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In this paper, the effects of annealing temperature on HfO2 thin films prepared by RF sputtering have been investigated. Thin films of hafnium oxide were deposited using sputtering onto p-type Si substrates and the pristine films were annealed at different temperatures in air atmosphere to obtain crystallinity. The Raman and XRD results of the as-deposited films show amorphous nature, whereas the annealed films at 600 °C results in crystallization. AFM was used to study the surface morphology of the films and to estimate the skewness, kurtosis and the roughness values. The core level orbitals of Hf 4f spectra of as-deposited films not only reveal the formation of hafnium rich hafnium oxide but also nearly stoichiometric composition of HfO2 and exhibit a shift in binding energy with annealing. Electrical measurements of the films suggest that the leakage current is increased for crystalline films as compared to the as-deposited ones. The effects of annealing temperature on quality and stoichiometry of hafnia thin films and their possible applications are reported.

In this paper, we demonstrate the fabrication and charge storage characteristics of Au nanocrystals located between two hafnium oxide films acting as the tunneling and blocking layers serving as nonvolatile memory structure. The structure, composition and electrical properties of the device are drastically affected by annealing temperature. The inter-diffusion and stoichiometric changes of various layers are investigated using X-ray Photoelectron Spectroscopy and Rutherford Backscattering Spectroscopy. Electrical measurements show an improvement in leakage characteristics with annealing. The C-V hysteresis loop with and without Au nanocrystals are compared to understand charge storage behavior of the device structures. The occurrence of well-defined hysteresis loop with Au nanocrystals indicates significant role of Au nanocrystals in charge storage characteristics of the device.

We report the structural and optical properties of high-energy ion-beam irradiated Co-doped magnesium titanate thin films. (Mg0.95Co0.05)TiO3 (MCT) thin films were deposited on quartz substrates us...

In the present study, the effects of swift heavy ion induced modification on the structural, morphological and optical properties of potassium sodium niobate (KNN) thin films have been investigated. KNN thin films were deposited using RF magnetron sputtering onto Si and quartz substrates. Subsequently, as-deposited films were annealed at 700 °C in air ambience for crystallization. Eventually, these crystalline films were irradiated using 100 MeV Ag ions at various fluences ranging from 1 × 1012 to 1 × 1013 ions/cm2. The crystalline and irradiated films were characterized using various techniques such as X-ray diffraction (XRD), atomic force microscopy (AFM), Raman spectroscopy, and UV–Vis spectroscopy. XRD results reveal that the crystallinity of films decreases drastically upon irradiation and almost disappeared at 1 × 1013 ions/cm2. Raman spectra show the different vibration modes of NbO6 octahedra. Raman peaks intensity is decreased and the peaks get broadened due to irradiation which indicates the amorphous nature of films. Variation in surface morphology and roughness of films before and after irradiation is studied using AFM. The minimum value of roughness is observed at 5 × 1012 ions/cm2. Ion beam irradiation results in the variation of transmittance and optical band gap of the films. The optical band gap of crystalline KNN film is found to be 3.82 eV which decreased to 3.72 eV upon irradiation at 5 × 1012 ions/cm2. The monotonous decrease in the refractive index and packing density of films is also observed with ion fluence.

MgTiO3 thin films were deposited on an amorphous silicon dioxide substrate by the RF magnetron sputtering method by varying the argon and oxygen mixing percentage. These pristine thin films were subjected to thermal annealing at a temperature of 700°C and subsequently two sets of crystalline thin films were irradiated using 100 MeV Au8+ ions at a fixed fluence of 2 × 1013 ions/cm2. XRD spectra reveal that the crystallite size reduces from 21 to 15 nm and crystallinity also decreases drastically after irradiation. AFM images show significant variation in the surface morphology upon irradiation. Optical studies suggest that the band gap as well as the refractive index are both reduced due to SHI irradiation. Ion beam induced modification of the structural, morphological and optical properties of MgTiO3 thin films and the possible mechanisms responsible for variation of the properties of MgTiO3 due to swift heavy ion beam irradiation have been discussed in detail.

In this work, the effects of annealing temperature on the compositional, morphological and electrical properties of SiO2/Au/SiO2 trilayer structure are investigated. SiO2 and Au layers were deposited using RF magnetron sputtering and e-beam evaporation techniques, respectively. Transmission electron microscopic images reveal the formation of Au nanocrystals. Atomic force micrographs show the variation in surface roughness with annealing temperature. Rutherford backscattering spectroscopy was employed to estimate the thickness of the trilayer structure. X-ray photoelectron spectroscopy results indicate the formation of Au nanocrystal and SiO2 tunneling and blocking layers. The hysteresis curve indicates the role of Au nanocrystals in charge storage characteristics of the device structure.

High energy heavy ion irradiation-induced modification of high quality crystalline GeO2 thin films grown at different substrate temperatures ranging from 100 to 500 °C using pulsed laser deposition has been investigated. The pristine films were irradiated with 100 MeV Ag7+ ions at fixed fluence of 1 × 1013 ions/cm2. These pristine and irradiated films have been characterized using X-ray diffraction, atomic force microscopy, Raman spectroscopy, Fourier transform infrared and photoluminescence spectroscopy. The XRD and Raman results of pristine films confirm the formation of hexagonal structure of GeO2 films, whereas the irradiation eliminates all the peaks except major GeO2 peak of (101) plane. It is evident from the XRD results that crystallite size changes with substrate temperature and SHI irradiation. The surface morphology of films was studied by AFM. The functional group of pristine and irradiated films was investigated by IR transmission spectra. Pristine films exhibited strong photoluminescence around 342 and 470 nm due to oxygen defects and a red shift in the PL bands is observed after irradiation. Possible mechanism of tuning structural and optical properties of pristine as well as irradiated GeO2 films with substrate temperature and ion beam irradiation has been reported in detail.