Characterisation of silicon oxynitride thin films and their response to swift heavy-ion irradiation

Silicon oxynitrides (a-SiOxNy) are materials whose composition ranges between two binary materials: a-SiO2 and a-Si3N4. In this work, we present a systematic study of the fine structure of the damaged regions produced by swift heavy-ions (SHIs), or ‘ion-tracks’ and quantify the density variation profiles with respect to composition. Thin films were deposited by plasma-enhanced chemical vapor deposition (CVD), where thickness, density, stoichiometry and bond configuration were initially determined. The fine structure and radial size of the ion tracks was determined using small angle X-ray scattering. The tracks exhibit a core-shell cylindrical geometry, with an under-dense core surrounded by an over-dense shell with a smooth transition between the two regions. We observed two trends with composition: a constant increasing ion track radius is observed when the O/Si ratio is below one (0≤x≤1). And saturation of the radial dimensions above this value, being similar to a-SiO2. The IR spectra allowed to quantify the bond configuration and its evolution with fluence. After irradiation, the energy deposited by the SHI irradiation leads to a preferential damage of Si-N bonds. IR spectroscopy also showed the formation of new Si-H bonds with increasing fluences and resulting in a rather complex ion-induced structural modification of the a-SiOxNy network.

ChemFET sensor: Repercussion of Swift Heavy Ion irradiation on nanorods of nickel-based (NRs-Ni3HHTP2) Metal-Organic framework

Repercussion of Swift Heavy Ion (SHI) irradiation on nickel-based nanorods of Metal-Organic Framework (NRs-Ni3HHTP2-MOF) for enhancement in the properties of ChemFET based gas sensor has been investigated. Nanorods of Ni3HHTP2-MOF were synthesized by chemical method and exposed to C12+ ions irradiation with fluence 1x1011 ion/cm2 and 1x1012 ion/cm2. The structural, spectroscopic morphological and optical characterizations were carried out using x-ray diffraction (XRD), fourier transfer infrared spectroscopy (FTIR), atomic force microscopy (AFM) with scanning electron microscopy (SEM) and UV-visible spectroscopy were studied respectively. Whereas the bandgap was calculated from Tauc's plot. The synthesized nanorods of Ni3HHTP2 MOF were drop-casted on gold coated microelectrodes on silicon/silicon dioxide (Si/SiO2) substrate, where silicon layer serves as a gate and gold microelectrodes on silicon/silicon dioxide (Si/SiO2) substrate as a source and drain. The transmutations in material properties due to SHI irradiations were serviceable for enhancing field-effect transistor (transfer and output) properties.