共查询到19条相似文献,搜索用时 15 毫秒
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以有限元法为理论分析手段模拟分析了温度梯度法合成宝石级金刚石大单晶的腔体温度场,实现了对宝石级金刚石的合成腔体内各位置温度同时测量.模拟结果表明:在宝石级金刚石合成过程中,其温度分布呈不均匀分布.腔体内高温区分布在样品(碳源+触媒)边缘,低温区分布在籽晶附近.样品腔内热量的传递方式和样品腔内的碳源输运方式相同,均由碳源的两侧向籽晶附近传输.籽晶附近轴向温度梯度大于径向温度梯度,导致单位时间内其轴向生长尺寸大于径向生长尺寸.宝石级金刚石腔体温度场分析的理论模型的成功构建,为新型宝石级金刚石腔体的研制提供了良好的设计基础,对促进优质宝石级金刚石的生长技术具有指导意义. 相似文献
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辉光等离子体辅助化学气相沉积低温合成金刚石薄膜的研究 总被引:5,自引:0,他引:5
采用辉光放电等离子体增强化学气相沉积 (GP CVD)技术在低温条件下合成了高品质的亚微米金刚石薄膜 ,并通过对合成过程的实时发射光谱诊断确定了 [CH4 H2 ]系统参与金刚石合成反应的主要荷能粒子。对合成过程的研究表明 :采用这种技术能使电子增强热丝化学气相沉积 (EACVD)合成高品质金刚石薄膜的温度从 85 0℃降至 (340± 5 )℃ ;薄膜低温合成中的主要荷能粒子为CH3 、CH ,CH+ 、H 等 ,其中过饱和原子氢保证了高品质金刚石薄膜的合成 ;根据光诊断和探针测量的结果推断近表面辉光放电可在基片表面形成电偶极层 ,该偶极层是进行超常态反应的必要环境 ,并在低温合成中起重要作用 相似文献
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采用多能场复合微细电沉积加工技术,制备了微观结构渐变的多彩结构色磁性Al2O3-Co复合薄膜.在沉积电场和与之垂直的偏转电场作用下,复合薄膜的微观结构、光学特性和磁性沿偏转电场方向呈现渐变特征.通过建立微观结构等效模型,理论分析了复合薄膜微观结构变化机理.通过软件仿真定量分析了沿偏转电场方向Co离子沉积电流密度分布规律,仿真结果与理论研究和实验结果相吻合.研究发现,采用多能场复合的微细电沉积加工技术可以从微观角度调控复合薄膜微区结构,实现对薄膜微区磁学和光学特性的精细调控. 相似文献
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类金刚石(DLC)薄膜在红外区有很高的透过率,但激光损伤阈值低,严重限制了其应用领域。采用直接在DLC薄膜上沉积Ti电极,基于激光损伤阈值(LIDT)测试平台,用1-on-1零几率损伤法,研究了在不同偏置电场下DLC薄膜损伤阈值及损伤形貌的变化。发现电场强度从0增加到700V/cm,损伤阈值明显增大;进一步增大偏置电场,损伤阈值相对不变。分析认为偏置电场改变了激光辐照DLC薄膜区域的光生载流子漂移速度,减小了DLC薄膜的局部热累积,减缓了薄膜的石墨化进程,提高了DLC薄膜的抗激光损伤阈值。 相似文献
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利用热丝化学气相沉积法研究了氮气浓度对金刚石薄膜成核和生长的影响.实验发现氮气的 加入对金刚石成核密度影响不大,但促进了已形成的金刚石核的长大.适量的氮气不仅使金 刚石生长速率得到很大的提高,而且稳定了金刚石薄膜(100)面的生长,使金刚石薄膜具有 更好的(100)织构.利用原位光发射谱对衬底附近的化学基团进行了研究.研究表明,氮气的 引入使得金刚石生长的气相化学和表面化学性质发生了很大变化.含氮基团的萃取作用提高 了金刚石表面氢原子的脱附速率,从而提高了金刚石膜的生长速率.而含氮基团的选择吸附 使金刚石
关键词:
氮气
金刚石薄膜
织构
原位光发射谱 相似文献
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《光学学报》2016,(7)
采用微波等离子体气相沉积(MPCVD)在商用3mm×3mm×1 mm高温高压合成(HPHT)Ib型(100)金刚石衬底上同质外延生长B掺杂金刚石薄膜,并在此材料的基础上用磁控溅射和电子束蒸镀技术制备了不同结构参数金刚石肖特基势垒二极管。测试结果表明:所生长的金刚石薄膜表面非常平整,可以看到比较明显的原子台阶;所制备的器件具有明显的整流特性,肖特基电极直径100μm,肖特基电极和欧姆电极间距10μm,外加电压-15V,300K时测得器件正向导通电阻20Ω,反向饱和电流近似为10-6 A,反向击穿电压大约103.5V;电极间距越大,反向击穿电压越高,器件正向电流越小。 相似文献
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. Mekinis R. Gudaitis V. Kopustinskas S. Tamulevi
ius 《Applied Surface Science》2008,254(16):5252-5256
In present study diamond like carbon (DLC) films were deposited by closed drift ion source from the acetylene gas. The electrical and piezoresistive properties of ion beam synthesized DLC films were investigated. Diode-like current–voltage characteristics were observed both for DLC/nSi and DLC/pSi heterostructures. This fact was explained by high density of the irradiation-induced defects at the DLC/Si interface. Ohmic conductivity was observed for DLC/nSi heterostructure and metal/DLC/metal structure at low electric fields. At higher electric fields forward current transport was explained by Schottky emission and Poole–Frenkel emission for the DLC/nSi heterostructures and by Schottky emission and/or space charge limited currents for the DLC/pSi heterostructures. Strong dependence of the diamond like carbon film resistivity on temperature has been observed. Variable range hopping current transport mechanism at low electric field was revealed. Diamond like carbon piezoresistive elements with a gauge factor in 12–19 range were fabricated. 相似文献
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The influence of electric fields on the low temperature oxidation of individual nanoscale tungsten wires was investigated. In the experiments at room temperature, the nanowires were biased as anode opposite to a macroscopic cathode and H2O-vapor with a pressure of 10?7–101 mbar was provided as oxygen source. Under the influence of an electric field, a dramatic change of the oxidation behavior is observed with the formation of several 10 nm thick oxide layers for electric fields exceeding a threshold. The chemical composition of the layers formed is determined with laser-assisted atom probe tomography to be slightly understoichiometric WO3. After an initial period of fast growth, the oxidation rate later rapidly decreases to immeasurable low values. Evaluation of the electric field distribution in the vicinity of the sample by the finite element method reveals that oxide formation only proceeds if a critical field in the range of 0.7–5.0 V/nm, depending on the H2O-pressure, is present. This critical field is attributed to a field-activated reaction of H2O at the oxide–vapor interface. Besides for tungsten, field-induced oxidation is also observed for aluminum and p-doped silicon and thus apparently is a widely material independent phenomenon. 相似文献
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Zinc oxide (ZnO) nanorods grown on chemical vapor deposited diamond films by thermal vapor transport method have been investigated. In the initial growth status, the semi-spherical ZnO nuclei were preferably deposited near the growth steps on the terraces and the boundaries of diamond grains. With increasing the growth time, the [0 0 0 1] orientated ZnO nanorods appeared and further covered the whole diamond film. It is found that the size of diamond grains would determine the diameter of ZnO nanorods. The electron field emission properties of the ZnO nanorods/diamond system have been significantly improved with respect to pure diamond film. The feature of the ZnO nanorods grown on diamond films played an important role in further enhancing the electron field emission performances. 相似文献
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采用蒙特卡罗方法,对以CH4/H2为源料气体的电子助进化学气相沉积(EACVD)金刚石中的氢原子(Hα,Hβ和Hγ)、碳原子C(2p3s→2p2: λ=165.7 nm)以及CH(A2Δ→X2Π: λ=420~440 nm)的发射过程进行了模拟,研究了衬底温度对各发射谱线以及金刚石膜合成的影响。结果得知,各谱线强度随衬底温度的变化幅度很小,且在衬底表面附近的谱线强度随衬底温度的变化幅度相对于远离衬底的反应区域较大,这表明衬底温度的变化基本上不改变远离衬底的反应区域中反应基团成分,而只对衬底表面附近的反应过程有影响。由此得知,衬底温度对薄膜质量的决定性主要是由于衬底温度改变了衬底表面化学反应动力学过程和表面附近的反应基团的缘故,而不是衬底温度对反应空间中气相成分的影响。 相似文献
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J. S. Wang Y. Cheng Q. J. Huang X. J. Liu S. Y. Zhang 《The European physical journal. Special topics》2008,153(1):155-158
The three-dimensional (3D) temperature field of
laser-induced transient thermal grating (TTG) for two-layered structures
such as diamond/substrate is obtained by the finite element method (FEM).
The numerical results indicate that the thickness of the diamond film has a
significant influence on the temperature field. On the other hand, we
further find that variation of the substrate significantly affects on the
temperature distribution in the diamond film, which has been ascribed to the
various thermal conductivities of the substrates. 相似文献
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利用非对称磁镜场电子回旋共振等离子体产生的氧回旋离子束刻蚀了化学气相沉积金刚石膜,研究了工作气压和磁电加热电压对金刚石样品附近的离子温度和密度的影响,并分析了金刚石膜的刻蚀和机械抛光效果。结果表明:当工作气压为0.03 Pa,磁电加热电压为200 V时,离子温度和密度最大,分别为7.38 eV和 23.81010 cm-3 。在此优化条件下刻蚀金刚石膜4 h后,其表面粗糙度由刻蚀前的3.525 m降为2.512 m,机械抛光15 min后,表面粗糙度降低为0.517 m,即金刚石膜经离子束刻蚀后可显著提高机械抛光效率。 相似文献
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The behaviour of electrons in CH_{4}/H_{2} gas mixture in electron-assisted chemical vapour deposition of diamond is investigated using Monte Carlo simulation. The electron drift velocity in gas mixture is obtained over a wide range of E/P (the ratio of the electric field to gas pressure) from 1500 to 300000 (V/m kPa^{-1}). The electron energy distribution and average energy under different gas pressure (0.1-20kPa) and CH_{4} concentration (0.5%-10.0%) are calculated. Their effects on the diamond growth are also discussed. It is believed that these results will be helpful to the selection of optimum experimental conditions for high quality diamond film deposition. 相似文献