface with already formed electrode structures composed of Pt, as the source and drain of the FET (Figure (a)). More specifically, Graphene FETs were created with four different channel lengths (20 μm, 10 μm, 4 μm and 3 μm). The purpose was to study the electrical properties of laser-induced transferred graphene, as well as to derive a value for the mobility of the transferred pixels. The FET substrate consisted of a Si-doped back gate, 300 nm SiO2 as gate dielectric and on the back side a platinum metal contact. Figure (b) shows the schematic representation of the FET structure, while Figure (c) shows an optical microscope photo of the resulting device. Arrays of 150 µm x 150 µm, consisting of 16 pixels were formed using LIT, in order to cover as much surface as possible.
[1] I.Cheliotis, A. Logotheti, F. Zacharatos, A. Pesquera, A. Zurutuza, D. Naveh, L. Tsetseris, and I. Zergioti "Laser induced transfer of 2D materials for optoelectronic applications", Proc. SPIE 12410, Nanoscale and Quantum Materials: From Synthesis and Laser Processing to Applications 2023, 1241004 (15 March 2023);
https://doi.org/10.1117/12.2648065
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Laser Direct Transfer of Graphene on Si and PDMS
NTUA’s team has demonstrated the controllable Laser Direct Transfer of Graphene for the formation of arrays with resolution in the order of 50 μm on Si and PDMS substrates in the recently published article [1], in the frame of the H2020-FET-open project “Leaf-2D”. Using LIFT, CVD graphene pixels of 30 μm x 30 μm in size were transferred on SiO2/Si and flexible polymer (PDMS) substrates. The potential of upscaling this novel approach by reaching sizes of up to 300 μm x 300 μm for transferred graphene patches is also demonstrated. As can be seen in Figure 1, Raman color mapping and SEM characterization, revealed that LIFT can enable, in a reproducible manner, the seamless ejection of a graphene monolayer and its attachment on a receiving SiO2/Si or polymer substrate.
Figure 1. Laser printing of single layer CVD graphene on SiO2/Si and PDMS and Raman color map of the printed graphene pixels. (a) Optical microscopy image of a laser printed graphene array on SiO2/Si, (b) SEM image of graphene pixel highlighted in red in (a), (c) Optical microscopy image of 4 graphene arrays printed on PDMS and comprising 10x10 graphene pixels each, (d) Raman color map of I2D/IG peak intensity ratio within a single graphene pixel printed on SiO2/Si (pixel 10 in (e)), (e) Raman spectra of 10 distinct laser printed graphene pixels on SiO2/Si.
NTUA has thus demonstrated the capacity of the LIFT technique to achieve the selective, defect-free and digital transfer of CVD-grown graphene without the need for post-printing processing steps.
Ref. [1] "A direct transfer solution for digital laser printing of CVD graphene”, Symeon Papazoglou, Dimitrios Kaltsas, Adamantia Logotheti, Amaia Pesquera, Amaia Zurutuza, Leonidas Tsetseris and Ioanna Zergioti, in 2D Materials, 8(4), 045017, (2021)
This project has received funding from the European Union’s Horizon 2020 research and innovation programme
under grant agreement No 801389.
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