Raman spectroscopy of gallium ion irradiated graphene

Abstract

The successful integration of graphene in future technologies, such as filtration and nanoelectronics, depends on the ability to introduce controlled nanostructured defects in graphene. In this work, Raman spectroscopy is used to investigate the induction of disorder in graphene via gallium ion beam bombardment. Two configurations of CVD-grown graphene samples are used: (i) graphene supported on a Si/SiO2 substrate, and (ii) graphene suspended on porous TEM grids. It is observed that the supported graphene experiences more damage in response to lower beam doses than suspended graphene. This phenomenon is attributed to the behaviour of the energetic ions impinging the sample. In suspended graphene, the ions pass through the graphene membrane once and disperse to the atmosphere, while in supported graphene, the ions embed themselves in the substrate causing swelling and backscattering events, hence increasing the induced disorder. In supported graphene, the ratio between the Gaussian D and G peaks attributed to amorphous carbon, and the Lorentzian D and G peaks attributed to graphene, (IDG/IDL) and (IGG/IGL), are suggested to be used to quantify the degree of amorphization. The results are relevant to the development of nanostructured graphene-based filtration or desalination membranes, as well as for graphene-based nanoelectronics.

Choosing a substrate for the ion irradiation of two-dimensional materials

“…The results presented above phenomenologically and qualitatively agree with other works published on the subject for graphene or 2D TMDs [1–3 6,30] and show the same energy regions of active substrate participation in the defect formation in 2D materials, as well as a similar scale and energy-dependent dynamics of the effect. However, the most useful comparison can be performed with the results given in a recent work [31] for graphene, where it underwent ion irradiation both when free-standing and supported with silicon.…”