共查询到20条相似文献,搜索用时 31 毫秒
1.
Soojin Wi N. Senthilkumar Shi-Woo Rhee 《Journal of Materials Science: Materials in Electronics》2008,19(1):45-50
Thin films of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) 50/50 copolymer were prepared by spin coating on p-Si
substrate. Thermal behavior of the film was observed by measuring the film thickness with ellipsometry as a function of the
temperature and abrupt volume expansion was observed at 130–150 °C. Capacitance-voltage (C-V) and current-voltage (I-V) behavior
of the aluminum/P(VDF-TrFE)/p-Si MIS (metal-insulator-semiconductor) structures were studied and dielectric constant of the
P(VDF-TrFE) film was measured to be about 15.3 at optimum condition. No hysteresis was observed in the C-V curve for films
as deposited and annealed (70–200 °C). Films annealed at temperatures higher than the volume expansion temperature showed
substantial surface roughness due to the crystallization. Flat band voltage (VFB) of the MIS structure with as deposited films was about −0.3 V and increased up to −2.0 V with annealing. This suggested
that positive charges were generated in the film. Electronic properties of the annealed P(VDF-TrFE) film at above melting
temperature were degraded substantially with larger shift in flat band voltage, low dielectric constant and low breakdown
voltage. Organic thin film transistor with pentacene active layer and P(VDF-TrFE) as a gate dielectric layer showed a mobility
of 0.31 cm2/V·s and threshold voltage of −0.45 V. 相似文献
2.
SrBi4Ti4O15 (SBTi) and Bi-excess and Sr-deficient SBTi (Sr-deficient SBTi, Sr0.8Bi4.13Ti4O15) thin films were deposited on Pt/Ti/SiO2/Si (100) substrates using a sol–gel method. Structure and electric properties were investigated systematically. These films
were random oriented. The remnant polarization (2P
r) of SBTi film was about 25.3 μC/cm2, which was larger than the reported value of SBTi thin film. The film with Sr-deficient and Bi-excess composition showed
a very large remnant polarization of 36.6 μC/cm2. The capacitance–voltage (C–V) characteristics of both the films showed normal ferroelectric behavior. The Curie temperatures of the same Sr-deficient
and Bi-excess component ceramics sample increased slightly in comparison with that of SBTi. More importantly, the Sr-deficient
and Bi-excess SBTi thin film showed high fatigue resistance against continuous switching up to 4.4 × 1010 cycles. 相似文献
3.
Fabrication and comparative study of top-gate and bottom-gate ZnO–TFTs with various insulator layers
XinAn Zhang JingWen Zhang WeiFeng Zhang Xun Hou 《Journal of Materials Science: Materials in Electronics》2010,21(7):671-675
Transparent ZnO thin film transistors (ZnO–TFTs) with different structures and dielectric layers were fabricated by rf magnetron
sputtering. The PbTiO3, AlO
x
, SiN
x
and SiO
x
films were attempted to serve as the gate dielectric layers in the devices, respectively, and XRD was employed to investigate
the crystal structure of ZnO films deposited on these dielectric layers. The optical properties of transparent TFTs were measured
and revealed the average transmittance ranged from 60 to 80% in the visible part of the spectrum. Electrical measurement shows
the properties of the ZnO–TFTs have great relations with the device structure. The bottom-gate TFTs have better behaviors
than top-gate ones with the mobility, threshold voltage and the current on/off ratio of 18.4 cm2 V−1 s−1, −0.7 V and 104, respectively. The electrical difference of the devices may be due to different character of the interface between the channel
and dielectric layers. 相似文献
4.
Y. Kumashiro K. Nakamura T. Enomoto M. Tanaka 《Journal of Materials Science: Materials in Electronics》2011,22(8):966-973
The chemical vapor deposited (CVD) BP films on Si(100) (190 nm)/SiO
x
(370 nm)/Si(100) (625 μm) (SOI) and sapphire (R-plane) (600 μm) substrates were prepared by the thermal decomposition of
the B2H6–PH3–H2 system in the temperature range of 800–1050 °C for the deposition time of 1.5 h. The BP films were epitaxially grown on the
SOI substrate, but a two-step growth method, i.e., a buffer layer at lower temperature and sequent CVD process at 1000 °C
for 1.5 h was effective for obtaining a smooth film on the sapphire substrate. The electrical conduction types and electrical
properties of these films depended on the growth temperature, gases flow rates and substrates. The thermal conductivity of
the film could be replaced by the substrate, so that the calculated thermoelectric figure-of-merit (Z) for the BP films on the SOI substrate was 10−4–10−3/K at 700–1000 K. Those on the sapphire substrate were 10−6–10−5/K for the direct growth and 10−5–10−4/K for the two-step growth at 700–900 K, indicating that the film on a sapphire by two-step growth would reduce the defect
concentrations and promote the electrical conductivity. 相似文献
5.
Li Jia Yu Jun Wang Yunbo Peng Gang Li Jianjun 《Journal of Materials Science: Materials in Electronics》2010,21(2):137-140
Bi3.15Nd0.85Ti3O12 (BNT) thin film with a thin LaNiO3 film as buffer layer was fabricated by sol–gel method on Pt/TiO2/SiO2/Si substrate. The BNT thin films have a perovskite phase with a dense microstructure. The P
r and V
c value are 25.5 μc/cm2 and 3.7 V, respectively under the applied voltage of 15 V. After the switching of 2 × 109 cycles, the P
r value decreases to 86% of its pre-fatigue value. The leakage current density of the BNT thin films with LaNiO3 buffer layer were generally in the order of 10−8 to 10−6 A/cm2. The fatigue and leakage current properties were improved dramatically compared with the BNT film without a LaNiO3 buffer layer that we prepared before. The measured residual stress was tensile stress and its value was 176 MPa. 相似文献
6.
Ö. Güllü M. Biber A. Türüt 《Journal of Materials Science: Materials in Electronics》2008,19(10):986-991
In this study, we identically prepared the aniline green/p-Si organic–inorganic devices (total 27 diodes) formed by direct evaporation of an organic compound solution on to a p-Si semiconductor wafer, and then studied the current–voltage (I–V) and capacitance–voltage (C–V) characteristics of these devices. It was seen that the aniline green organic thin film on the p-Si substrate showed a good rectifying behavior. The barrier heights (BHs) and ideality factors of all devices were extracted
from the electrical characteristics. Mean BH and ideality factor were calculated as 0.582 eV and 2.999, respectively from
the I–V characteristics. Additionally, the mean barrier height and mean acceptor doping concentration from C–V measurements were calculated as (0.61 ± 0.10) eV and (5.54 ± 0.68) × 1014 cm−3, respectively. The discrepancy in the BH values obtained from I–V and C–V characteristics has been attributed to different nature of the measurements. This can also be due to the existence of the
interfacial native oxide and the organic aniline green thin layer between the semiconductor and contacting top metal. 相似文献
7.
S. Mridha M. Dutta Durga Basak 《Journal of Materials Science: Materials in Electronics》2009,20(Z1):376-379
A series of n-ZnO/p-Si thin film heterojunctions have been fabricated by a low cost sol–gel technique for different ZnO film thicknesses and
the dark as well as photo current–voltage (I–V) characteristics have been investigated in details. The heterojunction with ZnO thickness of 0.46 μm shows the best diode
characteristics in terms of rectification ratio, I
F/I
R = 5.7 × 103 at 5 V and reverse leakage current density, J
R = 7.6 × 10−5 A cm−2 at −5 V. From the photo I–V curves and wavelength dependent photocurrent of the heterojunctions, it is found that the junction with 0.46 μm ZnO thickness
shows the highest sensitivity towards both UV and visible lights. 相似文献
8.
This article describes the development of a method to measure the normal-to-plane thermal conductivity of a very thin electrically
insulating film on a substrate. In this method, a metal film, which is deposited on the thin insulating films, is Joule heated
periodically, and the ac-temperature response at the center of the metal film surface is measured by a thermo-reflectance
technique. The one-dimensional thermal conduction equation of the metal/film/substrate system was solved analytically, and
a simple approximate equation was derived. The thermal conductivities of the thermally oxidized SiO2 films obtained in this study agreed with those of VAMAS TWA23 within ± 4%. In this study, an attempt was made to estimate
the interfacial thermal resistance between the thermally oxidized SiO2 film and the silicon wafer. The difference between the apparent thermal resistances of the thermally oxidized SiO2 film with the gold film deposited by two different methods was examined. It was concluded that rf-sputtering produces a significant
thermal resistance ((20 ± 4.5) × 10−9 m2·K·W−1) between the gold film and the thermally oxidized SiO2 film, but evaporation provides no significant interfacial thermal resistance (less than ± 4.5 × 10−9 m2·K·W−1). The apparent interfacial thermal resistances between the thermally oxidized SiO2 film and the silicon wafer were found to scatter significantly (± 9 × 10−9 m2·K·W−1) around a very small thermal resistance (less than ± 4.5 × 10−9 m2·K·W−1). 相似文献
9.
I. Uzunov S. Uzunova D. Kovacheva S. Vasilev B. Puresheva 《Journal of Materials Science》2007,42(10):3353-3357
Nanosized lithiated iron oxides with 10 and 50 wt.% SiO2 were prepared by a sol–gel method using 1 M Fe(NO3)3 · 9H2O and 1 M LiNO3 aqueous solutions in a stoichiometric ratio of 1:1 and colloidal silica. Dried xerogel was calcinated at 700 °C for 4 h in
air. The X-ray data of samples synthesized using 10% and 50% SiO2 showed the presence of a mixture of two phases: α-LiFeO2 and Li1−x
Fe5O8 (0 < x ≤ 0.1) for a sample containing 10% SiO2 and LiFe(SiO3)2 and Fe2O3 (h) for a sample with 50% SiO2. The electrochemical behaviour of the compounds was investigated galvanostatically within the 0.01–3.0 V range at a current
density of 0.80 mA cm−2. The Li/Li
x
Fe
y
O
z
(10%) · SiO2 cell showed a high initial reversible capacity of 1,080 mA h g−1 and a capacity of 600 mA h g−1 at the 30th cycle. Accounting these results is the presence of a SiO2 phase which stabilizes the structure of the active mass on cycling.
The mean charge voltage (1.8 V) and the discharge voltage of 1.0 V versus Li+ reference electrode as well as the high reversible capacity indicate that this material is suitable for use as anode in lithium-ion
batteries. 相似文献
10.
J. G. Park R. Vasic J. S. Brooks J. E. Anthony 《Journal of Low Temperature Physics》2006,142(3-4):387-392
Funtionalized pentacene, 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene), field-effect transistors (FET) were
made by thermal evaporation or solution deposition methods and the temperature dependent mobility was measured. The field-effect
mobility (μFET) activation energy is gate voltage dependent. At low gate voltage, activated conduction is dominant with Ea ~ 0.27 eV, slightly
smaller than the bulk value, and the activation energy decreases with increasing gate voltage. This is ascribed to traps in
the film. A non-monotonic temperature dependence is observed at high gate voltage (VG < −30 V) with Ea ~ 60 - 170 meV at lower temperatures below the mobility maximum. Realization of simple logic gate circuits
such as NOT (inverter), NOR, and NAND is demonstrated. 相似文献
11.
A. I. Klyndyuk 《Inorganic Materials》2010,46(12):1337-1340
GdBaFeNiO5+δ has been synthesized, and its crystal structure, thermal expansion, and electrical properties have been studied. It has a
tetragonal structure (sp. gr. P4/mmm) with unit-cell parameters a = 0.3910(2) nm, c = 0.7582(6) nm, and V = 115.9(2) × 10−3 nm3 (δ = 0.53) and is a p-type semiconductor. The linear thermal expansion coefficient of GdBaFeNiO5+δ is 1.32 × 10−5, 1.72 × 10−5, and 1.37 × 10−5 K−1 in the temperature ranges 340–655, 655–870, and 870–1080 K, respectively. 相似文献
12.
Meng Wang Jianjun Li Qiang Lei Jun Yu Wenli Zhou 《Journal of Materials Science: Materials in Electronics》2011,22(8):1033-1039
Ba0.6Sr0.4TiO3 films were fabricated by RF magnetron sputtering method. The X-ray diffraction (XRD) showed that the preferred orientation
of films growing on platinum Si substrates can be tailored by sputtering pressure. The processing parameters such as sputtering
pressure and substrate temperature were optimized to obtain a developed perovskite film with (110) preferred orientation.
The polarization hysteresis loops and permittivity–voltage curves of the (110)-oriented film have been investigated,which
demonstrated that the film is in ferroelectric phase at room temperature. Besides, it had excellent fatigue properties without
polarization reduction after about 1010 switch cycles, and showed low leakage current (10−9–10−7 A/cm2) within an applied voltage of 5 V. Finally, the leakage current mechanism was studied. 相似文献
13.
A series of highly (111) oriented Pb(Nb0.01Zr0.2Ti0.8)O3 (PNZT) thin films of variant thickness were successfully achieved on Pt/Ti/SiO2/Si substrate by a sol–gel route. By introducing Pb0.8Ca0.1La0.1Ti0.975O3 (PLCT) layer between the PNZT film and Pt electrode, the PNZT film could be crystallized at as low as 500 °C. When a maximum
applied voltage is 3 V, it was found that the PNZT film with PLCT seed layer possessed higher remnant polarization (22 μC/cm2) as film thickness was scaled down to 50 nm. It was also found that enhanced pyroelectric properties could be observed in
50-nm thickness PNZT thin film due to its relatively low dielectric constant. The results demonstrated that the film thickness
could be scaled down for low voltage operations using lattice matched interface between PNZT film and PLCT seed layer on Pt/Ti/SiO2/Si substrate, and this interface optimization is the key technology for synthesizing thin PNZT films at low temperature with
good insulating and electric properties. 相似文献
14.
Jianjun Li Jun Yu Jia Li Bin Zhou Guangxing Zhou Yubin Li Junxiong Gao Yunbo Wang 《Journal of Materials Science》2009,44(12):3223-3228
Bi3.25La0.75Ti2.94V0.06O12 (BLTV) thin film was fabricated on the Pt/TiO2/SiO2/p-Si(100) substrate using sol–gel method. The microstructures and electrical properties of the film after cosubstitution
of La and V were investigated. The BLTV thin film shows less highly c-axis oriented than the BIT thin film mainly with fine rod-like grains. Raman spectroscopy shows that TiO6 (or VO6) symmetry decreases and Ti–O (or V–O) hybridization increases for V substitution. The P
r and E
c values of the BLTV thin film are 26.3 μC/cm2 and 98 kV/cm at a voltage of 12 V, respectively. The thin film also exhibits a very strong fatigue endurance up to 1010 cycles and low leakage current density. The excellent properties of the BLTV thin film are attributed to the effective decrease
or suppression of oxygen vacancies after La and V cosubstitution in the thin film. 相似文献
15.
L. Tuck M. Sayer M. Mackenzie J. Hadermann D. Dunfield A. Pietak J. W. Reid A. D. Stratilatov 《Journal of Materials Science》2006,41(13):4273-4284
Silicon stabilized tricalcium phosphate (Si-TCP) is formed, among other phases, as a result of sintering hydroxyapatite (HA)
in the presence of silica (SiO2) at >800°C. Calcium phosphate films sintered at 1000°C on quartz substrates are examined with and without additional SiO2 added to the starting precipitate. Data from transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy
(XPS) separate the undoped film morphology into a surface layer with a monoclinic crystal structure P21/a characteristic of α or Si-tricalcium phosphate and grain size in the range 100–1000 nm and a substrate layer with a crystal structure which is
predominantly apatitic P63/m and grain size in the range 30–100 nm. The silicon content is greatest in the substrate layer. The addition of SiO2 to the film material during fabrication induces a more uniform grain size of 10–110 nm and a higher Si content. The structural
and phase evolution of these films suggests the nucleation of α-TCP by the local formation of Si-TCP at a SiO2-hydroxyapatite interface. The results are consistent with X-ray diffraction studies and are explained by a model of nucleation
and growth developed for bulk powders. 相似文献
16.
A. T. Filip J. J. H. M. Schoonus H. J. M. Swagten B. Koopmans W. J. M. de Jonge F. Karouta E. J. van Geluk W. van Roy J. de Boeck 《Journal of Superconductivity and Novel Magnetism》2005,18(3):379-384
Herein we discuss our approach to realizing all electrical spin injection and detection in GaAs. We propose a lateral geometry,
with two ferromagnetic electrodes crossing an n-doped GaAs channel. AlO
x
tunnel barriers are to be used in order to overcome the impedance mismatch and different widths of the two electrodes ensure
different coercive fields. We present a detailed theoretical analysis of the expected magnetoresistance. Differences in behavior
between lateral and vertical devices, the influence of the applied bias (electric field), and opportunities offered by different
measurement geometries were explored. The MBE grown wafer consisted of 100 nm Al0.3Ga0.7As, acting as confinement layer, 100 nm n-doped (4 × l017 cm−3) GaAs, 3 nm n++ GaAs (1021 cm−3), to suppress Schottky barrier formation, and 1.5 nm Al. The Al was oxidized naturally in order to obtain tunnel barriers.
By making use of in-situ shadow masks, a 0.1 mm wide channel is defined by covering the rest of the sample by insulating SiO2, followed by deposition of Ta bonding pads. Finally, 500 and 1000 nm wide CoFe electrodes crossing the GaAs channel are obtained
by e-beam lithography and sputtering. We show that the I–V characteristics of the CoFe/AlO
x
/GaAs interface are consistent with tunneling as the main injection mechanism. However, the resistance-area (5 × 109 Ω μm2) of our barriers is too high compared to the GaAs conductance (50 Ω square resistance) leading to a strong suppression of
magnetoresistance. Further experiments are in progress toward optimizing barrier and channel impedance matching. 相似文献
17.
Cerium oxide (CeO2) thin films have been prepared by electron beam evaporation technique onto glass substrate at a pressure of about 6 × 10−6 Torr. The thickness of CeO2 films ranges from 140–180 nm. The optical properties of cerium oxide films are studied in the wavelength range of 200–850
nm. The film is highly transparent in the visible region. It is also observed that the film has low reflectance in the ultra-violet
region. The optical band gap of the film is determined and is found to decrease with the increase of film thickness. The values
of absorption coefficient, extinction coefficient, refractive index, dielectric constant, phase angle and loss angle have
been calculated from the optical measurements. The X-ray diffraction of the film showed that the film is crystalline in nature.
The crystallite size of CeO2 films have been evaluated and found to be small. The experimental d-values of the film agreed closely with the standard values. 相似文献
18.
SiB4±x
and SiB6 plates were prepared by chemical vapour deposition (CVD) using SiCl4, B2H6 and H2 gases under the conditions of deposition temperatures (T
dep) from 1323–1773 K, total gas pressures (P
tot) from 4–40 kPa and B/Si source gas ratio (m
B/Si=2B2H6/SiCl4) from 0.2–2.8. The effects of CVD conditions on the morphology, structure and composition of the deposits were examined.
High-purity and high-density SiB4±x
and SiB6 plates about 1 mm thick were obtained at the deposition rates of 71 and 47 nm s−1, respectively. The lattice parameter, composition and density of CVD SiB4±x
plates were dependent on their non-stoichiometry. The lattice parameter,a, was 0.6325 nm, butc ranged from 1.262–1.271 nm.The B/Si atomic ratio ranged from 3.1–5.0, and the density ranged from 2.39–2.45×103 kg m−3. The CVD SiB6 plates showed constant values of lattice parameters (a=1.444 nm,b=1.828 nm,c=0.9915 nm), composition (B/Si=6.0) and density (2.42×103 kg m−3), independent of CVD conditions. 相似文献
19.
Sreejith K. Pisharady C. S. Menon C. Sudarshanakumar 《Journal of Materials Science》2006,41(8):2417-2421
Sandwich structures of Carbazole thin films have been prepared by using vacuum deposition technique. The plot of current density
versus voltage (J–V characteristics) shows two distinct regions. In the lower voltage region ohmic conduction and in the higher voltage region
space charge limited conduction (SCLC) is observed. Number of states in the valence band (Nv) is calculated from the temperature dependence of J in the ohmic region. From the temperature dependence of J in the SCLC region trap density (Nt) and activation energy are determined. The values of Nv and Nt are in the order 1023 m−3 and 1027 m−3 respectively. The value of activation energy is nearly equal to 0.1 eV and that of the effective mobility is 4.5 × 10−7 cm2 V−1 S−1. Schottky diodes are fabricated using Aluminium (Al) as Schottky contact. It is observed that gold (Au) is more suitable
for ohmic contact compared to silver (Ag). From a semi logarithmic plot of J versus V, the barrier height (ϕb), diode ideality factor (n) and saturation current density (J0) are determined. The value of n increases and ϕb decreases on annealing. 相似文献
20.
Seonhee Jang Hyejin Cho Youngil Lee Donghoon Kim 《Journal of Materials Science》2012,47(13):5134-5140
Gold (Au) films were formed by sintering of Au nanoparticles (NPs) under gas flows of air, oxygen (O2), nitrogen (N2), or N2 bubbled through formic acid (FA/N2). The microstructure changes of the Au nanoparticulate films were studied when different atmospheres were applied. The Au
film sintered under FA/N2 showed the progressive agglomeration and grain growth with porosity in the film, while the film sintered under N2 had NPs without participating grain growth. A necking between NPs was observed in the film, however, unnecked NPs were still
found. The Au film sintered under O2 atmosphere showed the NPs agglomeration with various sizes up to 50 nm. X-ray characteristic peaks of the (111)-preferred
orientation were observed in all samples. All samples showed N–H stretching at 3200–3300 cm−1 regardless of sintering atmosphere. Hydrocarbon chains (C–H) at 2850–3000 cm−1 were detected in the film sintered under N2. For the Au film sintered under O2, C–H stretching at 2850–3000 cm−1, C–H deformation at 1350–1470 cm−1, and C–O stretching at 1200–1300 cm−1 were observed. C–O stretching at 1600–1700 cm−1 was observed for the film sintered under FA/N2 atmosphere. The electrical resistance of the film was related with microstructures and organic residual materials left in
the film. Even though either porosity or carbon residues were observed in the film, the sintering of NPs in FA/N2 or N2 showed the sheet resistance comparable to that of electroplated one. 相似文献