Band gap engineering of the top layer of mica by organized defect formation

We report the narrowing of bandgap of the topmost layer of muscovite mica by low energy Ar+ ion beam induced defect formation. Variation of sputtering rate of the constituent elements of mica leads to organized defects creation. The first principle (DFT) calculation shows a bandgap of 4.63 eV for a single layer of muscovite mica, whereas the absence of specified atoms in that layer results in a reduction of bandgap to 1.3 eV. To examine the change of bandgap of a single mica layer, the top most layer of the muscovite mica is selected, and controlled atomic vacancies are created by low energy Ar+ ion sputtering at glancing angle. The bombarding ion energy and incidence angle are chosen by Monte Carlo Simulation (SRIM) to create the desired defects on the top most layer. Removal of the constituent atoms is probed by X-ray photoelectron spectroscopy and the change in bandgap is experimentally estimated by UV-Vis reflectance spectroscopy and conducting Atomic Force Microscopy (c-AFM). The experimental measurements of bandgap change are found to be consistent with the first principle calculation. The key features of bandgap alteration of the top layer of muscovite mica by ion induced sputtering are discussed.