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1.
Abstract Bi–layered ferroelectric SrBi2Ta2O9 (SBT) films were successfully prepared on Pt/Ti/SiO2/Si substrates at 650°C by a modified rf magnetron sputtering technique. The SBT films annealed for 1 h in O2 (760 torr) and again for 30 min in O2 (5 torr) at 650°C show a average grain size of about 49 nm. The SBT films annealed at 65 0°C have a remanent polarization (Pr) of 6.0 μC/cm2 and coercive field (Ec) of 36 kV/cm at an excitation voltage of 5 V. The films showed fatigue–free characteristics up to 4.0 × 1010 switching cycles under 5 V bipolar pulse. The retention characteristics of SBT films looked very promosing up to 1.0 × 105 s. 相似文献
2.
Abstract We demonstrate the ferroelectric behavior of Sr0.8Bi2.2Ta2O9 (SBT) films grown on Si(100) substrates by using lanthanum aluminate (LaAlO3) buffer layers. LaAlO3 films were prepared by vacuum evaporation method. Then, they were subjected to ex situ dry N2 annealing in a rapid thermal annealing (RTA) furnace. From the capacitance-voltage (C-V) measurement, the dielectric constant of LaAlO3 was estimated to be 20~25. On these substrates, SBT films (210nm) were deposited by sol-gel method and they were characterized by XRD analysis after annealing under various conditions. It was found from C-V characteristics that the memory window of an SBT film annealed at 750°C for 30min in O2 atmosphere was about 3.0V for the voltage sweep of ±10V. It was also found from the retention measurement that the capacitance values of the SBT film annealed at 750°C did not change over 12hours. It is concluded from these results that the SBT/LaAlO3/Si(100) structure is one of the most promising structures for realizing MFISFETs (metal-ferroelectric-insulator-semiconductor field-effect-transistors). 相似文献
3.
Taekjib Choi Si Won Kim Kyung Sun Yoon Young Sung Kim Jaichan Lee 《Integrated ferroelectrics》2013,141(1):163-170
[(Y0.95,Bi0.05)MnO3] (YBM) films have been grown on Y2O3 buffered Si (001) by pulsed-laser deposition (PLD). We have compared the structural and dielectric properties of YBM films with those of typical YMnO3 films from the viewpoint of lowering the process temperature. The highly c-axis oriented YBM film have been obtained on Y2O3/Si (001) at 700°C, which is a significantly reduced growth temperature from that of typical YMnO3 films (850°C). The Bi modification was effective for the low temperature processing of YBM films. These highly c-axis oriented YBM films was obtained only at high ambient oxygen pressures, for example above 100 mTorr, contrary to YMnO3 films which requires low ambient oxygen pressure for the growth of c-axis preferred orientation. The dielectric constant and dissipation factor was 29 and 0.017 at 1 MHz, respectively. The memory window due to ferroelectric polarization switching was found in a capacitance-voltage (C-V) characteristic. The YBM/Y2O3/Si structure with above characteristics of YBM films exhibited the C-V memory window of 1.2 V at a sweep voltage of 5 V. The flat-band voltage shifted symmetrically with increasing the sweep voltage up to 8 V due to little charge injection from Si. As a result, the memory window increased progressively with increasing the sweep voltage and amounted to 2 V at a sweep voltage of 8 V. The leakage current density was below 5 × 10?7 A/cm2 at a bias voltage of 8 V. 相似文献
4.
Comparative studies on the electrical properties of a metal-ferroelectric-insulator-semiconductor field effect transistor were conducted using pulsed laser ablated ferroelectric Bi3.25La0.75Ti3O12 (BLT) thin films deposited on SiO2/Si substrates with different SiO2 thicknesses. The SiO2 layer was prepared on n-type Si substrates by dry oxidation at a temperature of 800°C. Small angle x-ray reflectivity studies were used to measure the SiO2 thickness. The capacitance-voltage (C-V) measurements revealed that the films showed good interfacial properties. Shifts in flatband voltages were observable, but were effectively reduced by deposition of the ferroelectric films. Au/BLT/SiO2/Si diodes with 8 nm SiO2 layer showed to be stable with relatively large memory window values of about 0.3 V, 2.5 V, 5.0 V, and 7.0 V, at increasing bias voltages of ±5 V, ±7 V, ±10 V, and ±12 V, respectively. 相似文献
5.
The growth of dielectric layers on silicon substrates has attracted a great deal of recent interest given their potential applicability in the fabrication of high quality silicon-on-insulator (SOI) structures, high density capacitor devices, and stable buffer layers between silicon and other materials. In this study, nanocrystalline CeO2 films were deposited on n-type (100) silicon substrates using pulsed laser deposition (PLD) to form a gate dielectric for a Pt/n-Si/CeO2/Pt MOS device. XRD, AFM and FESEM measurements were used to characterize the crystal structure and grain size of the CeO2 films. The electrical properties of the device structure were examined by capacitance-voltage (C-V) and impedance spectroscopy measurements. The CeO2 films exhibited an activated conductivity, characterized by an activation energy Ea = 0.45 eV. An estimated room temperature electron mobility e of 2.8 × 10– 7 cm2/Vs leads to a corresponding electron concentration n of 5.5 × 1017 cm– 3. In contrast to conventional MOS capacitors, we find an additional capacitive contribution under strong accumulation conditions as a result of space charge effects inside the CeO2 thin film. 相似文献
6.
Katsuyoshi Matsuura Masaaki Nakabayashi Tetsuro Tamura Koichiro Honda Seigen Ohtani 《Integrated ferroelectrics》2013,141(2-4):139-149
Abstract PZT capacitor with direct contact between Si substrate and bottom electrode of the capacitor was obtained with Ir/IrO2/Ir/Ti electrode, by crystallizing sol-gel PZT thin film using RTA (650°CC 30 sec.). Contact resistance for hole diameter of 0.72 μm was 19 Ω. It was observed by cross-sectional TEM that Ti silicide was formed at the interface, but there was not oxygen diffusion from PZT thin film. Fatigue property of the PZT thin film was improved by RTA compared with furnace annealed film (600°CC 60 min.). The absolute value of the remnant polarization was 13 μC/cm2 for both films, but it did not degrade until 108 cycles of switching for the film by RTA, while it degraded before 105 cycles for furnace annealed film. 相似文献
7.
Xinhua Zhu Tao Zhu Aidong Li Tao Yu Zhguo Liu Naiben Ming 《Integrated ferroelectrics》2013,141(1-4):195-203
Abstract In this work, the microstructural defects in SrBi2Ta2O9 (SBT) ferroelectric thin films were investigated at the atomic-scale by high-resolution transmission electron microscopy (HRTEM). A stacking fault with an extra inserted Bi-O plane normal to the c-axis was observed in SBT film with 10mol% excess bismuth prepared by metalorganic deposition. Edge dislocations with an average space about 3nm were observed at the small misorientation angle (8.2°) tilt grain boundary of SBT film with (001)-orientation prepared by pulsed laser deposition. The Burgers vector b for the edge dislocation was determined to be 1/2[110]α0, where α0 is the parameter of SBT unit cell. Chemical compositions of grains and grain boundaries in SBT films annealed in forming gas at 450°C and 500°C for 60 minutes were analyzed by using energy dispersive spectra at the nano-scale. Effects of the microstructural defects and microchemistry of the grain boundaries on the leakage current of SBT films are briefly discussed. 相似文献
8.
Kwi Young Yun Jeong Seog Kim Soon Gil Yoon Chae Il Cheon 《Integrated ferroelectrics》2013,141(1-5):163-170
Abstract YMnO3 thin films were prepared on p-Si(111) and Y2O3/p-Si(111) substrates by chemical solution deposition and annealed at 800°C for 1 hour under the oxygen pressure of 2 Torr. The YMnO3 thin films showed good crystallinity and c-axis preferred orientation. Effects of Ar post-annealing on electrical properties were examined in Pt/YMnO3/p-Si and Pt/YMnO3/Y2O3/p-Si structures. Leakage current densities decreased considerably by Ar post-annealing. The Pt/YMnO3/p-Si and Pt/YMnO3/Y2O3/p-Si showed clockwise C-V hysteresis induced by ferroelectric polarization after Ar post-annealing and memory windows of MFS and MFIS structure were 1.1V and 0.6V, respectively. 相似文献
9.
Abstract Bismuth-layer-structured ferroelectric thin films, SrBi2Ta2O9 and Bi4Ti3O12, have been prepared by laser ablation method on both Pt sheets and Si wafers at low temperatures of 400 ~ 500°C. These thin films have been characterized by XRD, XPS, AFM, C-V, D-E hysteresis and J-V measurement. SrBi2Ta2O9 thin films have a good (105) preferential orientation, and Bi4Ti3O12 thin films have (117) and c-axis orientation on these substrates. Ferroelectric film-SiO2-Si structures show good C-V hysteresis curve owing to Si surface potential controlled by the D-E hysteresis. D-E hysteresis is obtained in Bi4Ti3O12 thin film prepared on Pt sheet, and the remnant polarization and the coercive force are 7.5 μC/cm2 and 72 kV/cm, respectively. 相似文献
10.
Degradation mechanisms of SrBi2Ta2O9 ferroelectric thin film capacitors during forming gas annealing
Walter Hartner Peter Bosk Günther Schindler Herbert Schroeder Rainer Waser Christine Dehm 《Integrated ferroelectrics》2013,141(1-4):341-350
Abstract The effects of annealing in forming gas (5% hydrogen, 95% nitrogen; FGA) are studied on spin coated SrBi2Ta2O9 (SBT) thin films. SBT films on platinum bottom electrode are characterized with and without platinum top electrode by Scanning Electron Microscopy (SEM), Auger Electron Spectroscopy (AES), High Temperature X-Ray Diffraction (HT-XRD) and Secondary Ion Mass Spectrometry (SIMS). High Temperature X-Ray Diffraction (HT-XRD) of blanket Ti/Pt/SBT films in forming gas revealed that the bismuth layered perovskite structure of the SBT is stable up to approx. 500°C. SIMS analysis of Pt/SBT/Pt samples annealed in deuterated forming gas (5% D2, 95% N2) showed that the hydrogen accumulates in the SBT layer and at the platinum interfaces next to the SBT. After FGA of blanket SBT films, tall platinum-bismuth whiskers are seen on the SBT surface. Performing the FGA of the whole Pt/SBT/Pt/Ti stack, two different results are found. For the samples with a high temperature annealing (HTA) step in oxygen after top electrode patterning, top electrode peeling is observed after FGA. For the samples without a HTA step after top electrode patterning, no peeling is observed after FGA. 相似文献
11.
Woong-chul Shin Kyu-jeong Choi Eun-suck Choi Chong-man Park Soon-gil Yoon 《Integrated ferroelectrics》2013,141(1-4):27-36
Abstract The ferroelectric SBT films were deposited on Pt/Ti/SiO2/Si substrates by liquid injection metalorganic chemical vapor deposition (MOCVD) with single-mixture solution of Sr[Ta(OEt)5(dmae)]2 and Bi(C6H5)3. The Sr/Ta and Bi/Ta ratio in SBT films depended on deposition temperature and mol ratio of precursor in the single-mixture solution. At the substrate temperature of 400°C, Sr/Ta and Bi/Ta ratio were close to 0.4 and 1 at precursor mol ratio of 0.5~1.0. As-deposited film was amorphous. However, after annealing at 750°C for 30 min in oxygen atmosphere, the diffraction patterns indicated polycrystalline SBT phase. The remanent polarization (Pr) and coercive field (Ec) of SBT film annealed at 750°C were 4.7 μC/cm2and 115.7 kV/cm at an applied voltage of 5 V, respectively. The SBT films annealed at 750°C showed practically no polarization fatigue up to 1010 switching cycles. 相似文献
12.
Jong-Hyun Im Ho-Seung Jeon Joo-Nam Kim Jeong-Hwan Kim Gwang-Geun Lee Byung-Eun Park Chul-Ju Kim 《Journal of Electroceramics》2009,23(2-4):284-288
Ferroelectric SrBi2Ta2O9 (SBT) films on a p-type Si (100) wafer with a LaZrO x (LZO) buffer layer have been fabricated to form a metal-ferroelectric-insulator–semiconductor (MFIS) structure. The LZO thin film and SBT films were deposited by using a sol–gel method. The equivalent oxide thickness (EOT) value of the LZO thin film was about 8.83 nm. Also, the leakage current density of the LZO thin film is about 3.3?×?10?5 A/cm2 at bias sweeping voltage of ±5 V. SBT films were crystallized in polycrystalline phase with highly preferred (115) orientation. Also, the intensity of each pick slightly increased as thickness of SBT films increased. The C–V characteristics of Au/SBT/LZO/Si structure showed clockwise hysteresis loop. The memory window width increased as the thickness of SBT films increased. The leakage current density of Au/SBT/LZO/Si structure decreased as thickness of SBT films increased. 相似文献
13.
Koukou Suu Takeshi Masuda Yutaka Nishioka Noriakitani 《Integrated ferroelectrics》2013,141(1-4):407-418
Abstract SrBi2Ta2O9 (SBT) thin films were deposited on 6-inch Pt/Ti/SiO2/Si substrates by rf magnetron sputtering using a 12-inch ceramic SBT single target. It is found that several sputtering parameters such as argon (Ar) pressure and rf power were very effective to control the Bi content of SBT thin films which is essential for obtaining good ferroelectric properties. 相似文献
14.
In this study, radio frequency (RF) sputtering was used as the method and the layer-structured bismuth compound of SrBi4Ti4O15 + 4 wt% Bi2O3 ferroelectric ceramic was used as the target to deposit the SrBi4Ti4O15 (SBT) thin films. The addition of excess Bi2O3 content in the target ceramic was used to compensate the vaporization of Bi2O3 during the sintering and deposition processes. SBT ferroelectric thin films were deposited on Pt/Ti/SiO2/Si under optimal RF magnetron sputtering parameters with different substrate temperatures for 2 h. After that the SBT thin films were post-heated using rapid temperature annealing (RTA) method. The dielectric and electrical characteristics of the SBT thin films were measured using metal-ferroelectric-metal (MFM) structure. From the physical and electrical measurements of X-ray diffraction pattern, scanning electronic microscope (SEM), I-V curve, and C-V curve, we had found that the substrate temperature and RTA-treated temperature had large influences on the morphology, the crystalline structure, the leakage current density, and the dielectric constant of the SBT thin films. 相似文献
15.
Tao Yu Dong-Sheng Wang Di Wu Ai-Dong Li Xin-Hua Zhu An Hu 《Integrated ferroelectrics》2013,141(1-4):333-339
Abstract Ferroelectric SrBi2Ta2O9(SBT) thin films prepared by metalorganic decomposition (MOD) method were annealed in forming gas (5% hydrogen + 95% nitrogen) at different temperatures for 60 min. SEM analysis results showed that an amount of columnar structures appeared on SBT surface when the annealing temperature was up to 450°C. When the annealing temperature raised up to 500°C, these columnar structures grew along one dimension and changed into wire structures. The EDX micro-area mapping analysis result showed that Bi was concentrated in the columnar or wire structures on SBT surface. The ferroelectric property analysis results showed that the hysteresis loops still existed after 5 min forming gas processing (350°C or 400°C), but when the annealing time was longer than 10 min, the resistance of the SBT samples became too low to measure the hysteresis loops. 相似文献
16.
Abstract The reaction of tantalum ethoxide with a glycol solvent produces the interchange of the ethoxide groups with the glycol. As a result, a polymeric derivative is formed with a high resistance towards hydrolysis. Compounds of Sr(II) and Bi(II) can be added to this Ta-glycol sol, leading to strontium bismuth tantalate (SBT) precursor solutions stable in air. These solutions were spin-coated onto two substrates: Pt/TiO2/SiO2/(100)Si and Ti/Pt/Ti/SiO2/(100)Si. Crystallisation of the SBT phase was carried out by a first formation of a fluorite phase that evolves to the layered perovskite at temperatures over 600°C. During crystallisation, a larger tendency to the formation of a substrate/film interface was observed in the films deposited onto Ti/Pt/Ti/SiO2/(100)Si than onto Pt/TiO2/SiO2/(100)Si. A remanent polarisation of Pr5 μC/cm2 and a coercive field of Ec <100 kV/cm were measured in the films on Pt/TiO2/SiO2/(100)Si. These films retain its remanent polarisation, Pr, up to 105seconds and are fatigue-free up to 109 cycles. 相似文献
17.
ABSTRACT In this work, metal-ferroelectric-insulator-silicon (MFIS) devices were fabricated using HfSiON as buffer layers and their electrical properties were studied. Ultra-thin HfSiON films were fabricated by electron-beam evaporation at room temperature and post-annealed using different parameters such as temperature, time in O2. By annealing a 2 nm-thick HfSiON film at 800°C for 60s in O2, a negligible hysteresis loop and small equivalent oxide thickness of 2.3 nm were obtained with a corresponding leakage current density of 6.8 × 10? 5 A/cm2 at a voltage shifted from the flat band voltage by 1 V. In the fabrication of MFIS diodes, Sr0.8Bi2.2Ta2O9 (SBT) films with 400 nm thickness were formed by chemical solution deposition. For Pt/SBT (400 nm)/HfSiON(2 nm)/Si diodes, a memory window of 0.8 V in width was observed during double capacitance-voltage sweep between +5 and –5 V. At the same time, excellent data retention properties were observed. The high and low capacitances in the hysteresis loop were well distinguishable even after 24 h had elapsed. 相似文献
18.
Wei-Kuo Chia Ying-Chung Chen Cheng-Fu Yang San-Lin Young Wang-Ta Chiang Yu-Tarng Tsai 《Journal of Electroceramics》2006,17(2-4):173-177
Bi4Ti3O12 thin films are deposited on ITO/glass and Pt/Ti/Si(100) substrates by R.F. magnetron sputtering at room temperature. The
films are then heated by a rapid thermal annealing (RTA) process conducted in oxygen atmosphere at temperatures ranging from
550–700∘C. X-ray diffraction examination reveals that the crystalinity of the films grown on Pt/Ti/Si is better than that of the films
grown on ITO/glass under the same fabrication conditions. SEM observation shows that the films grown on Pt/Ti/Si are denser
than those grown on ITO/glass substrates. Interactive diffusion between the Bi4Ti3O12 film and the ITO film increases with the increase of annealing temperature. The optical transmittance of the thin film annealed
at 650∘C is found to be almost 100% when the effect of the ITO film is excluded. The relative dielectric constants, leakage currents
and polarization characteristics of the two films are compared and discussed. 相似文献
19.
Abstract High dielectric constant Ba0.96Ca0.04Ti0.84Zr0.16O3 (BCTZ) thin films were deposited on Pt/Ti/SiO2/Si substrates by spin on metal-organic decomposition (MOD) technique. Undoped and 0.4% Mg-doped BCTZ thin films were annealed in the temperature range from 600 to 900 °C for 1 hour in oxygen environment. The crystal structure of BCTZ thin films was analyzed by X-ray diffraction. The electrical properties of BCTZ thin films were investigated by capacitance—voltage (C—V) characteristics. Also, the electrical properties of these films were compared in conjunction with 0.4% Mg doping effect of BCTZ thin films for possible high dielectric constant material applications. 相似文献
20.
Jong-Hyun Im Ho-Seung Jeon Joo-Nam Kim Dong-Won Kim Byung-Eun Park Chul-Ju Kim 《Journal of Electroceramics》2009,22(1-3):276-280
To obtain a metal–ferroelectric–insulator–semiconductor (MFIS) structure, we fabricated ferroelectric SrBi2Ta2O9 (SBT) film on a p-type Si (100) wafer with a LaZrO x (LZO) buffer layer by means of a sol–gel technique. The sol–gel deposited LZO film according to the different annealing temperatures had a good surface morphology even though the crystalline phase was not an amorphous phase. In particular, the root-mean-squared (RMS) surface roughness of the 750-°C-annealed LZO film was about 0.365 nm and its leakage current density was about 8.2?×?10?7 A/cm2 at 10 V. A Au/SBT/LZO/Si structure with different SBT film was fabricated. The C–V characteristics of the Au/SBT/LZO/Si structure showed a clockwise hysteresis loop. The memory window width increased as the SBT film thickness increased. The 600-nm-thick SBT film was crystallized in a polycrystalline phase with a highly preferred (115) orientation. The memory window width of the 600-nm-thick SBT film was about 1.94 V at the bias sweep voltage ±9 V and the leakage current density was about 6.48?×?10?8 A/cm2 at 10 V. 相似文献