Swift heavy ion provoked structural, optical and electrical properties in SnO2 thin films

SnO₂ thin films grown on glass substrates at 300 ^°C by reactive thermal evaporation and annealed at 600 ^°C were irradiated by 120 MeV Ag⁹⁺ ions. Though irradiation is known to induce lattice disorder and suppression of crystallinity, we observe grain growth at a certain fluence of irradiation. X-ray diffraction (XRD) revealed the crystalline nature of the films. The particle size estimated by Scherrer’s formula for the irradiated films was in the range 10–25 nm. The crystallite size increases with increase in fluence up to 1×10¹² ions?cm^?2, whereas after that the size starts decreasing. Atomic force microscope (AFM) results showed the surface modification of nanostructures for films irradiated with fluences of 1×10¹¹ ions?cm^?2 to 1×10¹³ ions?cm^?2. The UV–visible spectrum showed the band gap of the irradiated films in the range of 3.56 eV–3.95 eV. The resistivity decreases with fluence up to 5×10¹² ions?cm^?2 and starts increasing after that. Rutherford Backscattering (RBS) reveals the composition of the films and sputtering of ions due to irradiation at higher fluence.     

Structural,optical and electrical properties of tin oxide thin films by electrostatic spray deposition

Tin oxide (SnO₂) thin films were deposited by electrostatic spray deposition (ESD). The structural, optical and electrical properties of the films for different solvents were studied. The morphology of the deposited thin films was investigated by scanning electron microscopy. The optical transmission spectra of the films showed 66–75% transmittance in the visible region of spectrum. The electrical resistivity of thin films deposited using the different solvents ranged 1.08 × 10^?3–1.34 × 10^?3 Ω-cm. Overall, EG and PG were good solvents for depositing SnO₂ thin films by the ESD technique with stable cone jet.     

Studies of some physical properties of PrFe0.7Ni0.3O3 thin films after 200 MeV Ag15+ irradiation

PrFe_0.7Ni_0.3O₃ thin films (thickness ~ 200 nm) were prepared by pulsed laser ablation technique on LaAlO₃ substrate. These films were irradiated with 200?MeV Ag¹⁵⁺ ions at various fluencies, ranging from 1 × 10¹¹ to 1 × 10¹² ions/cm². These irradiated thin films were characterized by using X-ray diffraction, dc conductivity, dc magnetization and atomic force microscopy. These films exhibit orthorhombic structure and retain it even after irradiations. The crystallite size (110–137?nm), micro strain (1.48 × 10^?2–1.75 × 10^?2 line^?2?m^?4) and dislocation density (79.7 × 10¹⁴–53.2 × 10¹⁴ line/m²) vary with ion fluencies. An enhancement in resistivity at certain fluence and then a decrease in its value (0.22175–0.21813?Ω?cm) are seen. A drastic change in observed magnetism after ion irradiation is seen. With ion irradiation, an increase in surface roughness, due to the formation of hillocks and other factors, is observed. Destruction of magnetic domains after irradiation can also be visualized with magnetic force microscopy and is in close agreement with magnetization data. The impact on various physical properties in these thin films after irradiation indicates a distortion in the lattice structure and consequently on single-particle band width caused by stress-induced defects.     

Silicon negative ion implantation induced vacancy defects in thermally grown SiO2 thin films

ABSTRACT

Thermally grown SiO₂ thin films on a silicon substrate implanted with 100?keV silicon negative ions with fluences varying from 1?×?10¹⁵ to 2?×?10¹⁷ ions cm^?2 have been investigated using Electron spin resonance, Fourier transforms infrared and Photoluminescence techniques. ESR studies revealed the presence of non-bridging oxygen hole centers, E′-centers and P_b-centers at g-values 2.0087, 2.0052 and 2.0010, respectively. These vacancy defects were found to increase with respect to ion fluence. FTIR spectra showed rocking vibration mode, stretching mode, bending vibration mode, and asymmetrical stretching absorption bands at 460, 614, 800 and 1080?cm^?1, respectively. The concentrations of Si–O and Si–Si bonds estimated from the absorption spectra were found to vary between 11.95?×?10²¹ cm^?3 and 5.20?×?10²¹ cm^?3 and between 5.90?×?10²¹ cm^?3 and 3.90?×?10²¹ cm^?3, respectively with an increase in the ion fluence. PL studies revealed the presence of vacancies related to non-bridging oxygen hole centers, which caused the light emission at a wavelength of 720?nm.     

Room-temperature ferromagnetism in N+-implanted ZnO:Mn thin films

Mn–N co-doped ZnO films with wurtzite structure were fabricated by RF magnetron sputtering together with the ion-implantation technique. Then a post-annealing at 650 °C for 10 min in a N₂ atmosphere was performed to activate the implanted N⁺ ions and recover the crystal quality, and a p-type ZnO:Mn–N film with a hole concentration of about 2.1×10¹⁶ cm^?3 was obtained. It is found that the Mn mono-doped ZnO film only exhibits paramagnetic behavior, while after N⁺-implantation, it shows ferromagnetism at 300 K, and the magnetization of the ZnO:Mn–N films can be further enhanced by thermal annealing due to the activation of the N acceptors. Our experimental results confirm that the codoping N acceptors are favorable for ferromagnetic ordering of Mn²⁺ ions in ZnO, which is consistent with the recent theoretical calculations.     

The thermal stability of atomic layer deposited HfLaOx: Material and electrical characterization

HfLaO_x based Metal–oxide–semiconductor capacitors were fabricated by atomic layer deposition in this work. The material and electrical properties of the films along with the high temperature thermal treatment were investigated. It was found that samples undergoing annealing at 900 °C exhibited the best performance. The film was found to be crystallized to a cubic structure at 900 °C, and the roughness of the films was estimated to be 0.332 nm. For electrical characterization, the C–V curve of the film is in good agreement with the corresponding simulated curve, and the capacitor does not show any hysteresis. Moreover, the D_it near the center of silicon band gap exhibits lowest value, and it was calculated to be 2.28 × 10¹¹ eV^?1 cm^?2.     

Effect of Si ion irradiation on polycrystalline CdS thin film grown from novel photochemical deposition technique

CdS thin films have been deposited from aqueous solution by photochemical reactions. The solution contains Cd(CH₃COO)₂ and Na₂S₂O₃, and pH is controlled in an acidic region by adding H₂SO₄. The solution is illuminated with light from a high-pressure mercury-arc lamp. CdS thin films are formed on a glass substrate by the heterogeneous nucleation and the deposited thin films have been subjected to high-energy Si ion irradiations. Si ion irradiation has been performed with an energy of 80 MeV at fluences of 1×10¹¹, 1×10¹², 1×10¹³ and 1×10¹⁴ ions/cm² using tandem pelletron accelerator. The irradiation-induced changes in CdS thin films are studied using XRD, Raman spectroscopy and photoluminescence. Broadening of the PL emission peak were observed with increasing irradiation fluence, which could be attributed to the band tailing effect of the Si ion irradiation. The lattice disorder takes place at high Si ion fluences.     

50 MeV Li3+ ion irradiation effect on structural, electrical, and dielectric properties of PVA-based nanocomposite polymer electrolytes

Nanocomposite polymer electrolyte thin films of polyvinyl alcohol (PVA)-orthophosphoric acid (H₃PO₄)-Al₂O₃ have been prepared by solution cast technique. Films are irradiated with 50 MeV Li³⁺ ions having four different fluences viz. 5?×?10¹⁰, 1?×?10¹¹, 5?×?10¹¹, and 1?×?10¹² ions/cm². The effect of irradiation on polymeric samples has been studied and characterized. X-ray diffraction spectra reveal that percent degree of crystallinity of samples decrease with ion fluences. Glass transition and melting temperatures have been also decreased as observed in differential scanning calorimetry. A possible complexation/interaction has been shown by Fourier transform infrared spectroscopy. Temperature-dependent ionic conductivity shows an Arrhenius behavior before and after glass transition temperature. It is observed that ionic conductivity increases with ion fluences and after a critical fluence, it starts to decrease. Maximum ionic conductivity of ～2.3?×?10^?5 S/cm owing to minimum activation energy of ～0.012 eV has been observed for irradiated electrolyte sample at fluence of 5?×?10¹¹ ions/cm². The dielectric constant and dielectric loss also increase with ion fluences while they decrease with frequency. Transference number of ions shows that the samples are of purely ionic in nature before and after ion irradiation.     

Growth of very large grains in polycrystalline silicon thin films by the sequential combination of vapor induced crystallization using AlCl3 and pulsed rapid thermal annealing

Metal-induced crystallization method is one of the favorable non-laser crystallization methods for thin-film transistors in large-area displays. However, it is necessary to reduce metal contamination in the film to lower leakage current for the device applications. A new two-step crystallization method, consisting of a nucleation step by AlCl₃ vapor-induced crystallization and a grain growth step by a pulsed rapid thermal annealing, has been proposed to increase the grain size and reduce the residual metal contamination in crystallized poly-Si films. The grain size of the poly-Si film crystallized by the VIC + PRTA two-step crystallization process was as large as 70 μm. Furthermore, the Al concentration in the poly-Si film was reduced by two orders of magnitude from 1 × 10²⁰ cm^?3 by VIC only process to 1.4 × 10¹⁸ cm^?3 by the two-step process. As a result, the minimum leakage current of poly-Si TFTs using the poly-Si film prepared by the two-step process was reduced from 1.9 × 10^?10 A/μm to 2.8 × 10^?11 A/μm at a drain voltage of 5 V, without carrier mobility degradation.     

Linear and nonlinear optical properties of rare earth doped of Ba0.7Sr0.3TiO3 thin films

Ba_0.7Sr_0.3TiO₃:Eu ferroelectric films were deposited on quartz substrates by pulsed laser deposition. The linear absorption coefficient and the linear refractive index calculated from the transmission spectrum at 532 nm were found to be 1.67×10⁴ cm^?1 and 1.82 respectively. The room temperature photoluminescence shows the characteristic emission of Eu³⁺ ions. The nonlinear optical properties of the film were investigated by a single beam Z-scan setup. The negative nonlinear refractive index and two photon absorption coefficient was found to be ?1.508×10^?6 m²/GW and 240 m/GW respectively. The real and imaginary part of the third order susceptibility of the thin films is 2.58×10^?17 m²/V² and 1.16×10^?16 m²/V² respectively. The BST:Eu thin films show good optical limiting property.     

Microstructural and optical investigations of Ce-doped barium titanate thin films by FTIR and spectroscopic ellipsometry

(BaTiO₃)_{1? x} (CeO₂) _x (with x?=?0,?1,?3,?5.7 and 16 at.%) thin films were prepared by electron beam evaporation method. According to X-ray diffraction, nanosized and amorphous Ce-doped barium titanate thin films were obtained. The crystallinity diminished as Ce content increased. The increase in the Ce slightly shifts the absorption peaks at 433–450 and 416–424?cm^?1 to higher wavenumbers. A two-layer model was used to describe the experimental ellipsometric data. The Bruggeman effective medium approximation (BEMA) was used to describe the surface roughness layer and the Cauchy dispersion relation was used to describe the main Ce-doped barium titanate layer. The refractive index and the extinction coefficient were found to increase with increasing Ce content; however, the optical band gap decreased with increasing Ce content. The accurate determination of the optical constants of Ce-doped barium titanate thin films may favor them in the applications of optical thin film devices.     

Synthesis of Ag metallic nanoparticles by 120 keV Ag− ion implantation in TiO2 matrix

TiO₂ thin film synthesized by the RF sputtering method has been implanted by 120 keV Ag^? ion with different doses (3?×?10¹⁴, 1?×?10¹⁵, 3?×?10¹⁵, 1?×?10¹⁶ and 3?×?10¹⁶ ions/cm²). Further, these were characterized by Rutherford back Scattering, XRD, X-ray photoelectron spectroscopy (XPS), UV–visible and fluorescence spectroscopy. Here we reported that after implantation, localized surface Plasmon resonance has been observed for the fluence 3?×?10¹⁶ ions/cm², which was due to the formation of silver nanoparticles. Ag is in metallic form in the matrix of TiO₂, which is very interestingly as oxidation of Ag was reported after implantation. Also, we have observed the interaction between nanoparticles of Ag and TiO₂, which results in an increasing intensity in lower charge states (Ti³⁺) of Ti. This interaction is supported by XPS and fluorescence spectroscopy, which can help improve photo catalysis and antibacterial properties.     

ArF excimer laser deposition of wide-band gap solid electrolytes for thin film batteries

High quality solid electrolyte thin films was grown by pulsed laser deposition (PLD) using a high photon energy ArF excimer laser. Various amorphous thin films were successfully deposited on glass substrates from oxide targets; such as Li₃PO₄, LiBO₂, Li₂SiO₃, Li₂CO₃, Li₂SO₄, Li₂ZrO₃, LiAlO₂, Li₂WO₄ and Ohara glass ceramics. The morphology, optical property and ionic conductivity of these films were examined by optical microscope, UV–VIS spectroscopy and impedance analysis. Dramatic improvement of the film morphology was observed by using a high photon energy laser, while the broken film with many droplets was obtained by using lower ones. Ionic conductivity of the films was examined by impedance spectroscopy and dc polarization method. For example, an ionic conductivity of a Li₃PO₄ film was 4.6 × 10^? 6 S cm^? 1 at 25 °C with activation energy of 0.57 eV. Electronic conductivity measurements revealed that most of the films were pure lithium ion conductors, while a Li₂WO₄ film was a mixed conductor.     

The near surface changes in boron implanted 4145 steel

Boron implanted 4145 steel was evaluated for changes in the near-surface region property such as microhardness. The surfaces when implanted with ¹¹B⁺ ions at 135 keV energy to a dose 1 × 10¹⁷ ions cm^?2 resulted in increase of microhardness for 10 to 40 gms of applied load. An increase upto 40% in microhardness could be observed in the specimen when annealed at 310δC for 3 hours. Furthermore, the effect of ion-beam induced intermixing of 250Å thin carbon film due to boron implantation was also studied for different doses ranging from 1 × 10¹⁷ to 3 × 10¹⁷ boron ions cm^?2. An increase in microhardness with applied load was observed for 1 × 10¹⁷ ions cm^?2 concentration, while hardest layer was formed at 3 × 10¹⁷ ions cm^?2 dose which practically had very little effect to 10 and 20 gms of load.     

Ion beam synthesis and investigation of nanocomposite multiferroics based on barium titanate with 3d metal nanoparticles

Samples of nanocomposite multiferroics have been synthesized by implantation of Co⁺, Fe⁺, and Ni⁺ ions with an energy of 40 keV into ferroelectric barium titanate plates to doses in the range (0.5–1.5) × 10¹⁷ ions/cm². It has been found that nanoparticles of metallic iron, cobalt, or nickel are formed in the barium titanate layer subjected to ion bombardment. With an increase in the implantation dose, the implanted samples sequentially exhibit superparamagnetic, soft magnetic, and, finally, strong ferromagnetic properties at room temperature. The average sizes of ion-synthesized 3d-metal nanoparticles vary in the range from 5 to 10 nm depending on the implantation dose. Investigation of the orientation dependence of the magnetic hysteresis loops has demonstrated that the samples show a uniaxial (“easy plane”) magnetic anisotropy typical of thin granular magnetic films. Ferromagnetic BaTiO₃: 3d metal samples are characterized by a significant shift of the ferromagnetic resonance signal in an external electric field, as well as by a large (in magnitude) magnetodielectric effect at room temperature. These results indicate that there is a strong magnetoelectric coupling between the ferroelectric barium titanate matrix and ion-synthesized nanoparticles of magnetic metals.     

(111)取向(Pb,La)TiO3铁电薄膜中90°纳米带状畴与热释电性能的研究

采用射频磁控溅射技术在Pt/Ti/SiO₂/Si(100)衬底上生长了掺镧钛酸铅(PLT)铁电薄膜.用X射线衍射技术(XRD)研究了PLT薄膜结晶性能，结果表明PLT薄膜为 (111)择优取向钙钛矿相织构.使用原子力显微镜(AFM)和压电响应力显微镜(PFM) 分别观察了PLT薄膜的表面形貌和对应区域的电畴结构.PFM观察显示PLT薄膜中存在90°纳米带状畴，电畴的极化为首尾相接的低能量的排列方式，带状畴的宽度为20—60nm.研究了PLT10铁电薄膜的制备条件与性能之间的关系.发现在优化条件下制备的PLT10铁电薄膜的介电常数ε_r为365、介电损耗tgδ为0.02，热释电系数γ为2.18×10^-8C·(cm²·K)^-1，可以满足制备非制冷红外探测器的需要. 关键词： PLT薄膜 电畴 PFM 极化     

Thin TiO2 grown by metal–organic chemical vapor deposition on (NH4)2S x -treated InP

The electrical characteristics of thin TiO₂ films prepared by metal–organic chemical vapor deposition grown on a p-type InP substrate were studied. For a TiO₂ film of 4.7 nm on InP without and with ammonium sulfide treatment, the leakage currents are 8.8×10⁻² and 1.1×10⁻⁴ A/cm² at +2 V bias and 1.6×10⁻¹ and 8.3×10⁻⁴ A/cm² at −2 V bias. The lower leakage currents of TiO₂ with ammonium sulfide treatment arise from the improvement of interface quality. The dielectric constant and effective oxide charge number density are 33 and 2.5×10¹³ cm², respectively. The lowest mid-gap interface state density is around 7.6×10¹¹ cm⁻² eV⁻¹. The equivalent oxide thickness is 0.52 nm. The breakdown electric field increases with decreasing thickness in the range of 2.5 to 7.6 nm and reaches 9.3 MV/cm at 2.5 nm.     

Thermo,Iono and photoluminescence properties of 100 MeV Si7+ ions bombarded CaSiO3:Eu3+ nanophosphor

This paper reports on the thermo (TL), iono (IL) and photoluminescence (PL) properties of nanocrystalline CaSiO₃:Eu³⁺ (1–5 mol %) bombarded with 100 MeV Si⁷⁺ ions for the first time. The effect of different dopant concentrations and influence of ion fluence has been discussed. The characteristic emission peaks ⁵D₀→⁷F_J (J=0, 1, 2, 3, 4) of Eu³⁺ ions was recorded in both PL (1×10¹¹–1×10¹³ ions cm^?2) and IL (4.16×10¹²–6.77×10¹² ions cm^?2) spectra. It is observed that PL intensity increases with ion fluence, whereas in IL the peaks intensity increases up to fluence 5.20×10¹² ions cm^?2, then it decreases. A well resolved TL glow peak at ～304 °C was recorded in all the ion bombarded samples at a warming rate of 5 °C s^?1. The TL intensity is found to be maximum at 5 mol% Eu³⁺ concentration. Further, TL intensity increases sub linearly with shifting of glow peak towards lower temperature with ion fluence.     

Effect of Ge doping on the electrical properties of amorphous Zn–Sn–O thin films

We report the effect of germanium doping on the active layer of amorphous Zinc–Tin-Oxide (a-ZTO) thin film transistor (TFT). Amorphous thin film samples were prepared by RF magnetron sputtering using single targets composed of Zn₂Ge_0.05Sn_0.95O₄ and Zn₂SnO₄ with variable oxygen contents in the sputtering gases. In comparison with undoped, Ge-doped a-ZTO films exhibited five order of magnitude lower carrier density with a significantly higher Hall-mobility, which might be due to suppressed oxygen vacancies in the a-ZTO lattice since the Ge substituent for the Sn site has relatively higher oxygen affinity. Thus, the bulk and interface trap densities of Ge-doped a-ZTO film were decreased one order of magnitude to 7.047 × 10¹⁸ eV⁻¹cm⁻³ and 3.52 × 10¹¹ eV⁻¹cm⁻², respectively. A bottom-gate TFT with the Ge-doped a-ZTO active layer showed considerably improved performance with a reduced SS, positively shifted V_th, and two orders of magnitude increased I_on/I_off ratio, attributable to the doped Ge ions.     

Influence of 120 MeV Si9+ ion irradiation on ZnTe semiconductor thin films

ABSTRACT

ZnTe (Zinc Telluride) is a potential semiconducting material for many optoelectronic devices like solar cells and back contact material for CdTe-based solar cells. In the present study, ZnTe thin films were prepared by thermal evaporation technique and then irradiated with 120?MeV Si⁹⁺ ions at different fluences. These films are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–Visible spectroscopy techniques. XRD study confirms increased crystallinity and grain growth for post-irradiated ZnTe thin films for fluences, up to 1?×?10¹¹ ions cm^?2. However, the grain size and crystallinity decreased for higher fluence-exposed samples. SEM images confirm the observed structural properties. Modification of the surface morphology of the film due to the ion irradiation with different fluences is studied. Optical band gap of film is decreased from 2.31?eV (pristine) to 2.17?eV after irradiation of Si⁹⁺ ions.