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1.
We have investigated the etching properties of p- and n-type β-FeSi2 crystals grown from solution. Characteristic shapes of etch pits depending on the surface orientation was observed on the etched surface by using diluted hydrofluoric acid (5% of HF) and HF:HNO3:H2O=1:1:(2–8) solutions. However, the shapes of etch pits were independent of the conduction type and carrier density of the crystals. We also found the anisotropy of etch rates. The etch rates of the HF:HNO3:H2O=1:1:2 solution at 22°C were approximately 1.57, 1.43 and 1.09 μm/min on {1 1 1}, {1 0 0} and {0 0 1} faces of p-type β-FeSi2 crystals, respectively. 相似文献
2.
M. Lorenz H. Hochmuth M. Grundmann E. Gaganidze J. Halbritter 《Solid-state electronics》2003,47(12):2183
Ca doping of YBa2Cu3O7−δ (YBCO) is well known to enhance the critical current density in large-angle grain boundaries for example of bicrystals. However, up to now no data are available on microwave properties of epitaxial Ca-doped YBa2Cu3O7−δ thin films on r-plane sapphire with CeO2 buffer layer.Therefore, first results are presented for large-area pulsed laser deposition (PLD) grown CaxY1−xBa2Cu3O7−δ films on 3-in. diameter sapphire wafers. The PLD process is optimised for undoped YBCO thin films and shows high reproducibility for YBCO. The microwave surface resistance Rs at 8.5 GHz of Ca-doped YBCO (x=0.1) thin films shows clear reduction (up to 20%) with respect to that of YBCO for temperatures from about 20–50 K. In addition, microwave surface resistance Rs of Ca-doped YBCO is lower than that of YBCO even for enhanced microwave surface magnetic field up to about 20 mT for temperatures 20 and 40 K. 相似文献
3.
Defects introduced into SrTiO3 by auto-feeding epitaxy studied using positron annihilation technique
A. Uedono M. Kiyohara K. Shimoyama K. Yamabe T. Ohdaira R. Suzuki T. Mikado 《Materials Science in Semiconductor Processing》2003,6(5-6):367-369
Vacancy-type defects in SrTiO3 were studied by means of positron annihilation. Thin CeO2 films were grown on SrTiO3 substrates by molecular-beam epitaxy without using an oxidant; oxygen was supplied by diffusion from the substrate. This process is referred as “auto-feeding epitaxy” (AFE). The species of defects introduced into the substrate was found to be not only oxygen vacancies but also Sr-vacancies or their complexes. CeO2 films were grown also on MgO, yttria-stabilized zirconia and sapphire substrates using AFE, and these substrates were characterized by positron annihilation. 相似文献
4.
Ch. Wenger J. Dbrowski P. Zaumseil R. Sorge P. Formanek G. Lippert H.-J. Müssig 《Materials Science in Semiconductor Processing》2004,7(4-6):227
Metal–insulator–metal (MIM) capacitors with Pr2O3 as high-k material have been investigated for the first time. We varied the thickness of the Pr2O3 layers as well as the bottom electrode material. The layers are characterised using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM) and secondary ion mass spectroscopy (SIMS). Preliminary information on the interaction of water with the films was obtained from XPS and ab initio pseudopotential calculations. The electrical characterisation shows that Pr2O3 MIM capacitors can provide higher capacitance densities than Si3N4 MIM capacitors while still maintaining comparable voltage coefficients of capacitance. The Pr2O3 dielectric material seems to be suitable for use in silicon RF applications. 相似文献
5.
N. Seki K. Takakura T. Suemasu F. Hasegawa 《Materials Science in Semiconductor Processing》2003,6(5-6):307-309
[1 0 0]-oriented β-FeSi2 films were grown on Si(0 0 1) substrates by molecular beam epitaxy (MBE) with a deposited Si to Fe atomic ratio (Si/Fe ratio) varied from 1.6 to 2.8. It was found that the conduction type of the β-FeSi2 films changed from p- to n-type between the deposited Si/Fe=2.4 and 2.8. Rutherford Back Scattering (RBS) measurements revealed that the real Si/Fe ratio of β-FeSi2 is 2.0–2.1 for all the samples after 900°C annealing for 14 h, showing that stoichiometry of the grown films is almost satisfied even though the deposited Si/Fe ratio was away from stoichiometry. 相似文献
6.
W. Gehlhoff D. Azamat A. Hoffmann 《Materials Science in Semiconductor Processing》2003,6(5-6):379-383
Magnetic resonance studies of native defects in Zinc germanium diphosphide (ZnGeP2) and their energy level positions in the band gap are reviewed and first results on defects in ZnSiP2 are presented. The contribution of the dominant native defects to the optical absorption of ZnGeP2 crystals is revealed by photo-EPR investigations in combination with the first ODMR experiments. The EPR results published for Mn and Fe in the II–IV–V2 chalcopyrites are summarized. The observation of some new Mn centers and the first experimental detection of antiferromagnetic Mn–Mn coupled pairs in ZnGeP2 are presented. In addition, new results concerning Mn-induced local changes of the free parameter xf of the chalcopyrite structure at the impurity site are discussed. 相似文献
7.
The microwave dielectric properties of (1 − x)CaTiO3–xNd(Mg1/2Ti1/2)O3 (0.1 x 1.0) ceramics prepared by the conventional solid state method have been investigated. The system forms a solid solution throughout the entire compositional range. The dielectric constant decreases from 152 to 27 as x varies from 0.1 to 1.0. In the (1 − x)CaTiO3–xNd(Mg1/2Ti1/2)O3 system, the microwave dielectric properties can be effectively controlled by varying the x value. At 1400 °C, 0.1CaTiO3–0.9Nd(Mg1/2Ti1/2)O3 has a dielectric constant (εr) of 42, a Q × f value of 35 000 GHz and a temperature coefficient of resonant frequency (τf) of −10 ppm/°C. As the content of Nd(Mg1/2Ti1/2)O3 increases, the highest Q × f value of 43 000 GHz for x = 0.9 is achieved at the sintering temperature 1500 °C. 相似文献
8.
In2O3-Fe2O3 nanotubes are synthesized by an electrospinning method. The as-synthesized materials are characterized by scanning electron microscope and X-ray powder diffraction. The gas sensing results show that In2O3-Fe2O3 nanotubes exhibit excellent sensing properties to acetone and formaldehyde at different operating temperatures. The responses of gas sensors based on In2O3-Fe2O3 nanotubes to 100 ppm acetone and 100 ppm formaldehyde are 25 (240℃) and 15 (260℃), and the response/recovery times are 3/7 s and 4/7 s, respectively. The responses of In2O3-Fe2O3 nanotubes to 1 ppm acetone (240℃) and formaldehyde (260℃) are 3.5 and 1.8, respectively. Moreover, the gas sensor based on In2O3-Fe2O3 nanotubes also possesses an excellent selectivity to acetone and formaldehyde. 相似文献
9.
采用水热法和电化学沉积法,成功制备了包覆有SnO2纳米颗粒的WO3纳米棒阵列薄膜,退火处理后形成WO3/SnO2异质结复合薄膜。通过改变SnO2的沉积时间得到了复合薄膜的最佳制备条件。采用XRD,FESEM对WO3/SnO2复合薄膜的物相和形貌进行了分析,通过电化学工作站对WO3/SnO2复合薄膜的光电性能进行了研究,结果表明,电沉积时间为120 s时,WO3/SnO2复合薄膜具有最小的阻抗,且在0.6 V的偏压下光电流密度为0.46 mA/cm2,相比于单一WO3纳米棒薄膜,表现出更好的光电化学性能。 相似文献
10.
11.
Eiji MiyazakiYuji Goda Shigeru Kishimoto Takashi Mizutani 《Solid-state electronics》2011,62(1):152-155
AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors (MOSHFETs) with Al2O3 gate oxide which was deposited by atomic layer deposition (ALD) were fabricated and their performance was then compared with that of AlGaN/GaN MOSHFETs with HfO2 gate oxide. The capacitance (C)-voltage (V) curve of the Al2O3/GaN MOS diodes showed a lower hysteresis and lower interface state density than the C-V curve of the HfO2/GaN diodes, indicating better quality of the Al2O3/GaN interface. The saturation of drain current in the ID-VGS relation of the Al2O3 AlGaN/GaN MOSHFETs was not as pronounced as that of the HfO2 AlGaN/GaN MOSHFETs. The gate leakage current of the Al2O3 MOSHFET was five to eight orders of magnitude smaller than that of the HfO2 MOSHFETs. 相似文献
12.
Ho Jin Cho Young Dae Kim Dong Su Park Euna Lee Cheol Hwan Park Jun Soo Jang Keum Bum Lee Hai Won Kim Young Jong Ki Il Keun Han Yong Wook Song 《Solid-state electronics》2007,51(11-12):1529
New ZrO2/Al2O3/ZrO2 (ZAZ) dielectric film was successfully developed for DRAM capacitor dielectrics of 60 nm and below technologies. ZAZ dielectric film grown by ALD has a mixture structure of crystalline phase ZrO2 and amorphous phase Al2O3 in order to optimize dielectric properties. ZAZ TIT capacitor showed small Tox.eq of 8.5 Å and a low leakage current density of 0.35 fA/cell, which meet leakage current criteria of 0.5 fA/cell for mass production. ZAZ TIT capacitor showed a smaller cap leak fail bit than HAH capacitor and stable leakage current up to 550 °C anneal. TDDB (time dependent dielectric breakdown) behavior reliably satisfied the 10-year lifetime criteria within operation voltage range. 相似文献
13.
The electronic-energy band structures and total density of states (TDOS) for bulk BaTiO3 and SrTiO3 were calculated by the first-principles calculations using density-functional theory and local-density approximation. The calculated band structure of BaTiO3 and SrTiO3 show the energy band gaps of 1.81 and 1.92 eV at the Γ point in the Brillouin zone, respectively. The optical properties of the both perovskites in the core-level spectra are investigated by the first principles under scissor approximation. The optical constants like refractive index and extinction coefficient of both BaTiO3 and SrTiO3 were derived from the calculated real and imaginary parts of the dielectric function. The calculated spectra were compared with the experimental results for BaTiO3, SrTiO3 in good agreement. 相似文献
14.
分别采用旋涂法和水热法在FTO衬底上制备Co3O4种子层和Co3O4薄膜,再在Co3O4薄膜上水热生长Fe2O3纳米棒,获得了高质量的Co3O4/Fe2O3异质结复合材料。通过改变Fe2O3前驱体溶液浓度来改变异质结复合材料中Fe2O3组分的含量。结果表明,Fe2O3纳米棒覆盖在呈网状结构的Co3O4薄膜上,随着Fe2O3前驱体溶液浓度即Fe2O3组分含量的增加,Co3O4/Fe2O3异质结复合材料对紫外光的响应逐渐增强,当Fe2O3前驱体溶液浓度为0.015mol/L时,异质结复合材料有着很好的光电稳定性,并表现出较高的响应率(12.5mA/W)和探测率(4.4×1010Jones)。 相似文献
15.
The CH3NH3PbI3 (MAPbI3) perovskite was usually prepared by high-purity PbI2 with high cost. The low cost and low-purity PbI2 was seldom reported for fabrication of MAPbI3 because it cannot even dissolve well in widely adopted solvent of DMF. We developed an easy method to adapt low-purity PbI2 for fabrication of high quality MAPbI3 just by the simple addition of some hydrochloric acid into the mixture of low-purity PbI2, MAI and DMF. This straightforward method can not only help dissolve the low quality PbI2 by reacting with some impurities in DMF, but also lead to a successful fabrication of high-quality perovskite solar cells with up to 14.80% efficiency comparable to the high quality PbI2 precursors. 相似文献
16.
Jun-ichi Nishizawa Toru Kurabayashi Kyozo Kanamoto Takashi Yoshida Toru Oizumi 《Materials Science in Semiconductor Processing》2003,6(5-6):363-366
Plasma-enhanced chemical vapor deposition of SiO2 with well-suppressed subcutaneous oxidation is demonstrated to be a promising technology for eliminating defect generation and fabricating thin gate SiO2 films by means of a totally low-temperature process. An anomalous increase in electron density was observed in Si substrates irradiated by plasma-activated oxygen during the formation of gate SiO2 films using an ultrahigh-vacuum system. The origin of this phenomenon was related to the donors generated by a high-energy species of oxygen radicals. For a deposition process, ionized oxygen may be effective but the radicals may cause plasma-enhanced oxidation with defect generation. 相似文献
17.
利用热蒸发、氧化及金属诱导技术,具有不同截面的大尺度In2O3纳米塔被成功地合成,这些纳米塔的形貌、结构特征与诱导金属的种类(金、银或锡)、衬底和蒸发源的相对位置、生长温度以及气流速率等有较大关系。采用锡作为金属诱导,In2O3纳米塔不能被合成,这说明金属液滴在这些纳米塔的生长初期起到了非常重要的作用。In2O3纳米塔的形成归因于一个竞争性的横向和轴向生长模式,横向生长由气相-固相机理控制,而轴向生长由金属液滴辅助的气体-液体-固体生长机理控制。具有奇异的塔状结构的In2O3纳米塔在光电器件和气体传感器等方面有潜在的应用前景。 相似文献
18.
近年来,氧化铪基忆阻器因其优异的阻变性能及与CMOS工艺兼容等特点而被广泛研究。然而,氧化铪基忆阻器仍存在以下问题:1) 器件良率、可靠性、均一性不足;2) Set和Reset 过程中电流突变,导致多值特性较差。为实现氧化铪基忆阻器的性能优化及多值特性,文章在HfO2表面生长一层1~5 nm Al2O3,构造Al2O3/HfO2双介质层忆阻器,并对HfO2和Al2O3的厚度进行优化,最终得到性能显著提升的Al2O3/HfO2双介质层多值忆阻器。该器件呈现出保持性良好的10个不同电阻态(1×104 s@85℃)。由于氧离子在Al2O3层的迁移率更低,限制了氧空位细丝生长速率及宽度,且Al2O3具有热增强作用,使氧空位分布更均匀,促使氧空位细丝生成/断裂过程由突变转为渐变。该工作为进一步实现氧化铪基忆阻器的性能优化及多值特性提供了参考。 相似文献
19.
Y.C. ChangM.L. Huang Y.H. ChangY.J. Lee H.C. ChiuJ. Kwo M. Hong 《Microelectronic Engineering》2011,88(7):1207-1210
Al2O3, HfO2, and composite HfO2/Al2O3 films were deposited on n-type GaN using atomic layer deposition (ALD). The interfacial layer of GaON and HfON was observed between HfO2 and GaN, whereas the absence of an interfacial layer at Al2O3/GaN was confirmed using X-ray photoelectron spectroscopy and transmission electron microscopy. The dielectric constants of Al2O3, HfO2, and composite HfO2/Al2O3 calculated from the C-V measurement are 9, 16.5, and 13.8, respectively. The Al2O3 employed as a template in the composite structure has suppressed the interfacial layer formation during the subsequent ALD-HfO2 and effectively reduced the gate leakage current. While the dielectric constant of the composite HfO2/Al2O3 film is lower than that of HfO2, the composite structure provides sharp oxide/GaN interface without interfacial layer, leading to better electrical properties. 相似文献
20.
Dry plasma etching of sub-micron structures in a SiO2/Si/SiO2 layer system using Cr as a mask was performed in a fluorocarbon plasma. It was determined that the best anisotropy could be achieved in the most electropositive plasma. A gas composition yielding the desired SOI planar photonic crystal structures was optimized from the available process gases, Ar, He, O2, SF6, CF4, c-C4F8, CHF3, using DC bias data sets. Application of the c-C4F8/(noble gas) chemistry allowed fabrication of the desired SOI planar photonic crystal. The average etching rates for the pores and ridge waveguide regions were about 71 and 97 nm/min, respectively, while the average SiO2/Si/SiO2 to Cr etching selectivity for the ridge waveguide region was about 33:1 in case of the c-C4F8/90%Ar plasma with optimized parameters. 相似文献