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1.
超声处理对ZnO薄膜光致发光特性的影响   总被引:3,自引:0,他引:3       下载免费PDF全文
袁艳红  侯洵  高恒 《物理学报》2006,55(1):446-449
对于结晶状态好的ZnO薄膜,测量了其光致发光(PL)光谱,发射光谱中只发现了峰值波长约389 nm的近紫外光.样品进行超声处理后,发射谱中不仅观察到近紫外峰,又观察到波长约508 nm的绿光峰.绿光峰的强度比近紫外光的强度强得多,且近紫外峰红移.进一步的热处理使绿光峰大大增强.超声处理改变了ZnO薄膜的质量和结晶状态,使晶格中产生氧空位.处理过程中的热效应使得薄膜晶格振动加剧.当晶格振动加剧到一定程度,晶格中的氧脱离格点形成氧空位.510 nm左右的绿色发光峰是ZnO晶体中的氧空位产生的.薄膜的温度越高, 关键词: ZnO薄膜 超声 光致发光  相似文献   

2.
The amorphous gallium nitride thin films doped with Mn were deposited by Laser assisted Molecular Beam Epitaxy (LMBE). After annealing at different NH3 flow rates, the high-quality GaMnN crystalline films with different concentration of nitrogen vacancies (V N) were obtained, which were confirmed by the X-ray diffraction spectroscopy and Raman measurements. The magnetic behaviors of these films were also obtained to investigate the effects of nitrogen vacancies. It indicates that V N play a significant role in the origin of ferromagnetism. The stronger room-temperature ferromagnetism is given with the higher V N concentration when it is not beyond a critical concentration. Moreover, from our M(T) curves and Raman analysis, the films present high resistivity. The magnetism of films with high resistivity varies with concentration of nitrogen vacancies, which can be explained by the bound magnetic polarons (BMP) theory.  相似文献   

3.
Growth of TiN films at low temperature   总被引:1,自引:0,他引:1  
L.I. Wei 《Applied Surface Science》2007,253(17):7019-7023
Thermodynamic analysis on growth of TiN films was given. The driving force for deposition of TiN is dependent on original Ti(g)/N(g) ratio and original partial pressure of N(g). TiN films were deposited by ion beam assisted electron beam evaporation system under suitable nitrogen gas flow rate at 523 K while the density of plasma varied with diverse discharge pressure had been investigated by the Langmuir probe. TiN films were characterized by means of Fourier transform infrared absorption spectrum (FTIR), X-ray diffraction (XRD) and observed by means of atom force microscopy (AFM). The results of these measurements indicated preferential TiN(1 1 1) films were deposited on substrate of Si(1 0 0) and glass by ion beam assisted electron beam evaporation system at low temperature, and it was possible for the deposition of TiN films with a preferential orientation or more orientations if the nitrogen gas flow rate increased enough. Sand Box was used to characterize the fractal dimension of surface of TiN films. The results showed the fractal dimension was a little more than 1.7, which accorded with the model of diffusion limited aggregation (DLA), and the fractal dimension of TiN films increased with increase of the temperature of deposition.  相似文献   

4.
High-quality (good crystallinity and stoichiometry) titanium nitride (TiN) thin films were grown on Si(100) substrates by pulsed laser deposition (PLD) using a high-purity titanium target (99.99%) and nitrogen radical beam. The crystallinity, chemical composition, and depth profiles of the grown films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectroscopy (RBS), respectively. The XRD pattern indicated that the preferred growth of TiN(200) with an orientation parallel to the Si(100) direction was obtained and the nitrogen radical drastically improved crystallinity compared with that grown in ambient nitrogen gas. RBS spectra indicated that the combination of PLD and the nitrogen radical beam suppressed silicidation at the interface between the Si substrate and TiN thin film during growth. The XPS analysis revealed that this method achieved the synthesis of stoichiometric TiN films.  相似文献   

5.
硼/氮原子共注入金刚石的原子级研究   总被引:1,自引:0,他引:1       下载免费PDF全文
李荣斌 《物理学报》2007,56(1):395-399
利用Tersoff势和分子动力学方法研究了室温下500 eV的能量粒子硼(4个)和氮(8个)共注入金刚石晶体中晶体结构的变化特征和缺陷分布特征.结果表明:粒子注入金刚石后产生的空位比间隙原子更靠近晶体的近表层分布;间隙原子主要以四面体间隙(T形)和哑铃状分裂间隙的形式存在于晶体中,T形间隙结构更容易存在,并且大部分间隙原子富集在空位的周围;注入金刚石中的硼原子和氮原子有78%左右处于替代位置,硼、氮原子之间的键长比完整金刚石结构的键长短13%,硼氮原子成键有利于减少金刚石晶格的畸变程度.  相似文献   

6.
In this study, we use first principles multiple scattering calculations on atomic clusters to show how the carbon and nitrogen K-edge fine structures are modified in the vicinity of structural defects in TiN and TiC. Changes in the electron energy loss spectra are due to changes in the atomic structure of the first atomic shells around the absorbing atom. Two different kinds of defects, which both modify the structure of these atomic shells, are investigated here. In a first part, we describe a method which correctly takes into account the statistical spatial distribution of nitrogen vacancies in a TiN cluster. We study the influence of vacancy concentration on the shape of the nitrogen K-edge spectra and we find that vacancies mainly affect the height of the second peak of the spectra. This peak decreases when the number of vacancies in the second nitrogen shell increases. In a second part, we study the carbon K-edge spectrum modification near stacking faults in TiC. Two different stacking faults are studied. These two-dimensional defects are responsible for changes in the position of the carbon as well as titanium atoms of the atomic shells centered on the absorbing carbon atom. The shape of the spectra is strongly modified near the stacking faults and several peaks are affected by these modifications. We show that these fine structure modifications only concern the very first carbon atomic layers near the two-dimensional defects.  相似文献   

7.
TiN thin films were grown on stainless steel substrates by using the reactive radio-frequency magnetron-sputtering technique at relatively low temperature (200°C) using Ti and N2. The deposition rate of the TiN film increased linearly with increasing applied radio-frequency power, and it decreased with increasing partial-pressure ratio of the N2 gas to the Ar gas. Scanning electron microscopy (SEM) showed that the surfaces of the TiN films had very smooth morphologies. The TiN thin film had good stoichiometry for a partial-pressure ratio of 0.05. The stoichiometry of the TiN films and the interface qualities of the TiN/stainless steel heterostructures were investigated by Auger electron spectroscopy (AES) measurements. Auger depth profiles indicated that the compositions of the as-grown films consisted of titanium and nitrogen uniformly distributed throughout the films and that the films exhibited smooth interfaces. The interface quality of the TiN films to the stainless steel substrates were improved by annealing. These results indicate that annealed TiN thin films grown on stainless steel substrates hold promise for potential applications in advanced ceramic devices.  相似文献   

8.
利用磁控溅射在重掺硼硅(p+-Si)衬底上分别沉积TiO2薄膜和掺硼的TiO2(Ti O2∶B)薄膜,并经过氧气氛下600℃热处理,由此形成相应的TiO2/p+-Si和TiO2∶B/p+-Si异质结。与Ti O2/p+-Si异质结器件相比,TiO2∶B/p+-Si异质结器件的电致发光有明显的增强。分析认为:TiO2∶B薄膜经过热处理后,B原子进入TiO2晶格的间隙位,引入了额外的氧空位,而氧空位是TiO2/p+-Si异质结器件电致发光的发光中心,所以上述由B掺杂引起的氧空位浓度的增加是TiO2∶B/p+-Si异质结器件电致发光增强的原因。  相似文献   

9.
Ferromagnetic full Heusler alloys containing Co are amongst the most studied half‐metallic systems. Several studies recently have been concentrated on the effect of defects and impurities. We focus in this Letter on the case of vacancies in these alloys. We show that the occurrence of vacancies at the sites occupied by Co atoms can destroy half‐metallicity and alters the Slater–Pauling rule. Such defects are likely to occur since they result to the C1b lattice structure of the semi‐Heusler alloys. Contrary, the appearance of vacancies at the other sites keeps the half‐metallic character of the parent alloys. Thus for realistic devices it is important to prevent the appearance of vacancies during the growth of thin films. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

10.
李荣斌  于忠海 《物理学报》2007,56(6):3360-3365
借助于Tersoff势函数和分子动力学模拟技术研究了室温下500eV的能量粒子硼(4个)和氮(8个)共掺入金刚石晶体中所引起的损伤区域内晶体微细观结构的变化特征以及后续加热退火晶体结构的演变特征.结果表明:随着掺入原子数目的增加,受影响的区域范围渐渐增大,12个粒子全部注入金刚石晶体后局部影响区域的半径达0.68nm,损伤区域中心的三配位原子数增加而四配位数原子数量减少.加热退火过程中损伤中心区域的原子发生扩散,部分原子的扩散距离达到4个晶格间距.加热退火使损伤区域中心原子间的平均键长趋于金刚石结构的键长.退火后薄膜中注入的杂质原子向表面扩散引起应力分布产生变化,杂质原子经过一系列的扩散过程能够到达空位的位置,减少薄膜中空位数量,减小晶格畸变程度,原子向表面扩散引起应力产生重新分布,薄膜中应力峰值的峰位向薄膜表面发生移动,局部应力集中程度降低.通过不同退火温度的比较发现低温下退火(800℃)更有利于空位的运动和晶格损伤的恢复从而提高晶格质量. 关键词: 金刚石共掺杂 分子动力学 退火  相似文献   

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