Lift-Off Assisted Patterning of Few Layers Graphene

Abstract

Graphene and 2D materials have been exploited in a growing number of applications and the quality of the deposited layer has been found to be a critical issue for the functionality of the developed devices. Particularly, Chemical Vapor Deposition (CVD) of high quality graphene should be preserved without defects also in the subsequent processes of transferring and patterning. In this work, a lift-off assisted patterning process of Few Layer Graphene (FLG) has been developed to obtain a significant simplification of the whole transferring method and a conformal growth on micrometre size features. The process is based on the lift-off of the catalyst seed layer prior to the FLG deposition. Starting from a SiO2 finished Silicon substrate, a photolithographic step has been carried out to define the micro patterns, then an evaporation of Pt thin film on Al2O3 adhesion layer has been performed. Subsequently, the Pt/Al2O3 lift-off step has been attained using a dimethyl sulfoxide (DMSO) bath. The FLG was grown directly on the patterned Pt seed layer by Chemical Vapor Deposition (CVD). Raman spectroscopy was applied on the patterned area in order to investigate the quality of the obtained graphene. Following the novel lift-off assisted patterning technique a minimization of the de-wetting phenomenon for temperatures up to 1000 °C was achieved and micropatterns, down to 10 µm, were easily covered with a high quality FLG.

Sensitive Transfer-Free Wafer-Scale Graphene Microphones

“…The graphene on Mo is exposed for 40 min at 65 °C with a final low-power ultrasonic bath of 90 s to strip the cross-linked photoresist (PR). Intercalation of NMP into the stacked layers and the short ultrasonic bath have probably negatively affected the quality of the material, as already reported in other works. − We exclude that the DRIE is invasive since the graphene is not exposed to the plasma etch from the backside of the wafer and instead faces the tool’s chuck. VHF is also not considered a possible defective source because the I D / I G ratio does not show any significant change after the release (Figure b).…”

Scaling Organic Electrochemical Transistors Down to Nanosized Channels

“…Traditional adhesion layer metals, such as Ti or Cr, should be avoided since they negatively affect the EIBJ shunting the controlled electromigration in the main electrical path along the narrow Au microwire, while Al 2 O 3 acts both as a proper adhesion layer and insulator for the EIBJ process. The use of Al 2 O 3 ensures an optimal adhesion, which is peculiar for this application, as for other specific applications, since the induced electromigration can result in a delamination of the whole Au film. The Au patterning was performed by photolithography (with AZ 1518 photoresist) and wet etch processes employing a KI/I 2 solution (KI:I 2 :H 2 O = 4 g:1 g:40 mL).…”

Dynamically Tunable Phase Shifter with Commercial Graphene Nanoplatelets

“…Due to its interesting properties graphene has caught significant attention [4]. Not only has graphene been studied in its original form but also for functionalization and patterning [5,6]. One of the most popular deposition methods of carbon based materials is their deposition as films [7,8].…”