Ambuj Tripathi

Engineering of electronic properties of single layer graphene by swift heavy ion irradiation

In this work, swift heavy ion irradiation induced effects on the electrical properties of single layer graphene are reported. The modulation in minimum conductivity point in graphene with in-situ electrical measurement during ion irradiation was studied. It is found that the resistance of graphene layer decreases at lower fluences up to 3 × 1011 ions/cm2, which is accompanied by the five-fold increase in electron and hole mobilities. The ion irradiation induced increase in electron and hole mobilities at lower fluence up to 1 × 1011 ions/cm2 is verified by separate Hall measurements on another irradiated graphene sample at the selected fluence. In contrast to the adverse effects of irradiation on the electrical properties of materials, we have found improvement in electrical mobility after irradiation. The increment in mobility is explained by considering the defect annealing in graphene after irradiation at a lower fluence regime. The modification in carrier density after irradiation is also observed. Ba...

New benchmark to improve the photoelectrochemical properties of hematite

Modification in the properties of material by swift heavy ion irradiation is an interesting area of research. It provides the researchers a new dimension of introducing desired changes to the behaviour of the material, which largely influence their PEC properties also. This communication describes a study on the swift heavy ion irradiation induced modification in the PEC properties of nanostructured hematite thin films. Thin films of nanostructured α-Fe2O3 prepared by spray-pyrolysis were irradiated with Si7+ ions at fluence ranging from 5x1012 to 4x1013 ions/cm2. After characterizing them for structural, morphological and optical parameters, photoelectrochemical response of the irradiated and unirradiated samples of hematite thin films in terms of photocurrent density as a function of different ions fluence, towards the solar splitting of water was studied. It was observed that ion fluence plays an important role in modifying the PEC properties of the material. Sample irradiated with 100 MeV Si7+ ions at fluence 2x1013 ions/cm2 exhibited the best photocurrent density.

Synthesis of graphene oxide thin film and effect of electron beam irradiation

Thin films of graphene oxide (or reduced graphene oxide) recently drawn a huge attention because of their several applications which are based on properties of graphene. The aim of the present paper is twofold: to find the straightforward, simple and cheap method for the preparation of thin film of graphene oxide and to study the effect of electron beam irradiation on the GO thin film. GO film was made by drop casting method from commercially procured aqueous solution of GO (concentration - 5 g/L). Electron beam irradiation were done in SEM obtain from MIRA II LMH from TESCAN. Irradiation of GO film was done at 25 keV electron beam energy. The authors have measured I-V characteristic of pristine as well as irradiated GO thin film in two probe configuration. Irradiation time were chosen 1 min, 33 min and 100 min which corresponds to 3×1011 e-/cm2, 1×1013 e-/cm2 and 3×1013 e-/cm2 fluence of electron beam. The samples were characterized using SEM and Raman methods. I-V spectra show that the resistance of fil...