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A facile method for direct and selective area conversion of 4H-SiC substrates into homogeneous epitaxial graphene is demonstrated by the irradiation of a low energy (5 keV) electron beam (e-beam). The localized interactions like scattering, excitation, and ionization between the primary electrons and the SiC surface result in Si−C bond breaking, and the excess kinetic energy of electrons is dissipated as heat that results in the selective sublimation of the Si ion favoring the formation of epitaxial graphene. The thickness of the graphene layer is precisely controlled by varying the e-beam energy and the irradiation time. The number of graphene layers increases with irradiation due to thermally induced Si sublimation over the depth of a few atomic layers depending on the incident energy of the e-beam. The Hall mobility of large area single layer graphene formed on the Si-face is ∼6450 cm 2 V −1 s −1 with a surface carrier density (n-type) of 1.5 × 10 13 cm −2 . Our results demonstrate that the e-beam irradiation technique is a viable route to define wafer scalable selective area graphene structures directly on semi-insulating 4H-SiC substrates for electronic applications.

Niobium (Nb) doping (0 at.% to 3 at.%) in ZnO thin films prepared by the chemical spray pyrolysis method at a substrate temperature of 400°C enhances the optical and electrical properties but deteriorates the structural quality of the films. The films are polycrystalline with hexagonal structure having a preferential orientation along the (002) crystallographic direction. The film doped with 3 at.% Nb demonstrates a maximum average transmittance of $83% in the visible region. A strong blue emission is recorded for both pure and doped films, and the intensity is substantially enhanced with Nb doping due to interface and valence-band transitions. Vacuum annealing at 400°C for 60 min improves the electrical characteristics of the films, and the highest mobility of 71 cm 2 /V s is achieved for the 1 at.% Nb-doped ZnO films.