Tanmay Mahanta | Searcharxiv

arXiv2022

Exploring the effect of varying regime of ion fluence on optical and surface electronic properties of CVD Grown Graphene

In this work, the effect of the ion fluence-dependent defect formation on the modification of surface electronic and optical properties of graphene has been investigated. The chemical vapor deposited (CVD) graphene was irradiated with swift heavy ion (SHI) (70 MeV Si+5) beam at different fluence to study the defect formation mechanism and the role of it in modulating its surface electronic property such as work function. At low ion dose, acceptor doping via vacancy creation was observed; whereas dense electronic excitation dominated extended defects was realized at higher dose, which subsequently transforms the crystalline graphene into amorphous carbon. The results from UV-Vis spectroscopy, Raman spectroscopy and scanning Kelvin probe microscopy (SKPM) support the fact. Thus a new pathway of transformation of graphene under SHI irradiation was explored where ion dose could be the main factor to realize several effects in graphene.

cond-mat.mtrl-sci↗

arXiv2021

Fermi Level Modulation of Boron Nitride Nanosheets by Vacancy Driven Compressive Strain

The compressive strain induced work function modulation in boron nitride nanosheets (BNNS) has been studied. The compressive strain arose due to the irradiation of 30 keV Au beam on thin films of BNNS. Before irradiation BNNS was characterized by Raman spectroscopy, UV-Vis spectroscopy, where using Tauc plot the bandgap of chemically synthesized BNNS from commercial hBN powder has been calculated as well as the layer numbers on thin films also quantified using an empirical relation exploiting the full width at half maxima (FWHM) of Raman peak of BNNS. The Scanning Electron Microscopy (SEM) images were also taken where layer like structure in pristine BNNS sample is visible and irradiation-induced changes in terms of irregular dots on BNNS samples is witnessed. The X-Ray Diffraction (XRD) was used to characterize the BNNS samples where peak corresponding to (002) plane is depicted as well as the peak shifting to higher angle which indicates the compressive strain in BNNS is also visible. Finally, the possible explanation of compressive strain formation by Au irradiation on BNNS was discussed using SRIM-2013 MC simulations. We've explained that vacancy induces strain in materials that lower the work function (WF). Scanning Kelvin Probe Microscopy (SKPM) was used to map the work function of the surface of BNNS, and it turned out that WF lowers with increasing dose of ions. The value of strain also calculated using the work function values and the results are qualitatively agreeing with the XRD results.

cond-mat.mtrl-sci↗