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1.
Optical properties of hexagonal boron nitride thin films deposited by radio frequency bias magnetron sputtering 下载免费PDF全文
The optical properties of hexagonal boron nitride (h-BN) thin films
were studied in this paper. The films were characterized by Fourier
transform infrared spectroscopy, UV--visible transmittance and
reflection spectra. h-BN thin films with a wide optical band gap Eg (5.86 eV for the as-deposited film and 5.97 eV for the
annealed film) approaching h-BN single crystal were successfully
prepared by radio frequency (RF) bias magnetron sputtering and
post-deposition annealing at 970~K. The optical absorption behaviour
of h-BN films accords with the typical optical absorption
characteristics of amorphous materials when fitting is made by the
Urbach tail model. The annealed film shows satisfactory structure
stability. However, high temperature still has a significant
effect on the optical absorption properties, refractive index n,
and optical conductivity σ of h-BN thin films. The
blue-shift of the optical absorption edge and the increase of Eg probably result from stress relaxation in the film under high temperatures. In addition, it is found that the refractive index
clearly exhibits different trends in the visible and ultraviolet regions.
Previous calculational results of optical conductivity of h-BN
films are confirmed in our experimental results. 相似文献
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基于安德森紧束缚模型,本文研究了无序双层六角氮化硼量子薄膜的电子性质. 数值计算结果表明在双层都无序掺杂的情况下,六角氮化硼量子薄膜的电子是局域的, 其表现为绝缘体性质;而对于单层掺杂(无论是氮原子还是硼原子)的双层六角氮化硼量子薄膜, 在能谱的带尾出现了持续的迁移率边.这就说明在单层掺杂的双层六角氮化硼量子薄膜中产生了 金属绝缘体转变.这一结果证实了有序-无序分区掺杂的理论模型,为理解及调控双层六角氮化硼量子薄膜 的电子性质提供了有益的理论指导. 相似文献
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利用感应耦合等离子体增强化学气相沉积法以Ar,He,N2和B2H6为反应气体制备了高纯立方氮化硼薄膜.用四极质谱仪对等离子体状况进行了系统的分析,发现B2H6完全被电离而N2只是部分被电离.H2和过量的N2在等离子体中生成大量中性的H原子和活化的N*2,它们与表面的相互作用严重地阻碍了立方
关键词:
立方氮化硼薄膜
等离子体
质谱 相似文献
4.
Studying the surface properties of cubic boron nitride (c-BN) thin films is very important to making it clear that its formation mechanism and application. In this paper, c-BN thin films were deposited on Si substrates by radio frequency sputter. The influence of working gas pressure on the formation of cBN thin film was studied. The surface of c-BN films was analyzed by X-ray photoelectron spectroscopy (XPS), and the results showed that the surface of c-BN thin films contained C and O elements besides B and N. Value of N/B of c-BN thin films that contained cubic phase of boron nitride was very close to 1. The calculation based on XPS showed that the thickness of hexagonal boron nitride (h-BN) on the surface of c-BN films is approximately 0.8 nm. 相似文献
5.
Cubic boron nitride (c-BN) thin films are deposited on p-type Si wafers using radio frequency (RF) sputtering and then doped by implanting S ions. The implantation energy of the ions is 19 keV, and the implantation dose is between 10 15 ions/cm 2 and 10 16 ions/cm 2 . The doped c-BN thin films are then annealed at a temperature between 400°C and 800 C. The results show that the surface resistivity of doped and annealed c-BN thin films is lowered by two to three orders, and the activation energy of c-BN thin films is 0.18 eV. 相似文献
6.
本文报道用直流平面磁控溅射法在Si片上生长c轴高度择优取向AIN薄膜的光学特性.俄歇谱分析表明薄膜是高纯的.从红外吸收光谱上分析获得晶格振动纵、横模的频率分别为2.5×10~(13)HZ和1.8×10~(13)Hz.从喇曼光谱上分析获得AIN薄膜的光学声子频率为297、512、607、656、832cm~(-1).与几种已知的纤锌矿结构二元化合物的声子频率模式类比获得AIN的光学声子模式.进一步分析表明AIN是一种静电力大于原子间各向异性力的晶体,且声子的最高频率与r~(-3/2)N~(-1/2)成正比. 相似文献
7.
Carlos Caro Carlos Lpez‐Cartes Paula Zaderenko Jos A. Mejías 《Journal of Raman spectroscopy : JRS》2008,39(9):1162-1169
We report a novel method for the fabrication of films of silver nanoparticle aggregates that are strongly attached to Si substrates (Thiol‐immobilized silver nanoparticle aggregates or TISNA). The attachment is achieved by chemically modifying the surface of a Si(100) surface in order to provide SH groups covalently linked to the substrate and then aggregating silver nanoparticles on these thiol covered surfaces. The transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) characterization show a high coverage with single nanoparticles or small clusters and a partial coverage with fractal aggregates that provide potential hot spots for surface enhanced Raman scattering (SERS). We have confirmed the SERS activity of these films by adsorbing rhodamine 6G and recording the Raman spectra at several concentrations. By using the silver‐chloride stretching band as an internal standard, the adsorbate bands can be normalized in order to correct for the effects of focusing and aggregate size, which determine the number of SERS active sites in the focal area. This allows a quantitative use of SERS to be done. The adsorption–desorption of rhodamine 6G on TISNA films is reversible. These features make our TISNA films potential candidates for their use in chemical sensors based on the SERS effect. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Van der Waals heterostructure of phosphorene and hexagonal boron nitride: First-principles modeling 下载免费PDF全文
We have studied the structural and electronic properties of a hybrid hexagonal boron nitride with phosphorene nanocomposite using ab initio density functional calculations. It is found that the interaction between the hexagonal boron nitride and phosphorene is dominated by the weak van der Waals interaction, with their own intrinsic electronic properties preserved. Furthermore, the band gap of the nanocomposite is dependent on the interfacial distance. Our results could shed light on the design of new devices based on van der Waals heterostructure. 相似文献
10.
Temporal Raman scattering measurements with 488, 532 and 632 nm excitation wavelengths and normal Raman studies by varying the power (from 30 W/cm2 to 2 MW/cm2) at 488 nm were performed on silver oxide thin films prepared by pulsed‐laser deposition. Initially, silver oxide Raman spectra were observed with all three excitation wavelengths. With further increase in time and power, silver oxide photodissociated into silver nanostructures. High‐intensity spectral lines were observed at 1336 ± 25 and 1596 ± 10 cm−1 with 488 nm excitation. No spectral features were observed with 633 nm excitation. Surface‐enhanced resonance Raman scattering theory is used to explain the complex behavior in the intensity of the 1336/1596 cm−1 lines with varying power of 488 nm excitation. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Ekaterina Vinogradova Alfredo Tlahuice‐Flores J. Jesus Velazquez‐Salazar Eduardo Larios‐Rodriguez Miguel Jose‐Yacaman 《Journal of Raman spectroscopy : JRS》2014,45(9):730-735
N‐Acetylneuraminic acid (sialic acid, Neu5Ac) has recently gained interest as a potential marker for a variety of pathophysiological processes, although no Raman study has been reported for this important biomolecule. In this paper, the vibrational properties of Neu5Ac were studied by means of Raman, surface‐enhanced Raman scattering (SERS), and density functional theory calculations. By adsorption of Neu5Ac on silver nanoparticle surface, strongly enhanced Raman intensities are obtained, allowing easy measurement of small amounts of aqueous Neu5Ac (10 µl of a 10−7 m solution) utilizing low laser power and short exposure time. The mechanism of adsorption of Neu5Ac on the silver surface is discussed on the basis of the experimental and theoretical results. This study demonstrates that SERS can provide an effective tool for development of a label‐free, rapid, and sensitive optical platform for identification of Neu5Ac. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
13.
采用基于密度泛函理论(DFT)的第一性原理计算方法,计算了多种尺寸的石墨烯和六方氮化硼纳米片的性质,系统研究了其中的量子尺寸效应.研究的最大尺寸纳米片的直径约为5.5 nm,包含816个原子.对纳米片及其边缘的几何结构、电子结构、磁性性质以及电子分布进行了深入探讨,发现石墨烯和六方氮化硼纳米片最外层原子有由锯齿形向圆形变化的趋势,使得纳米片最外层更加平滑.随着纳米片尺寸的增加,能级由分立逐渐变得连续,纳米片由孤立分子态逐渐变得接近无限的晶体;禁带宽度总体有下降的趋势,符合量子尺寸效应.纳米片存在明显的磁性,磁矩主要集中在最外层原子上,且在相对平滑的地方容易出现磁性,相对弯曲的地方不易出现磁性.当增加体系的电子数时,增加的电子主要分布在最外层,使得纳米片整体磁性呈递减的趋势;当减少体系的电子数时,减少的电子的分布逐渐由最外层向内收缩,体系的总磁矩略有增加.研究结果对石墨烯和六方氮化硼纳米片的应用有参考价值. 相似文献
14.
Influence of oxygen on the growth of cubic boron nitride thin films by plasma-enhanced chemical vapour deposition 下载免费PDF全文
Cubic boron nitride thin films were deposited on silicon
substrates by low-pressure inductively coupled plasma-enhanced
chemical vapour deposition. It was found that the introduction of
O2 into the deposition system suppresses both nucleation and
growth of cubic boron nitride. At a B2H6 concentration of
2.5\% during film deposition, the critical O2 concentration
allowed for the nucleation of cubic boron nitride was found to be
less than 1.4\%, while that for the growth of cubic boron nitride
was higher than 2.1\%. Moreover, the infrared absorption peak
observed at around 1230--1280~cm-1, frequently detected for
cubic boron nitride films prepared using non-ultrahigh vacuum
systems, appears to be due to the absorption of boron oxide, a
contaminant formed as a result of the oxygen impurity. Therefore,
the existence of trace oxygen contamination in boron nitride films
can be evaluated qualitatively by this infrared absorption peak. 相似文献
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E. Fazio F. Neri C. D'Andrea P. M. Ossi N. Santo S. Trusso 《Journal of Raman spectroscopy : JRS》2011,42(6):1298-1304
The surface‐enhanced Raman scattering (SERS) activity of silver thin films deposited by the pulsed laser ablation technique was investigated. The samples were grown in a controlled Ar atmosphere at pressures ranging between 10 and 70 Pa, and changing the number of laser pulses. Different surface morphologies, from isolated nearly spherical nanoparticles (NPs) to larger islands with smooth edges, were observed by means of scanning and transmission electron microscopies, as a function of the different deposition conditions adopted. SERS measurements were performed by soaking the samples in rhodamine 6G aqueous solutions over the concentration range between 1.0 × 10−4 and 5.0 × 10−8 M . Raman spectra were acquired using both the 632.8 and 514.5 nm excitation sources. The dependence of the SERS activity of the samples on the observed surface morphology is presented and discussed. The presence of the so called hot spots is envisaged. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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高质量宽带隙立方氮化硼薄膜的研究进展 总被引:1,自引:0,他引:1
文章着重介绍了最近研制出的高质量宽带隙立方氮化硼薄膜的三种制备方法和结构特性 :(1)用射频溅射法在Si衬底上制备出立方相含量在 90 %以上 ,Eg>6 .0eV的c-BN薄膜 ;(2 )用离子束辅助的化学气相沉积法(CVD) ,在金刚石上外延生长出立方含量达 10 0 %的单晶c -BN薄膜 ;(3)用微波电子回旋共振CVD法 (MW -ECR-CVD)在金刚石上外延生长出高纯c-BN薄膜 .这些高纯c -BN薄膜 ,可应用于制作各种半导体 (主要是高温、高频大功率 )电子器件 . 相似文献
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本文采用密度泛函B3LYP方法在6-31G*水平上,对一系列不同宽度的锯齿型和扶手椅型六角氮化硼纳米带进行了理论研究。结果表明纳米带宽度对体系的性质有规律性的影响。随着宽度的增加,纳米带不同位置的硼氮键键长差异逐步减小从而提高了整个体系的共轭性;锯齿型纳米带的能隙单调减小而扶手椅型纳米带的能隙在减小的同时出现振荡,且振幅随宽度逐渐减小。锯齿型氮化硼纳米带的化学势在特定宽度出现了极值点。前线分子轨道的分布随着宽度的增加出现了非均匀分布,呈现出向边界偏移的现象。 相似文献