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1.
Rong Tu Dingheng Zheng Qingyun Sun Mingxu Han Song Zhang Zhiying Hu Takashi Goto Lianmeng Zhang 《Journal of the American Ceramic Society》2016,99(1):84-88
Φ80 mm‐diameter, highly <110>‐oriented β‐SiC wafers were ultra‐fast fabricated via halide chemical vapor deposition (CVD) using tetrachlorosilane (SiCl4) and methane (CH4) as precursors. The effects of deposition temperature (Tdep) and total pressure (Ptot) on the orientations, microstructures, and deposition rate (Rdep) were investigated. Rdep dramatically increased with increasing Tdep where maximum Rdep was 930 μm/h at Tdep = 1823 K and Ptot = 4 kPa, leading to a maximum of 1.9 mm in thickness in 2 h deposition. The <110>‐oriented β‐SiC was obtained at Tdep > 1773 K and Ptot = 1–4 kPa. Growth mechanism of <110>‐oriented β‐SiC has also been discussed under consideration of crystallographic planes, surface energy, and surface morphology. 相似文献
2.
Fast preparation of (111)‐oriented β‐SiC films without carbon formation by laser chemical vapor deposition from hexamethyldisilane without H2
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Qingfang Xu Peipei Zhu Qingyun Sun Rong Tu Song Zhang Meijun Yang Qizhong Li Ji Shi Haiwen Li Lianmeng Zhang Takashi Goto Mingxu Han Jiasheng Yan Shusen Li Hitoshi Ohmori 《Journal of the American Ceramic Society》2018,101(4):1471-1478
(111)‐oriented β‐SiC films were prepared by laser chemical vapor deposition using a diode laser (wavelength: 808 nm) from a single liquid precursor of hexamethyldisilane (Si(CH3)3–Si(CH3)3, HMDS) without H2. The effects of laser power (PL), total pressure (Ptot) and deposition temperature (Tdep) on the microstructure, carbon formation and deposition rate (Rdep) were investigated. β‐SiC films with carbon formation and graphite films were prepared at PL ≥ 170 W and Pto ≥ 1000 Pa, respectively. Carbon formation strongly inhibited the film growth. β‐SiC films without carbon formation were obtained at Ptot = 400‐800 Pa and PL = 130‐170 W. The maximum Rdep was about 50 μm·h?1 at PL = 170 W, Ptot = 600 Pa and Tdep = 1510 K. The investigation of growth mechanism shows that the photolytic of laser played an important role during the depositions. 相似文献
3.
Effect of Pressure on Microstructure of <111>‐Oriented β‐SiC Films: Research via Electron Backscatter Diffraction
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Song Zhang Qingfang Xu Qingyun Sun Peipei Zhu Rong Tu Zhiying Hu Mingxu Han Takashi Goto Lianmeng Zhang Jiasheng Yan Shusen Li 《Journal of the American Ceramic Society》2015,98(12):3713-3718
Scanning electron microscopy (SEM) and high‐resolution electron backscatter diffraction (EBSD) has been employed to study the microstructure development of <111 > ‐oriented β‐SiC films prepared by laser chemical vapor deposition (LCVD) with various total pressure (Ptot). The Surface morphology of films evolved from pyramids with sixfold symmetry to needlelike structure by increasing the Ptot. The EBSD results indicated that the higher Ptot (800 Pa) led to the lower neighbor‐pair misorientation and large in‐plane domains in β‐SiC films. 相似文献
4.
High‐speed heteroepitaxial growth of 3C‐SiC (111) thick films on Si (110) by laser chemical vapor deposition
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Qingyun Sun Peipei Zhu Qingfang Xu Rong Tu Song Zhang Ji Shi Haiwen Li Lianmeng Zhang Takashi Goto Jiasheng Yan Shusen Li 《Journal of the American Ceramic Society》2018,101(3):1048-1057
3C‐SiC (111) thick films were grown on Si (110) substrate via laser chemical vapor deposition (laser CVD) using hexamethyldisilane (HMDS) as precursor and argon (Ar) as dilution gas. The 3C‐SiC (111) polycrystalline films were prepared at deposition temperature (Tdep) of 1423‐1523 K, whereas the 3C‐SiC (111) epitaxial films were obtained at 1573‐1648 K with the thickness of 5.40 to 9.32 μm. The in‐plane relationship was 3C‐SiC [‐1‐12]//Si [001] and 3C‐SiC [‐110]//Si [‐110]. The deposition rates (Rdep) were 16.2‐28.0 μm/h, which are 2 to 100 times higher than that of 3C‐SiC (111) epi‐grown on Si (111) by conventional CVD. The growth mechanism of 3C‐SiC (111) epitaxial films has also been proposed. 相似文献
5.
Using a sol‐gel method Pb0.8Ba0.2ZrO3 (PBZ) thin film with a thickness of ~320 nm was fabricated on Pt(111)/TiOx/SiO2/Si substrate. The analysis results of XRD, SEM, and dielectric properties revealed that this thin film is a (111)‐oriented nano‐scaled antiferroelectric and ferroelectric two‐phase coexisted relaxor. Calculations of dielectric tunability (η) and figure‐of‐merit (FOM) at room temperature display a maximum value of 75% at E = 560 kV/cm and ~236, respectively. High‐temperature stability (η > 75% and FOM > 230 at 560 kV/cm in the range from 300 to 380 K) and high breakdown dielectric strength (leakage current < 1 nA at 598 kV/cm) make the PBZ thin film to be an attractive material for applications of tunable devices. 相似文献
6.
《Journal of the European Ceramic Society》2017,37(2):509-515
Highly oriented β-SiC bulks with high hardness were fabricated by halide laser chemical vapor deposition (HLCVD) using SiCl4, CH4 and H2 as precursors. The effects of total pressure (Ptot) and deposition temperature (Tdep) on the preferred orientation, microstructure, deposition rate (Rdep) and micro-hardness were investigated. The 〈110〉-oriented β-SiC bulks were obtained at low Ptot (2–4 kPa), non-oriented β-SiC bulks were obtained at mediate Ptot (6 kPa), and 〈111〉-oriented β-SiC bulks were obtained at high Ptot (10–40 kPa), exhibiting faceted, cauliflower-like and six-fold pyramid-like microstructure, respectively. The maximum Rdep of 〈111〉- and 〈110〉-oriented β-SiC bulks were 3600 and 1300 μm/h at, respectively. The activation energy obtained by the plot of lgRdep-Tdep−1 is 170 to 280 kJ mol−1, showing an exponential relation with PSi. The Vickers micro-hardness of β-SiC bulks increased with increasing Ptot and showed the highest value of 35 GPa at Ptot = 40 kPa with a complete 〈111〉 orientation. 相似文献
7.
Rui Ding Danyang Wang Dewei Chu Sean Li 《Journal of the American Ceramic Society》2013,96(11):3530-3535
Orientation‐engineered (La, Ce) cosubstituted 0.94(Bi0.5Na0.5)TiO3–0.06BaTiO3 thin films were epitaxially deposited on CaRuO3 buffered (LaAlO3)0.3(Sr2AlTaO6)0.35 single‐crystal substrates by pulsed laser deposition. The ferroelectric, piezoelectric, dielectric, and leakage current characteristics of the thin films were significantly affected by the crystallographic orientation. We found that the (001)‐oriented film exhibited the best ferroelectric properties with remnant polarization Pr = 29.5 μC/cm2 and coercive field Ec = 7.4 kV/mm, whereas the (111)‐oriented film demonstrated the largest piezoelectric response and dielectric permittivity. The bipolar resistive switching behavior, which is predominantly attributed to a combined effect of ferroelectric switching and formation/rupture of conductive filaments, was observed. The conduction mechanisms were determined to be ohmic conduction and Poole–Frenkel emission at high‐ and low‐resistance states, respectively, in all the films. 相似文献
8.
Hong Cheng Meijun Yang Youfeng Lai Mingwei Hu Qizhong Li Rong Tu Song Zhang Mingxu Han Takashi Goto Lianmeng Zhang 《Journal of the European Ceramic Society》2018,38(9):3057-3063
Transparent and highly oriented 3C-SiC bulks were speedily fabricated at deposition temperature (Tdep) of 1623?K by halide laser chemical vapor deposition (HLCVD). The effect of total pressure (Ptot) on the optical transmittance, preferred orientation, microstructure, deposition rate (Rdep) and micro-hardness were investigated. The maximum Rdep of the transparent 3C-SiC reached 2450?μm/h at Ptot?=?10?kPa. With an increase in Ptot, the transmittance of 3C-SiC bulks increased firstly, and then decreased. At Ptot?=?10?kPa, 3C-SiC bulk, a highly <111>-oriented and low density of defects, showed the highest transmittance, greater than 55% in the wavelength range of 800–1100?nm. At Ptot?=?4?kPa and 20?kPa, 3C-SiC bulks showed much lower transmittance, in which contained poorly oriented grains and numerous defects. The Vickers micro-hardness of 3C-SiC bulks increased with increasing Ptot and showed the highest value of 34.8?GPa at Ptot?=?40?kPa. 相似文献
9.
Highly (100)‐Oriented Bi(Ni1/2Hf1/2)O3‐PbTiO3 Relaxor‐Ferroelectric Films for Integrated Piezoelectric Energy Harvesting and Storage System
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Zhenkun Xie Bin Peng Jie Zhang Xiaohua Zhang Zhenxing Yue Longtu Li 《Journal of the American Ceramic Society》2015,98(10):2968-2971
Highly (100)‐oriented 0.38Bi(Ni1/2Hf1/2)O3‐0.62PbTiO3 relaxor‐ferroelectric films were fabricated on Pt(111)/Ti/SiO2/Si(111) substrates by introducing a lead oxide seeding layer. A moderate relative permittivity , a low dissipation factor (tan δ < 5%), and strong relaxor‐like behavior (γ = 0.74) over a broad temperature region were observed. The energy storage density of approximately 45.1 ± 2.3 J/cm3 was achieved for films with (100) preferential orientation, which is much higher than the value ~33.5 ± 1.7 J/cm3 obtained from films with random orientation. Furthermore, the PbO‐seeded films are more capable of providing larger piezoelectric response (~113 ± 10 pm/V) compared to the films without seeds (~85 ± 8 pm/V). These excellent features indicate that the highly (100)‐oriented 0.38Bi(Ni1/2Hf1/2)O3‐0.62PbTiO3 films could be promising candidates for applications in high‐energy storage capacitors, high‐performance MEMS devices, and particularly for potential applications in the next‐generation integrated multifunctional piezoelectric energy harvesting and storage system. 相似文献
10.
In this study, ilmenite‐MgTiO3 films were sputtered on p‐type Si(111) substrates and the extrinsic effects, such as grain size, crystallinity, and orientation of photoluminescence (PL) properties of the films are discussed. To reduce the effect of oxygen vacancies (act as shallow defects) on PL emissions in the films, oxygen (O2) was introduced as the sputtering gas and the excitation light source (λ = 532 nm) which has a corresponding energy (hν = 2.33 eV) below the shallow defect states was used. In this study, intense near‐infrared (NIR) PL emission centered at 810.1 nm at room temperature can be observed when the MgTiO3 thin films exhibit the preferred (003)‐orientation and accompanied by the presence of hexagon‐shaped grains. In this study, the experiment results reveal that the NIR emission intensity of MgTiO3 films highly depend on crystal orientation and/or grain morphology. 相似文献
11.
In this work, undoped Mg2TiO4 thin films were fabricated on p‐type Si(111) substrates by the sol–gel method, and the red photoluminescence (PL) of the films is introduced and discussed. According to the experimental results, the red emission appears when the films have been thermally treated at higher temperatures, which have a long range and well‐organized crystalline arrangement. Furthermore, to have better realization of the red emission mechanism of Mg2TiO4 films, the optical band gap of Mg2TiO4 (EgMg2TiO4) was estimated at ~3.7 eV; furthermore, 325 nm (corresponding energy, hν = 3.82 eV > EgMg2TiO4) and 633 nm (corresponding energy, hν = 1.96 eV < EgMg2TiO4) excited light sources were used to clarify the position of the defect levels. In addition, the influence of annealing atmospheres (O2, air, and vacuum) on the red emission of our samples is also discussed. A significant variety of red emissions can be found between these annealing conditions: the red emission can be effectively enhanced by O2 annealing, but weakened by vacuum annealing. Results reveal that the red emission of Mg2TiO4 thin films may be highly dependent on the completeness of the O–X–O (X = Mg, Ti) bonds. 相似文献
12.
Peipei Zhu Qingfang Xu Ruyi Chen Song Zhang Meijun Yang Rong Tu Lianmeng Zhang Takashi Goto Jiasheng Yan Shusen Li 《Journal of the American Ceramic Society》2017,100(4):1634-1641
β‐SiC thin films have been epitaxially grown on Si(001) substrates by laser chemical vapor deposition. The epitaxial relationship was β‐SiC(001){111}//Si(001){111}, and multiple twins {111} planes were identified. The maximum deposition rate was 23.6 μm/h, which is 5‐200 times higher than that of conventional chemical vapor deposition methods. The density of twins increased with increasing β‐SiC thickness. The cross section of the films exhibited a columnar structure, containing twins at {111} planes that were tilted 15.8° to the surface of substrate. The growth mechanism of the films was discussed. 相似文献
13.
《Ceramics International》2016,42(8):9981-9987
Epitaxial (100) and (111) SrTiO3 films were prepared on (100) and (111) MgO single-crystal substrates, respectively, using laser chemical vapor deposition. The effect of deposition temperature (Tdep) on the orientation and microstructure of the SrTiO3 films was investigated. On the (100) MgO substrates, SrTiO3 films showed a (111) orientation at a low Tdep of 1023 K. (100) SrTiO3 films, which were epitaxially grown at Tdep=1123–1203 K, had dense cross sections and flat surfaces with rectangular-shaped terraces. On the (111) MgO substrates, (111) SrTiO3 films were epitaxially grown at Tdep=983–1063 K; however, these films' orientations became random at high Tdep of 1063–1113 K. The (111) SrTiO3 films consisted of columnar grains with triangular pyramidal caps. The deposition rates of the epitaxial (100) and (111) SrTiO3 films were 13–25 and 18–32 μm h−1, respectively, which is 5–530 times higher than those obtained by MOCVD. 相似文献
14.
Renhuai Wei Hongbin Jian Xianwu Tang Jie Yang Ling Hu Li Chen Jianming Dai Xuebin Zhu Yuping Sun 《Journal of the American Ceramic Society》2013,96(8):2396-2401
Highly c‐axis‐oriented Ca3Co4?xCuxO9+δ (x = 0, 0.1, 0.2, and 0.3) thin films were prepared by chemical solution deposition on LaAlO3 (001) single‐crystal substrates. X‐ray diffraction, field‐emission scanning electronic microscopy, X‐ray photoelectron spectroscopy, and ultraviolet‐visible absorption spectrums were used to characterize the derived thin films. The solubility limit of Cu was found to be less than 0.2, above which [Ca2(Co0.65Cu0.35)2O4]0.624CoO2 with quadruplicated rock‐salt layers was observed. The electrical resistivity decreased monotonously with increasing Cu‐doping content when x ≤ 0.2, and then slightly increased with further Cu doping. The Seebeck coefficient was enhanced from ~100 μV/K for the undoped thin film to ~120 μV/K for the Cu‐doped thin films. The power factor was enhanced for about two times at room temperature by Cu doping, suggesting that Cu‐doped Ca3Co4O9+δ thin films could be a promising candidate for thermoelectric applications. 相似文献
15.
Structural,Electrical, and Ferroelectric Properties of Nb‐Doped Na0.5Bi4.5Ti4O15 Thin Films
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Chinnambedu Murugesan Raghavan Jin Won Kim Sang Su Kim 《Journal of the American Ceramic Society》2015,98(10):3153-3158
Ferroelectric Na0.5Bi4.5Ti4O15 (NaBTi) and donor Nb‐doped Na0.5Bi4.5Ti3.94Nb0.06O15 (NaBTiNb) thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates using a chemical solution deposition method. The doping with Nb5+‐ions leads to tremendous improvements in the ferroelectric properties of the NaBTiNb thin film. Room‐temperature ferroelectricity with a large remnant polarization (2Pr) of 64.1 μC/cm2 and a low coercive field (2Ec) of 165 kV/cm at an applied electric field of 475 kV/cm was observed for the NaBTiNb thin film. The polarization fatigue study revealed that the NaBTiNb thin film exhibited good fatigue endurance compared with the NaBTi thin film. Furthermore, the NaBTiNb thin film showed a low leakage current density, which was 1.48 × 10?6 A/cm2 at an applied electric field of 100 kV/cm. 相似文献
16.
Greatly enhanced photocurrent in inorganic perovskite [KNbO3]0.9[BaNi0.5Nb0.5O3‐σ]0.1 ferroelectric thin‐film solar cell
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Jian Chen Weijie Pei Guang Chen Qingfeng Zhang Yinmei Lu Haitao Huang Mingkai Li Yunbin He 《Journal of the American Ceramic Society》2018,101(11):4892-4898
Inorganic perovskite [KNbO3]0.9[BaNi0.5Nb0.5O3‐σ]0.1 (KBNNO) ferroelectric thin films with narrow band gap (1.83 eV) and high room‐temperature remnant polarization (Pr = 0.54 μC/cm2) was grown successfully on the Pt(111)/Ti/SiO2/Si(100) substrates by pulsed laser deposition. Ferroelectric solar cells with a basic structure of ITO/KBNNO/Pt were further prepared based on these thin films, which exhibited obvious external‐poling dependent photovoltaic effects. When the devices were negatively poled, the short‐circuit current and open‐circuit voltage were both significantly higher than those of the devices poled positively. This is attributed to enhanced charge separation under the depolarization field induced by the negative poling, which is superimposed with the built‐in field induced by the Schottky barriers at the interfaces between KBNNO and the two electrodes. When a poling voltage of ‐1 V was applied, the device showed a short‐circuit current as high as 27.3 μA/cm2, which was by two orders of magnitude larger than that of the KBNNO thick‐film (20 μm) devices reported previously. This work may inspire further exploration for lead‐free inorganic perovskite ferroelectric photovoltaic devices. 相似文献
17.
Hua Yang Qian Liu Qinhua Wei Zhenzhen Zhou Jieqiong Wan Guanghui Liu Rong‐Jun Xie 《Journal of the American Ceramic Society》2014,97(10):3164-3169
A hard template route has been successfully developed for synthesis of β‐SiAlON:Eu phosphors at low temperatures. The synthesis utilizes mesoporous silica (SBA‐15) skeleton as an active Si source, combined with the carbothermal reduction and nitridation method. It has been shown that the additional driving force from high surface area and porosity of SBA‐15 enables β‐SiAlON:Eu (with compositions of Si6?zAlz?xOz+xN8?z?x: xEu, x = 0.010–0.200 and z = 1.000) phosphors to be formed as a dominant phase at low temperature of 1400°C. The resultant β‐SiAlON:Eu phosphor powders exhibit a typical rod‐like morphology and a well dispersed state. By tailoring the Eu2+ concentration in the phosphors, a continuous change in emission band can be realized, that is a blue emission dominated for low Eu2+ concentrations and a green emission dominated for high Eu2+ doping concentrations. Furthermore, the resultant phosphors exhibit a small thermal quenching up to high temperature of 250°C. Therefore, the developed method is beneficial to synthesize LED phosphors of oxynitride systems at lower temperatures. 相似文献
18.
《Ceramics International》2020,46(17):27000-27009
Cubic silicon carbide (3C–SiC) is an excellent protective film on graphite and has been fabricated via laser chemical vapor deposition (LCVD) with an extremely high deposition rate by our research group. To understand comprehensively its growth behavior, the polycrystalline 3C–SiC thick films with the preferred orientation of <111> and <110> were characterized by diverse measurements, especially electron back-scatter diffraction (EBSD). Along the growth direction of the <110>-oriented 3C–SiC, the microstructure changed from equiaxed grains to elongated grains with <111> orientation, and eventually the <110>-oriented columnar grains. The stacking faults in the <110>-oriented 3C–SiC could be marked as <11–20>-oriented 6H–SiC. On the other hand, in the <111>-oriented 3C–SiC films, the microstructure changed from mainly equiaxed grains to large columnar grains. The high-density stacking faults in <111>-oriented 3C–SiC films may lead to the identification of the nominal 2H, 4H and 6H polytypes by Raman spectra and EBSD. The (0001) planes of 2H-, 4H–SiC are perpendicular to the growth direction, while that of 6H–SiC are parallel. 相似文献
19.
Junfeng Gu Mingyu Xiang Wei Ji Weimin Wang Hao Wang Zhengyi Fu 《Journal of the American Ceramic Society》2018,101(12):5400-5410
The usual way to prepare TaC‐TaB2 ceramics by adding B4C to TaC leads to formation of residual C, which degrades samples’ mechanical properties. To eliminate the residual C, we suggest incorporating Si together with B4C into TaC ceramics, resulting in new ultrahigh‐temperature ceramics (TaC‐TaB2‐SiC). Dense ceramics (>99%) with SiC volume fraction ranging from 15.86% to 41.04% were fabricated by reactive spark plasma sintering at 1900°C for 5 minutes. The formation of SiO2‐based transient liquid phase was evidenced by the “film” in intermediate products, which can promote densification. The fine‐grained microstructure in final products was found to be associated with the in situ formed SiC, which impeded TaC and TaB2 grains from coarsening by the pinning effect. Besides, ultrafine TaB2 grains (~100 nm) produced during the reaction and then rearranged in liquid also contributed to grain refinement. Compared to TaC‐TaB2(‐C) ceramics prepared from TaC and B4C, the acquired composites exhibit better mechanical properties, due to their fine‐grained microstructures and the elimination of residual C. 相似文献
20.
Synthesis and growth mechanism of single crystal β‐Si3N4 particles with a quasi‐spherical morphology
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Si‐Yuan Sun Yi‐Yao Ge Qi Wang Zhao‐Bo Tian Jie Zhang Wei Cui Guang‐hua Liu Ke‐Xin Chen 《Journal of the American Ceramic Society》2018,101(10):4526-4537
Single‐crystal β‐Si3N4 particles with a quasi‐spherical morphology were synthesized via an efficient carbothermal reduction‐nitridation (CRN) strategy. The β‐Si3N4 particles synthesized under an N2 pressure of 0.3 MPa, at 1450°C and with 10 mol% unique CaF2 additives showed good dispersity and an average size of about 650 nm. X‐ray photoelectron spectroscopy analysis revealed that there was no SiC or Si–C–N compounds in the β‐Si3N4 products. Selected‐area electron‐diffraction pattern and high‐resolution image indicated single crystalline structure of the typical β‐Si3N4 particles without an obvious amorphous oxidation layer on the surface. The growth mechanism of the quasi‐spherical β‐Si3N4 particles was proposed based on the transmission electron microscopy and energy dispersive X‐ray spectroscopy characterization, which was helpful for controllable synthesis of β‐Si3N4 particles by CRN method. Owing to the quasi‐spherical morphology, good dispersity, high purity, and single‐crystal structure, the submicro‐sized β‐Si3N4 particles were promising fillers for preparing resin‐based composites with high thermal conductivity. 相似文献