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1.
Titanium oxide thin films were deposited on p-type Si(100), SiO2/Si, and Pt/Si substrates by plasma enhanced chemical vapor deposition using high purity Ti(O-i-C3H7)4 and oxygen. As-deposited amorphous TiO2 thin films were treated by rapid thermal annealing (RTA) in oxygen ambient, and the effects of RTA conditions on the structural
and electrical properties of TiO2 films were studied in terms of crystallinity, microstructure, current leakage, and dielectric constant. The dominant crystalline
structures after 600 and 800 ‡C annealing were an anatase phase for the TiO2 film on SiO2/Si and a rutile phase for the film on a Pt/Si substrate. The dielectric constant of the as-grown and annealed TiO2 thin films increased depending on the substrate in the order of Si, SiO2/Si, and Pt/ Si. The SiO2 thin layer was effective in preventing the formation of titanium silicide at the interface and current leakage of the film.
TEM photographs showed an additional growth of SiOx from oxygen supplied from both SiO2 and TiO2 films when the films were annealed at 1000 ‡C in an oxygen ambient. Intensity analysis of Raman peaks also indicated that
optimizing the oxygen concentration and the annealing time is critical for growing a TiO2 film having high dielectric and low current leakage characteristics. 相似文献
2.
Amorphous LiCoO2 thin films were deposited on the NASICON-type glass ceramics, Li1+x+yAlxTi2−xSiyP3−yO12 (LATSP), by radio frequency (RF) magnetron sputtering below 180 °C. The as-deposited LiCoO2 thin films were characterized by X-ray diffraction, scanning electron microscopy and atomic force microscope. All-solid-state Li/PEO18-Li (CF3SO2)2N/LATSP/LiCoO2/Au cells were fabricated using the amorphous film. The electrochemical performance of the cells was investigated by galvanostatic cycling, cyclic voltammetry, potentiostatic intermittent titration technique and electrochemical impedance spectroscopy. It was found that the amorphous LiCoO2 thin film shows a promising electrochemical performance, making it a potential application in microbatteries for microelectronic devices. 相似文献
3.
SiC formation for a solar cell passivation layer using an RF magnetron co-sputtering system 总被引:1,自引:0,他引:1
In this paper, we describe a method of amorphous silicon carbide film formation for a solar cell passivation layer. The film
was deposited on p-type silicon (100) and glass substrates by an RF magnetron co-sputtering system using a Si target and a
C target at a room-temperature condition. Several different SiC [Si1-xCx] film compositions were achieved by controlling the Si target power with a fixed C target power at 150 W. Then, structural,
optical, and electrical properties of the Si1-xCx films were studied. The structural properties were investigated by transmission electron microscopy and secondary ion mass
spectrometry. The optical properties were achieved by UV-visible spectroscopy and ellipsometry. The performance of Si1-xCx passivation was explored by carrier lifetime measurement. 相似文献
4.
Hong-Hsin HuangMoo-Chin Wang Huey-Jiuan LinMin-Hsiung Hon Fu-Yuan HsiaoNan-Chung Wu Chi-Shiung Hsi 《Ceramics International》2011,37(8):3167-3172
Four-layer SrTiO3/BaTiO3 thin films ((ST/BT)4) with various thicknesses deposited on Pt/Ti/SiO2/Si substrates at 500 °C by double target RF magnetron sputtering have been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), profilometry, capacitance-voltage and current-voltage measurements. The XRD patterns reveal the frame formation of the sputter deposited (ST/BT)4 with controlled modulation. The adhesion between the Pt bottom electrode layer and the BT layer is excellent. The dielectric constant of the (ST/BT)4 multilayer thin film increases with increasing film thickness. The effects of temperature, frequency, and bias voltage on the dielectric constant of the (ST/BT)4 multilayer thin films are discussed in detail. The leakage current density of the (ST/BT)4 multilayer with a thickness of 450.0 nm is lower than 1.0 × 10−8 A/cm2 for the applied voltage of less than 5 V, showing that the multilayer thin films with such a characteristic could be applied for use in dynamic random access memory (DRAMs) capacitors. 相似文献
5.
Pure polycrystalline Bi1−xSmxFeO3 (BSFO) (x=0–0.12) thin films were successfully prepared on FTO/glass substrates by the sol–gel method. The influence of Sm doping on the structure, dielectric, leakage current, ferroelectric and ferromagnetic properties of the BSFO films was investigated. X-ray diffraction analysis and FE-SEM images both reveal a gradual rhombohedra to pseudo-tetragonal phase transition with the increase of Sm dopant content. On one hand, a proper amount of Sm doping can decrease the leakage current densities of the BSFO thin films. On the other hand, excess Sm substitution for Bi will lead to multiphase coexistence in the film, the lattice inhomogeneity results in more defects in the film, which can increase the leakage current density. The result shows that defects in the complexes lead to electric domain back-switching in the BSFOx=0.06 thin film, resulting in a decreased dielectric constant, leakage current and remanent polarization. The BSFOx=0.09 thin film is promising in practical application because of its highest dielectric constant, remanent polarization and remanent magnetization of 203–185, 70 μC/cm2 and 1.31 emu/cm3, respectively. 相似文献
6.
Dense and crack-free aluminum oxide films were fabricated by sol–gel spin-coating technology. Aluminum nitrate (Al(NO3)3.9H2O) was used as the precursor material. X-ray diffraction shows that the fabricated films are amorphous. X-ray photoelectron spectroscopy confirms that the thin films are alumina (Al2O3). Field-emission scanning electron microscopy images of the films reveal that the films are compact with a dense cross section. Dielectric measurements were carried out on samples with a metal–insulator–metal structure. The electrical characteristics of the films were affected by the thermal sintering temperature of the films. The leakage current density of the films decreases with the increase in the sintering temperature and increases with the increase in the measuring temperature. The leakage current shows a linear dependence on the voltage in the low-electric field-regime. The current density ascends to higher values due to the effect of space charges in the high-electric-field regime. The ionization energy of the top-electrode metals (Au, Pt or Ti–Au) has a strong effect on the leakage current. 相似文献
7.
The effect of heating temperatures on the electrical properties of sol–gel-derived (Zr,Sn)TiO4 thin films deposited on a p-type (1 0 0) Si substrate was studied. The leakage currents of films with two different heating temperatures chosen to burn-out the solvent as a function of applied voltage were measured at different temperatures. The activation energies obtained from the Arrhenius plot of the leakage current density versus measured temperature for (Zr,Sn)TiO4 films were then extracted. Additionally, microstructures of films with two different heating temperatures chosen to burn-out the solvent were analyzed by a conductive atomic force microscope (AFM) and an X-ray diffraction (XRD). Finally, the conductive mechanisms of leakage current and leakage current correlated to microstructures were also discussed. 相似文献
8.
Debanjan Jana Siddheswar Maikap Amit Prakash Yi-Yan Chen Hsien-Chin Chiu Jer-Ren Yang 《Nanoscale research letters》2014,9(1):12
Enhanced resistive switching phenomena of IrOx/GdOx/W cross-point memory devices have been observed as compared to the via-hole devices. The as-deposited Gd2O3 films with a thickness of approximately 15 nm show polycrystalline that is observed using high-resolution transmission electron microscope. Via-hole memory device shows bipolar resistive switching phenomena with a large formation voltage of -6.4 V and high operation current of >1 mA, while the cross-point memory device shows also bipolar resistive switching with low-voltage format of +2 V and self-compliance operation current of <300 μA. Switching mechanism is based on the formation and rupture of conducting filament at the IrOx/GdOx interface, owing to oxygen ion migration. The oxygen-rich GdOx layer formation at the IrOx/GdOx interface will also help control the resistive switching characteristics. This cross-point memory device has also Repeatable 100 DC switching cycles, narrow distribution of LRS/HRS, excellent pulse endurance of >10,000 in every cycle, and good data retention of >104 s. This memory device has great potential for future nanoscale high-density non-volatile memory applications. 相似文献
9.
Hui Xia 《Electrochimica acta》2007,52(24):7014-7021
LiCoO2 thin films were prepared by pulsed laser deposition (PLD) on Pt/Ti/SiO2/Si (Pt) and Au/MgO/Si (Au) substrates, respectively. Crystal structures and surface morphologies of thin films were investigated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The LiCoO2 thin films deposited on the Pt substrates exhibited a preferred (0 0 3) texture with smooth surfaces while the LiCoO2 thin films deposited on the Au substrates exhibited a preferred (1 0 4) texture with rough surfaces. The electrochemical properties of the LiCoO2 films with different textures were compared with charge-discharge, dQ/dV, and Li diffusion measurements (PITT). Compared with the (1 0 4)-textured LiCoO2 thin films, the (0 0 3)-textured thin films exhibited relatively lower electrochemical activity. However, the advantage of the (1 0 4)-textured film only remained for a small number of cycles due to the relatively faster capacity fade. Li diffusion measurements showed that the Li diffusivity in the (0 0 3)-textured film is one order of magnitude lower than that in the (1 0 4)-textured film. As discussed in this paper, we believe that Li diffusion through grain boundaries is comparable to or even faster than Li diffusion through the grains. 相似文献
10.
Wei Li Ping Liu Yongsheng Zhao Fengcang Ma Xinkuan Liu Xiaohong Chen Daihua He 《Nanoscale research letters》2013,8(1):427
In order to clarify the controversies of hardening mechanism for TiN/SiNx-based nanocomposite films, the microstructure and hardness for TiN/SiNx and TiAlN/SiNx nanocomposite films with different Si content were studied. With the increase of Si content, the crystallization degree for two series of films firstly increases and then decreases. The microstructural observations suggest that when SiNx interfacial phase reaches to a proper thickness, it can be crystallized between adjacent TiN or TiAlN nanocrystallites, which can coordinate misorientations between nanocrystallites and grow coherently with them, resulting in blocking of the dislocation motions and hardening of the film. The microstructure of TiN/SiNx-based nanocomposite film can be characterized as the nanocomposite structure with TiN-based nanocrystallites surrounded by crystallized SiNx interfacial phase, which can be denoted by nc-TiN/c-SiNx model (''c’ before SiNx means crystallized) and well explain the coexistence between nanocomposite structure and columnar growth structure within the TiN/SiNx-based film. 相似文献
11.
Resistive switching memory characteristics of Ge/GeOx nanowires and evidence of oxygen ion migration
Amit Prakash Siddheswar Maikap Sheikh Ziaur Rahaman Sandip Majumdar Santanu Manna Samit K Ray 《Nanoscale research letters》2013,8(1):220
The resistive switching memory of Ge nanowires (NWs) in an IrOx/Al2O3/Ge NWs/SiO2/p-Si structure is investigated. Ge NWs with an average diameter of approximately 100 nm are grown by the vapor–liquid-solid technique. The core-shell structure of the Ge/GeOx NWs is confirmed by both scanning electron microscopy and high-resolution transmission electron microscopy. Defects in the Ge/GeOx NWs are observed by X-ray photoelectron spectroscopy. Broad photoluminescence spectra from 10 to 300 K are observed because of defects in the Ge/GeOx NWs, which are also useful for nanoscale resistive switching memory. The resistive switching mechanism in an IrOx/GeOx/W structure involves migration of oxygen ions under external bias, which is also confirmed by real-time observation of the surface of the device. The porous IrOx top electrode readily allows the evolved O2 gas to escape from the device. The annealed device has a low operating voltage (<4 V), low RESET current (approximately 22 μA), large resistance ratio (>103), long pulse read endurance of >105 cycles, and good data retention of >104 s. Its performance is better than that of the as-deposited device because the GeOx film in the annealed device contains more oxygen vacancies. Under SET operation, Ge/GeOx nanofilaments (or NWs) form in the GeOx film. The diameter of the conducting nanofilament is approximately 40 nm, which is calculated using a new method. 相似文献
12.
《Ceramics International》2016,42(10):11640-11649
The microstructure, optical and electrical properties of HfTiO high-k gate dielectric thin films deposited on Si substrate and quartz substrate by RF magnetron sputtering have been investigated. Based on analysis from x-ray diffraction (XRD) measurements, it has been found that the as-deposited HfTiO films remain amorphous regardless of the working gas pressure. Meanwhile, combined with characterization of ultraviolet-visible spectroscopy (UV–vis) and spectroscopy ellipsometry (SE), the deposition rate, band gap and optical properties of sputtered HfTiO gate dielectrics were determined. Besides, by means of the characteristic curves of high frequency capacitance–voltage (C–V) and leakage current density–voltage (J–V), the electrical parameters, such as permittivity, total positive charge density, border trap charge density, and leakage current density, have been obtained. The leakage current mechanisms are also discussed. The energy band gap of 3.70 eV, leakage current density of 1.39×10−5 A/cm2 at bias voltage of 2 V, and total positive charge density and border trap charge density of 9.16×1011 cm−2 and 1.3×1011 cm−2, respectively render HfTiO thin films deposited at 0.6 Pa, potential high-k gate dielectrics in future CMOS devices. 相似文献
13.
Si heterojunction solar cells were fabricated on p-type single-crystal Si (sc-Si) substrates using phosphorus-doped Si nanocrystals (Si-NCs) embedded in SiNx (Si-NCs/SiNx) films as emitters. The Si-NCs were formed by post-annealing of silicon-rich silicon nitride films deposited by electron cyclotron resonance chemical vapor deposition. We investigate the influence of the N/Si ratio in the Si-NCs/SiNx films on their electrical and optical properties, as well as the photovoltaic properties of the fabricated heterojunction devices. Increasing the nitrogen content enhances the optical gap E04 while deteriorating the electrical conductivity of the Si-NCs/SiNx film, leading to an increased short-circuit current density and a decreased fill factor of the heterojunction device. These trends could be interpreted by a bi-phase model which describes the Si-NCs/SiNx film as a mixture of a high-transparency SiNx phase and a low-resistivity Si-NC phase. A preliminary efficiency of 8.6% is achieved for the Si-NCs/sc-Si heterojunction solar cell. 相似文献
14.
C60 fullerene clusters are used as a carbon source for amorphous carbon films deposition in an electron beam excited plasma. C60 clusters are sublimated by heating a ceramic crucible containing the C60 powders up to 850 °C, which is located in a highly vacuumed process chamber. The sublimated fullerene powders are injected to the electron beam excited argon plasma and dissociated to be active species that are propelled toward the substrates. Consequently, the carbon species condense as a thin film onto the negatively biased substrates that are immersed in the plasma. Deposition rates of approximately 1.0 μm/h and the average surface roughness of 0.2 nm over an area of 400 μm2 are achieved. Decomposition of the C60 fullerene after injecting into the plasma is confirmed by optical emission spectroscopy that shows existence of small carbon species such as C2 in the plasma. X-ray diffraction pattern reveals that the microstructure of the film is amorphous, while fullerene films deposited without the plasma show crystalline structure. Raman spectroscopic analysis shows that the films deposited in the plasma are one of the types of diamond-like carbon films. Different negative bias voltages have been applied to the substrate holder to examine the effect of the bias voltage to the properties of the films. The nano-indentation technique is used for hardness measurement of the films and results in hardness up to about 28 GPa. In addition, the films are droplet-free and show superior lubricity. 相似文献
15.
《Ceramics International》2017,43(3):3101-3106
Deposition of HfAlOx gate dielectric films on n-type Si and quartz substrates by sol-gel technique has been performed and the optical, electrical characteristics of the as-deposited HfAlOx thin films as a function of annealing temperature have been investigated. The optical properties of HfAlOx thin films related to annealing temperature are investigated by ultraviolet-visible spectroscopy (UV–vis) and spectroscopy ellipsometry (SE). By measurement of UV–vis, average transmission of all the HfAlOx samples are about 85% owing to their uniform composition. And the increase in band gap has been observed with the increase of annealing temperature. Moreover, the increase of refractive index (n) and density with the increase of annealing temperature are obtained by SE measurements. Additionally, the electrical properties based on Al/Si/HfAlOx/Al capacitor are analyzed by means of the high frequency capacitance-voltage (C-V) and the leakage current density-voltage (J-V) characteristics. Results have shown that 400 °C-annealed sample demonstrates good electrical performance, including larger dielectric constant of 12.93 and lower leakage current density of 3.75×10−7 A/cm2 at the gate voltage of 1 V. Additionally, the leakage current conduction mechanisms as functions of annealing temperatures are also discussed systematically. 相似文献
16.
Investigation of Tb-doping on structural transition and multiferroic properties of BiFeO3 thin films
Pure BiFeO3 (BFO) and Bi1−xTbxFeO3 (BTFO) thin films were successfully prepared on FTO (fluorine doped tin oxide) substrates by the sol–gel spin-coating method. The effects of Tb-doping on the structural transition, leakage current, and dielectric and multiferroic properties of the BTFO thin films have been investigated systematically. XRD, Rietveld refinement and Raman spectroscopy results clearly reveal that a structural transition occurs from the rhombohedral (R3c:H) to the biphasic structure (R3c:H+R-3m:R) with Tb-doping. The leakage current density of BTFOx=0.10 thin film is two orders lower than that of the pure BFO, i.e. 5.1×10−7 A/cm2 at 100 kV/cm. Furthermore, the electrical conduction mechanism of the BTFO thin films is dominated by space-charge-limited conduction. The two-phase coexistence of BTFOx=0.10 gives rise to the superior ferroelectric (2Pr=135.1 μC/cm2) and the enhanced ferromagnetic properties (Ms=6.3 emu/cm3). The optimal performance of the BTFO thin films is mainly attributed to the biphasic structure and the distorted deformation of FeO6 octahedra. 相似文献
17.
Spin-coating was performed to fabricate amorphous high-entropy oxide (HEO) (AlTiVZrHf)Ox films on Si substrates. The films were evaluated through X-ray photoelectron spectroscopy and through transmission electron microscopy (TEM)-based energy-dispersive spectroscopy (EDS) mapping, which respectively revealed all constituent elements and the homogenous distributions and no aggregation of those elements. TEM analysis revealed four distinct layers—a crystalline Al metal gate, an amorphous Al2O3 interfacial layer, amorphous (AlTiVZrHf)Ox, and native amorphous SiO2—in a patterned metal–oxide–semiconductor (MOS) gate stack on the Si substrate. The resulting stack exhibited a low leakage current density (JL) and no frequency dispersion in its capacitance–voltage characteristics after undergoing forming gas annealing. The obtained dielectric constant (k ≈ 32) for the HEO film is promising for advanced gate stacks and transistor applications. Although the film exhibited minor nanocrystallinity and the stack exhibited no interfacial Al2O3 layer after rapid thermal annealing at 900 °C, a low JL, distinct layers, and a clearly defined interface between the (AlTiVZrHf)Ox and SiO2 were observed, indicating no substantial diffusion among these layers. EDS mapping revealed the homogenous distribution of each constituent element without aggregation. Medium-entropy-oxide films and their MOS devices were fabricated for comparison; however, they exhibited inferior performance. 相似文献
18.
Comparison of resistive switching memory characteristics using copper (Cu) and aluminum (Al) electrodes on GeOx/W cross-points has been reported under low current compliances (CCs) of 1 nA to 50 μA. The cross-point memory devices are observed by high-resolution transmission electron microscopy (HRTEM). Improved memory characteristics are observed for the Cu/GeOx/W structures as compared to the Al/GeOx/W cross-points owing to AlOx formation at the Al/GeOx interface. The RESET current increases with the increase of the CCs varying from 1 nA to 50 μA for the Cu electrode devices, while the RESET current is high (>1 mA) and independent of CCs varying from 1 nA to 500 μA for the Al electrode devices. An extra formation voltage is needed for the Al/GeOx/W devices, while a low operation voltage of ±2 V is needed for the Cu/GeOx/W cross-point devices. Repeatable bipolar resistive switching characteristics of the Cu/GeOx/W cross-point memory devices are observed with CC varying from 1 nA to 50 μA, and unipolar resistive switching is observed with CC >100 μA. High resistance ratios of 102 to 104 for the bipolar mode (CCs of 1 nA to 50 μA) and approximately 108 for the unipolar mode are obtained for the Cu/GeOx/W cross-points. In addition, repeatable switching cycles and data retention of 103 s are observed under a low current of 1 nA for future low-power, high-density, nonvolatile, nanoscale memory applications. 相似文献
19.
Iulia Salaoru Qingjiang Li Ali Khiat Themistoklis Prodromakis 《Nanoscale research letters》2014,9(1):552
This work exploits the coexistence of both resistance and capacitance memory effects in TiO2-based two-terminal cells. Our Pt/TiO2/TiO
x
/Pt devices exhibit an interesting combination of hysteresis and non-zero crossing in their current-voltage (I-V) characteristic that indicates the presence of capacitive states. Our experimental results demonstrate that both resistance and capacitance states can be simultaneously set via either voltage cycling and/or voltage pulses. We argue that these state modulations occur due to bias-induced reduction of the TiO
x
active layer via the displacement of ionic species. 相似文献
20.
The Na0.5Bi0.5TiO3 (NBT) thin films sandwiched between Au electrodes and fluorine-doped tin oxide (FTO) conducting glass were deposited using a sol–gel method. Based on electrochemical workstation measurements, reproducible resistance switching characteristics and negative differential resistances were obtained at room temperature. A local impedance spectroscopy measurement of Au/NBT was performed to reveal the interface-related electrical characteristics. The DC-bias-dependent impedance spectra suggested the occurrence of charge and mass transfer at the interface of the Au/NBT/FTO device. It was proposed that the first and the second ionization of oxygen vacancies are responsible for the conduction in the low- and high-resistance states, respectively. The experimental results showed high potential for nonvolatile memory applications in NBT thin films. 相似文献