Abstract
The effect of ion-induced defects on graphene was studied to investigate the contact resistance of 40 nm palladium (Pd) contacting on graphene. The defect development was considered and analyzed by irradiating boron (B), carbon (C), nitrogen (N2), and argon (Ar) ions on as-transferred graphene before metallization. The bombardment energy was set at 1.5 keV and ion dose at 1 × 1014 ions/cm2. The defect yields under different ion irradiation conditions were examined by Raman spectroscopy. Although, dissolution process occurs spontaneously upon metal deposition, chemical reaction between metal and graphene is more pronounced at higher temperatures. The rapid thermal annealing (RTA) treatment was performed to improve the Pd/graphene contact after annealing at 450 °C, 500 °C, 550 °C, and 600 °C. The lowest contact resistance of 95.2 Ω-µm was achieved at 550 °C RTA with Ar ion irradiation. We have proved that ion irradiation significantly enhance the Pd/graphene contact instead of pd/pristine graphene contact. Therefore, in view of the contention of results ion induced defects before metallization plus the RTA served an excellent purpose to reduce the contact resistance.
Highlights
Graphene has been studied lately during the course of establishing high-speed radiofrequency devices, interconnects [1], photonics [2,3], and flexible electronics [4]
With the absence of D peak in the spectrum, the intensity ratio and sharpness of 2D and G peaks describe the clean transfer of monolayer graphene sheet to the substrate and absence of induced observable defects
D-band signal confirms transfer process was carried out successfully with a smaller number of defects. This does attest the fact that the defect evolution started after ion irradiation on to the surface of transferred graphene
Summary
Graphene has been studied lately during the course of establishing high-speed radiofrequency devices, interconnects [1], photonics [2,3], and flexible electronics [4]. The main hindrance is the reported contact resistance for graphene compared to silicon devices. In order to reduce the contact resistance, different methods have been used, ranging from the cleaning the graphene surface to the use of different metals and annealing at different temperatures. In order to improve the carrier transmittance and reduce contact resistivity, it is necessary to study the monoatomic graphene layer, which is completely different from typical silicon junctions. The contact resistance (Rc ) values are currently determined by the chemical bonds, interface engineering, and electronic structure of graphene. The challenge which poses a barrier towards integration and reduction of graphene electronic devices is the reproducible formation of low contact resistance. Conventional deposition of metal electrodes on top of the graphene surface often resulted in a large contact resistance [5,6,7].
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