High current limits in chemical vapor deposited graphene spintronic devices

Abstract

Understanding the stability and current-carrying capacity of graphene spintronic devices is key to their applications in graphene channel-based spin current sensors, spin-torque oscillators, and potential spin-integrated circuits. However, despite the demonstrated high current densities in exfoliated graphene, the current-carrying capacity of large-scale chemical vapor deposited (CVD) graphene is not established. Particularly, the grainy nature of chemical vapor deposited graphene and the presence of a tunnel barrier in CVD graphene spin devices pose questions about the stability of high current electrical spin injection. In this work, we observe that despite structural imperfections, CVD graphene sustains remarkably highest currents of 5.2 × 108 A/cm2, up to two orders higher than previously reported values in multilayer CVD graphene, with the capacity primarily dependent upon the sheet resistance of graphene. Furthermore, we notice a reversible regime, up to which CVD graphene can be operated without degradation with operating currents as high as 108 A/cm2, significantly high and durable over long time of operation with spin valve signals observed up to such high current densities. At the same time, the tunnel barrier resistance can be modified by the application of high currents. Our results demonstrate the robustness of large-scale CVD graphene and bring fresh insights for engineering and harnessing pure spin currents for innovative device applications.

Large-Scale Direct Growth of Monolayer MoS2 on Patterned Graphene for van der Waals Ultrafast Photoactive Circuits

“…For standardizing the experimental observations and scalability of quantum and spin transport for practical applications, large-scale 2D material growth is of primordial importance. In this context, significant developments have been performed regarding the growth and testing of the performance of large-scale chemical vapor-deposited materials. − Various 2D materials have been successfully grown, including graphene and 2D semiconductors such as MoS 2 , WS 2 , and 2D magnets. − Despite these, state-of-the-art reports of heterostructures predominantly rely on wet or dry transfer methods, both of which result in polymer residues at the interfaces that impact the longevity and device performance. The CVD growth of heterostructures remains challenging due to the complex surface physics, extremely small grain size, lack of monolayer growth, and problems achieving efficient interlayer coupling and charge transfer. − To ensure the reliability and scalability of such applications, there is a need to establish direct growth methods for 2D material heterolayers with optimal interfaces.…”

“…In this context, significant developments have been performed regarding the growth and testing of the performance of large-scale chemical vapor-deposited materials. 14 − 17 Various 2D materials have been successfully grown, including graphene and 2D semiconductors such as MoS 2 , WS 2 , and 2D magnets. 17 − 20 Despite these, state-of-the-art reports of heterostructures predominantly rely on wet or dry transfer methods, both of which result in polymer residues at the interfaces that impact the longevity and device performance.…”

Laser‐Induced Graphene Electrodes for Organic Electrochemical Transistors (OECTs)

“…This is due to the fact that laser-induced graphene has a much larger thickness than single or multilayer CVD graphene on the order of micrometers. [30,33] Within LIG flakes, a high degree of graphitization allows for an efficient transport of charge carriers, but conductivity is limited by transport between flakes. By tailoring the laser settings, it is possible to alter the conductivity and porosity of graphene for a variety of uses.…”