Electron-beam induced nano-etching of suspended graphene

Abstract

Besides its interesting physical properties, graphene as a two-dimensional lattice of carbon atoms promises to realize devices with exceptional electronic properties, where freely suspended graphene without contact to any substrate is the ultimate, truly two-dimensional system. The practical realization of nano-devices from suspended graphene, however, relies heavily on finding a structuring method which is minimally invasive. Here, we report on the first electron beam-induced nano-etching of suspended graphene and demonstrate high-resolution etching down to ~7 nm for line-cuts into the monolayer graphene. We investigate the structural quality of the etched graphene layer using two-dimensional (2D) Raman maps and demonstrate its high electronic quality in a nano-device: A 25 nm-wide suspended graphene nanoribbon (GNR) that shows a transport gap with a corresponding energy of ~60 meV. This is an important step towards fast and reliable patterning of suspended graphene for future ballistic transport, nano-electronic and nano-mechanical devices.

Stability of suspended monolayer graphene membranes in alkaline environment

“…A second electron beam lithography step was used to create a rectangular opening in PMMA around the patterned graphene. This opening serves as a mask for underetching the SiO 2 and thus create an electrically contacted, suspended strip of graphene [37,38].…”

“…Finally, we show that suspended graphene, after being treated after KOH processing, can still be directly patterned using resist free nanofabrication techniques such as water assisted electron beam-induced etching (EBIE) [37]. EBIE is a technique based on the selective etching of graphene by selectively irradiating parts of the sample with a focused electron beam in the presence of a water vapor environment.…”

“…EBIE is a technique based on the selective etching of graphene by selectively irradiating parts of the sample with a focused electron beam in the presence of a water vapor environment. The combined effect of the electron beam and vapor adsorbate on graphene induces a chemical reaction which etches the irradiated parts of suspended graphene with a resolution of 7 nm [37]. To pattern the samples using this technique, we used an acceleration voltage V = 30 kV, a current I = 0.69 nA and a dose D = 10 μC/μm2.…”

Plasmon Resonances in a Periodic Square Coaxial Hole Array in a Graphene Sheet

“…2 is surrounded by the above dielectric, the A and S dips are located at 16.027 and 12.861 μm, respectively. In the practical fabrication process, we could start with CVD-grown graphene sheet transferred onto a dielectric substrate, then a square coaxial hole array may be fabricated in the graphene sheet using electron beaminduced nano-etching [37]. Finally, the sample is covered by a dielectric layer using atomic layer deposition.…”

Nanomanufacturing—Perspective and applications

“…Especially for graphene, a 2D lattice of carbon atoms is promising for building devices with exceptional electronic properties, where freely suspended graphene without contact with any substrate is the ultimate truly 2D system [8,181]. High-resolution room temperature nanoetching of suspended graphene layers into a graphene device is achieved by an electron beam [188].…”