RF Sputtering Deposition Technique Research Articles

Impact of Ag and Au Metal Contacts on WO3 Nanowires for High Performance Photodetection

In this article two different junction devices Ag/WO3 NW/p-Si (p-n junction) and Au/WO3 NW/n-Si (Schottky junction) were contrived under glancing angle deposition (GLAD) induced RF sputtering deposition technique. The FE-SEM (field-emission scanning electron microscopy) and TEM (transmitted electron microscopy) characteristics confirmed the growth of WO3 nanowires (NWs) array of length ~110 nm and diameter of ~45 nm. Moreover, from the I-V characteristics curve the formation of a good Schottky and p-n junction was confirmed with a high rectification ratio (RR) value of 370 and 2208 respectively. The specific detectivity (D*) and noise equivalent power (NEP) of the photodetector (PD) device were found to be <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.88\times 10^{10}$ </tex-math></inline-formula> Jones, 0.0572 nW and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.48\times 10^{9}$ </tex-math></inline-formula> Jones, 0.614 nW for Ag/WO3 NWs/p-Si and Au/WO3 NW/n-Si respectively. Furthermore, the device showed fast response with rise and fall time of 6.1 ms, 6.7 ms for Ag/WO3 NW/p-Si and 10 ms, 10.3 ms for Au/WO3 NW/n-Si respectively.

Bottom gate ZnO-TiO2 thin film transistor fabrication using a Rf-sputtering technique on Si and glass substrates

ZnO thin films were fabricated by an RF-sputtering deposition technique on Si and Glass substrate and then was used as the active semiconductor material in thin-film transistors (TFTs). The TFTs were fabricated in a bottom gate with top contact electrode structure with high-k TiO2 as the gate insulator and Au used for the source and drain electrodes but Al for the gate electrode. TFTs were annealed at 500 °C for 1 h using sputtering inside the substrate heating facility. The TFT with a W/L (4/1) channel ratio found high field-effect mobility of is 5.19 cm 2 /Vs and drain current on–off ratio at 10 7 with a low threshold voltage.

Study of humidity sensing properties and ion beam induced modifications in SnO2-TiO2 nanocomposite thin films

Swift heavy ion beam induced dense electronic excitation in the nanocomposite thin film is a unique way to introduce various modifications such as track formation, atomic transport and phase transformation. Therefore, this work based on the modification in the properties of Titanium dioxide and Tin oxide nanocomposite thin films prepared by RF sputtering deposition technique in the mol% 50:50 on ITO coated glass and silicon substrates. The prepared nanocomposite thin films annealed at 500 °C and irradiated with SHI of 150 MeV Fe11+ ion beam with varied ion fluences ranging from 5 × 1012to 5 × 1013 ions.cm−2. The SRIM simulation was confirmed the electronic energy loss (Se) as 1.038 × 102 eV/nm, nuclear energy loss (Sn) as 1.33 × 10−1 eV/nm and the projectile depth of the iron ion inside the thin films was founded to be 17.18 um. Structural analyses of pristine and irradiated thin films were analyzed by X-ray diffraction technique. Changes observed in the peak intensity were confirmed by the significant variations in crystallite size, which was calculated by the Debye Scherrer equation. The crystallite size of all samples was found to be improved from 59 nm to 141 nm. The influence of ion irradiation on surface topography of nanocomposite thin films was analyzed by Atomic Force Microscopy (AFM). The sectional analysis of AFM images reveals that the grain size depends on the ion irradiation fluences. The grain size was increased from 52 nm to 129 nm. The optical properties were studied using UV–Visible spectroscopy and Photoluminescence (PL) spectroscopy. Tauc's method was used to calculate the optical energy band gap of the samples. The direct band gap was decreased as ion fluence increases may be due to creation of metastable energy states in between the valance and conduction band. The recombination and separation of photo generated charge carriers were studied by the photoluminescence spectroscopy. Rutherford Backscattering Spectrometry (RBS) was performed on all samples to ensure depth profiling, elemental composition and absence of impurities in titanium dioxide and tin oxide nanocomposite thin films. The response time, recovery time, repeatability and ageing effect after (one, two and three) weeks of nanocomposite thin films were obtained during humidity sensing measurements.

Low energy Kr5+ ion beam engineering in the optical, structural, surface morphological and electrical properties of RF sputtered TiO2 thin films

Titanium dioxide (TiO2) thin films were grown on Silicon and glass substrates at room temperature by RF sputtering deposition technique. All deposited thin films were irradiated by 800 keV Kr5+ low energy ion beam with varying ion fluence from 1E15 ions/cm2 to 1E17 ions/cm2. The decreases in crystallite size from 42.09 nm to 27.36 nm (by Scherrer's formula) with increased in ion fluence were observedusing X-ray Diffraction (XRD) technique. The orientation of the different planes was observed but the plane (112) confirmed the preferred orientation as determined by the texture coefficient using XRD patterns. The surface morphology of the samples was studied by Atomic Force Microscopy (AFM) technique in the tapping mode and the Root Mean Square (RMS) roughness (Rq) was found to be increased from 0.739 nm to 3.20 nm with increases the ion fluence. The energy bandgap was found to be increased from 4.06 eV to 4.30 eV by increased in ion fluence due to electron confinement at nano-scale and also observed Urbach energy and optical conductivity by UV–Visible spectroscopy. The Urbach energy of thin films was observed to increased with increasing the ion fluence. The photoluminescence (PL) spectra confirmed the enhancement in the recombination of electron hole pair with increases the oxygen vacancies by increases the ion fluence. The peak at 382 nm was observed at higher fluence of 7E15 ions/cm2, 3E16 ions/cm2 and 1E17 ions/cm2. In the Raman studies, all six Raman modes at their positions for anatase phase of TiO2 thin films were successfully observed. The thickness of thin films was observed 268 nm and elemental composition of titanium and oxygen in all thin films were confirmed in the ratio of 1:2 by using Rutherford Backscattering Spectrometry (RBS). The electrical properties were studied by measuring the variation of current (I) with respect to the applied potential (V) at room temperature and the conductivity of the irradiated thin films was decreased with increases of ion fluence.

Influence of 120 MeV S9+ ion irradiation on structural, optical and morphological properties of zirconium oxide thin films deposited by RF sputtering

The calibrated and controlled swift heavy ions (SHI) beam irradiation generate defects which can cause modifications in various properties of the materials such as structural, optical, magnetic, morphological, and chemical etc. The passage of ion through the target material causes the nuclear energy losses (Sn) and electronic energy losses (Se). The Se dominates over Sn in SHI irradiation. In the present study, ZrO2 thin films were grown on silicon and glass substrate by using RF sputtering deposition technique. For the purpose of modifications induced by swift heavy ions, these films were irradiated by a 120 MeV S9+ ion beam of 1 pnA current, with varying ion fluences from 5E12 to 1E13 ions/cm2, using the tandem accelerator at the Inter University Accelerator Center (IUAC), New Delhi, India. The X-ray diffraction (XRD) patterns confirmed the formation of monoclinic and tetragonal phases and it was observed that XRD peaks intensity increased up to the fluence of 5E12 ions/cm2 followed by opposite behavior at higher fluences. Atomic force microscope (AFM) study revealed the increased surface roughness after SHI irradiation. In addition to it, the formation of electronic transition states in optical band gap region and enhancement of absorption edge was observed from UV-visible spectroscopy (UV-Vis) results due to which direct band gap energy value decreased from those of un-irradiated samples. Photoluminescence (PL) broad emission spectra were determined using the excitation wavelength at 290 nm with the prominent peak at 415 nm which can be ascribed to Zr vacancies due to band edge emission as a result of free-exciton recombination. Rutherford backscattering spectrometry (RBS) technique was used for depth profiling and elemental composition in zirconia thin films. The expected role of electronic energy loss during ion irradiation is to modify the properties of the material has been discussed.

Effect of low energy (keV) ion irradiation on structural, optical and morphological properties of SnO2–TiO2 nanocomposite thin films

RF Sputtering deposition technique was used to deposit the thin films of nanocomposite oxides as SnO2–TiO2 on Si and ITO coated glass substrate. As a target, SnO2–TiO2 was taken according to their molecular weight percent ratio of 3:1. Material modification has been induced by low energy ion beam with varying ion fluence from 5E13 to 5E16 ions/cm2. Glancing Angle X-ray Diffraction technique was used to study crystallite size, phase transformation and stability of different planes of pristine and irradiated thin films. The important peaks observed in XRD pattern were at angles 26.95°, 34.27°, 37.60°, 50.88° and 52.46°. The grain size distribution and surface morphology were studied by Atomic Force Microscopy technique in tapping mode. The results show that the grain size varies with ion fluence. Raman analysis revealed that the sharp peak at the frequency of 520 cm−1 ascribed to the T2g mode was observed for the pristine and lowest fluence irradiated film deposited on Si substrate. With increasing ion fluence, an opposite trend in SnO2 B2g peak was observed at nearly 775 cm−1 and the also peak bump was observed as a function of ion beam fluence. The optical band gap decreases from 3.90 to 3.63 eV due to the generation of ions and free radicals in valance band by varying ion fluence which was observed by UV/Visible Spectroscopy. The film thickness was determined to be 220 nm using Rutherford Backscattering Spectrometry. It also confirmed the absence of any impurities in the pristine and irradiated thin films. The material properties were mainly modified by the point defects and grain size growth arising due to nuclear energy loss.

Effect of UV-Ozone Treatment on the Performance of ZnO TFTs Fabricated by RF Sputtering Deposition Technique

In this paper, bottom-gate thin-film transistors (TFTs) with zinc oxide (ZnO) channels were grown on Si substrates with an SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> dielectric layer via the radio-frequency sputtering technique. The ZnO films were then subjected to 16 min of ultraviolet (UV)-ozone treatment, which resulted in fewer oxygen vacancies, enhanced crystallization, lower strain, lower surface roughness, and higher thin-film density, as well as improved surface energy and adhesion properties of the gallium zinc oxide source/drain electrodes. The UV-ozone 16-min ZnO active layer TFT with the preferable resistivity values by Hall measurement results. The optimal UV-ozone treatment time (16 min) led to the smallest full-width at half-maximum (0.4138°), smallest strain (2.61 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> ), highest thin-film density (5.78 g/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ), lowest surface roughness (1.75 nm), and largest surface energy (65.3 mJ/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ). The saturation mobility, subthreshold voltage, ON/OFF current ratio, and trap density of the ZnO TFTs with optimal UV-ozone treatment were 4.54 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> S <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , 0.28 V/decade, 2.02 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> , and 2.61 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> eV <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> , respectively, indicating the potential of this structure to be applied to large-area flat-panel displays.

Chromium Nanowires Grown Inside Lithographically Fabricated U-Trench Templates

Chromium nanowires of diameter 40-120 nm have been grown inside lithographically fabricated U-trench templates on oxidized silicon substrate by RF sputtering deposition technique. Under favourable experimental conditions, very long nanowires can be grown which depends on the trench length and surface homogeneity along the axis. Surface wettability control by the restricted supply of metal vapour is the key for the formation of nanowires. Diameter/depth ratio for the trench template is demonstrated to be crucial for the growth of nanowires.

Angular dependence of dynamic magnetic properties and magnetization orientation distribution of thin films

The angular dependence of dynamic magnetic properties of FeTaN thin films fabricated by rf sputtering deposition technique onto various substrates was investigated in conjunction with static magnetic characteristics. Thin films grown onto rigid and thick substrates show a well-defined uniaxial anisotropy and strongly distinct permeability spectra measured at various orientations while those samples grown onto flexible and thin substrates exhibit a less well-defined uniaxial anisotropy and much less different permeability spectra. The resultant variation of the magnetization orientation distributions obtained by retrieving the magnetization values from the permeability curves for different substrates can be interpreted in terms of the magnetic anisotropy dispersion due to stress.

Ferroelectric and Dielectric Properties of Pb(Mg1/3Ta2/3)0.7Ti0.3O3 Thin Films Derived from RF Magnetron Sputtering

Pb(Mg1/3Ta2/3)0.7Ti0.3O3 thin films of single perovskite phase were successfully synthesized by using the RF sputtering deposition technique, followed by post-thermal annealing. While the perovskite structure of Pb(Mg1/3Ta2/3)0.7Ti0.3O3 is rather unstable, phase evolution in the thin films was manipulated by controlling both working pressure during the sputtering process and post-thermal annealing temperature. The desirable perovskite phase was promoted by increasing the working pressure in the range of 10–25 mTorr, followed by thermal annealing at 600°C. The ferroelectric, dielectric, and polarization behaviors of Pb(Mg1/3Ta2/3)0.7Ti0.3O3 films were characterized over a wide range of frequencies. They are strongly affected by the film thickness, where the relative permittivity and remanent polarization increase, while the coercive field decreases with increasing film thickness in the range of 115–360 nm.

Effect of microstructure on the electron-phonon interaction in the disordered metalsPd60Ag40

Using the weak-localization method, we have measured the electron-phonon scattering times ${\ensuremath{\tau}}_{\mathrm{ep}}$ in ${\mathrm{Pd}}_{60}{\mathrm{Ag}}_{40}$ thick films prepared by dc- and rf-sputtering deposition techniques. In both series of samples, we find an anomalous $1/{\ensuremath{\tau}}_{\mathrm{ep}}\ensuremath{\propto}{T}^{2}l$ temperature and disorder dependence, where l is the electron elastic mean free path. This anomalous behavior cannot be explained in terms of the current concepts for the electron-phonon interaction in impure conductors. Our result also reveals that the strength of the electron-phonon coupling is much stronger in the dc- than rf-sputtered films, suggesting that the electron-phonon interaction is not only sensitive to the total level of disorder, but is also sensitive to the microscopic quality of the disorder.

Study of structural changes in amorphous germanium–nitrogen alloys by optical techniques

Thin films of amorphous germanium–nitrogen (a-GeN) alloys prepared by the rf sputtering deposition technique have been studied by Raman scattering spectroscopy. The nitrogen content of the samples varies between zero and ≊3×1022 atoms cm−3, as determined from nuclear reaction analysis data. Modifications of the structural characteristics of the Ge–N alloys, probed through their phonon density, were investigated as a function of the nitrogen concentration. In addition to an increase of the network’s topological disorder, nitrogen is responsible, at relatively high concentrations, for a structural transition in the a-Ge host. The optical and electronic characterization of the samples confirm these changes which are highly dependent on the nitrogen concentration.