Post by williamplayer on Jan 15, 2015 15:19:12 GMT
Electron-Beam Induced Nano-Etching of Suspended Graphene
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. Graphene as a two-dimensional lattice of carbon atoms with its linear dispersion relation promises rich and interesting physical characteristics as well as devices with exceptional electronic properties, such as graphene-based transistors or electronic components which could be also based on ballistic transport. However, the presence of an underlying supporting substrate for the delicate single atomic layer is a major drawback as it decreases the envisioned high mobility by scattering, induced by potential fluctuations This limiting factor is particularly relevant for SiO as the commonly used supporting material and drives the search
for different materials, with hexagonal boron nitride (h-BN) presently being the most promising (but technically challenging) alternative. However, the ultimate, truly two-dimensional system is still a freely suspended graphene layer without contact to any substrate. The practical realization of nano-devices from suspended graphene, however, relies heavily on finding a structuring method which is minimally invasive and ensures an intact lattice structure.
Electron-beam lithography (EBL) followed by reactive ion etching is the most common technique for nano-patterning of supported graphene on insulating substrates into different structures like Hall-bar, nano-ribbons (GNR) or quantum dots. Resistless patterning techniques are an interesting alternative as they may reach higher resolution and are the only possible method for patterning suspended graphene, where the resist would otherwise damage the suspended structure. A focused ion-beam (FIB) provides an easy and fast method for graphene processing on the nanoscale using Ga-Ions or He-Ions. Although a resolution comparable to that of EBL can be achieved and it can be used for suspended graphene, the structural damage by energetic ion bombardment is a main drawback of FIB patterning.
READ FULL ARTICLE PDF: www.nature.com/srep/2015/150114/srep07781/pdf/srep07781.pdf
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. Graphene as a two-dimensional lattice of carbon atoms with its linear dispersion relation promises rich and interesting physical characteristics as well as devices with exceptional electronic properties, such as graphene-based transistors or electronic components which could be also based on ballistic transport. However, the presence of an underlying supporting substrate for the delicate single atomic layer is a major drawback as it decreases the envisioned high mobility by scattering, induced by potential fluctuations This limiting factor is particularly relevant for SiO as the commonly used supporting material and drives the search
for different materials, with hexagonal boron nitride (h-BN) presently being the most promising (but technically challenging) alternative. However, the ultimate, truly two-dimensional system is still a freely suspended graphene layer without contact to any substrate. The practical realization of nano-devices from suspended graphene, however, relies heavily on finding a structuring method which is minimally invasive and ensures an intact lattice structure.
Electron-beam lithography (EBL) followed by reactive ion etching is the most common technique for nano-patterning of supported graphene on insulating substrates into different structures like Hall-bar, nano-ribbons (GNR) or quantum dots. Resistless patterning techniques are an interesting alternative as they may reach higher resolution and are the only possible method for patterning suspended graphene, where the resist would otherwise damage the suspended structure. A focused ion-beam (FIB) provides an easy and fast method for graphene processing on the nanoscale using Ga-Ions or He-Ions. Although a resolution comparable to that of EBL can be achieved and it can be used for suspended graphene, the structural damage by energetic ion bombardment is a main drawback of FIB patterning.
READ FULL ARTICLE PDF: www.nature.com/srep/2015/150114/srep07781/pdf/srep07781.pdf