Residual Metallic Contamination of Transferred Chemical Vapor Deposited Graphene

Abstract

Integration of graphene with Si microelectronics is very appealing by offering a potentially broad range of new functionalities. New materials to be integrated with the Si platform must conform to stringent purity standards. Here, we investigate graphene layers grown on copper foils by chemical vapor deposition and transferred to silicon wafers by wet etching and electrochemical delamination methods with respect to residual submonolayer metallic contaminations. Regardless of the transfer method and associated cleaning scheme, time-of-flight secondary ion mass spectrometry and total reflection X-ray fluorescence measurements indicate that the graphene sheets are contaminated with residual metals (copper, iron) with a concentration exceeding 10(13) atoms/cm(2). These metal impurities appear to be partially mobile upon thermal treatment, as shown by depth profiling and reduction of the minority charge carrier diffusion length in the silicon substrate. As residual metallic impurities can significantly alter electronic and electrochemical properties of graphene and can severely impede the process of integration with silicon microelectronics, these results reveal that further progress in synthesis, handling, and cleaning of graphene is required to advance electronic and optoelectronic applications.

Plasma-enhanced chemical vapor deposition of amorphous Si on graphene

“…We associate this striking difference with reduced ion energy in VHF plasmas 13 and resulting significantly lower amount of bombardment-related defects in the hexagonal network of sp Commercially available graphene on Cu foils was transferred onto 100 nm SiO 2 substrates using wet etch transfer technique. 17,18 All graphene samples (1cm x 1cm) for both RF PECVD and VHF PECVD were cut from the same piece of 5cm x 5cm-large graphene/Cu foil to ensure a fair comparison between both methods. Before Si deposition samples were annealed in UHV at 400°C for 20 min to remove residual polymer used as a support in the transfer process.…”

Contamination-Free Graphene Transfer from Cu-Foil and Cu-Thin-Film/Sapphire

“…As shown in Figure 2a have a considerably smaller amount of backside graphene residue which can trap the metal catalyst between transferred graphene film and backside graphene flake. Although not all metal residues can be eliminated with this method because the metal residues can exist not only at trapped surface but also at any other morphological feature such as grain boundaries, wrinkles, graphene adlayer, etc., it can be relatively reduced [24]. Additional research is needed to eliminate them.…”

“…Although not all metal residues can be eliminated with this method because the metal residues can exist not only at trapped surface but also at any other morphological feature such as grain boundaries, wrinkles, graphene adlayer, etc., it can be relatively reduced [24]. Additional research is needed to eliminate them.…”

Comparative Morphological Analysis of Graphene on Copper Substrate obtained by CVD from a Liquid Precursor

“…The obtained Cu sheets with graphene layers were placed and stored in argon atmosphere. In a separate experiment, graphene deposition on Cu from methane was carried out according to procedure described in the work [29]. …”