Automatic graphene transfer system for improved material quality and efficiency

Abstract

In most applications based on chemical vapor deposition (CVD) graphene, the transfer from the growth to the target substrate is a critical step for the final device performance. Manual procedures are time consuming and depend on handling skills, whereas existing automatic roll-to-roll methods work well for flexible substrates but tend to induce mechanical damage in rigid ones. A new system that automatically transfers CVD graphene to an arbitrary target substrate has been developed. The process is based on the all-fluidic manipulation of the graphene to avoid mechanical damage, strain and contamination, and on the combination of capillary action and electrostatic repulsion between the graphene and its container to ensure a centered sample on top of the target substrate. The improved carrier mobility and yield of the automatically transferred graphene, as compared to that manually transferred, is demonstrated by the optical and electrical characterization of field-effect transistors fabricated on both materials. In particular, 70% higher mobility values, with a 30% decrease in the unintentional doping and a 10% strain reduction are achieved. The system has been developed for lab-scale transfer and proved to be scalable for industrial applications.

Parameter Space of Atomic Layer Deposition of Ultrathin Oxides on Graphene

“…The decrease in ω 2D and ω G modes toward lower wavenumbers indicates a decrease in the graphene doping level from ∼3 × 10 12 to ∼10 12 cm –2 when AlO x is introduced under CM at 80 °C, while the mechanical strain level remains similar in magnitude between −0.1 and −0.2% (Figure 5d). 51,52 On the other hand, when AlO x is deposited under SM at 200 °C, the doping level decreases further to <10 12 cm –2 and the mechanical strain level decreases slightly to between −0.05 and −0.15%, although the broadening in Γ 2D and Γ G indicates that the variation in the nanometer-scale strain is actually increased (Figure 5d). 53 It has been known that the presence of hydroxyl species on the SiO 2 surface induces the formation of charge trap sites that contribute to the doping level and the buckling behavior of G/SiO 2 .…”

Graphene Liquid Cells Assembled through Loop‐Assisted Transfer Method and Located with Correlated Light‐Electron Microscopy

“…We validate the LAT approach by comparison to two other GLC fabrication methods widely used in literature: the touch‐down method and the grid sandwich method. The three methods investigated in this paper (LAT, touch‐down and grid sandwich), require no lithographic substrate preparation or liquid handling equipment . Moreover, the methods were selected on the fact that the specimen liquid can be added as a macroscopic droplet, requiring no large volumes or micro‐spraying.…”

Demonstration of a New Technique for the Transfer Printing of Graphene on Photonic Devices

“…In order to exploit the promising properties of graphene in photonic integrated circuits a suitable transfer method should be developed. Several methods for the transfer of large scale graphene films have already been demonstrated [3,4], but limited work on the transfer of micron sized graphene films has been carried out and all proposed methods are derived from the manual wet transfer method [5,6].…”