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arXiv 1104.3518cond-mat.mtrl-sciastro-ph.IM
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NbSi薄膜的原子层沉积及其超导性能

Atomic layer deposition and superconducting properties of NbSi films

Thomas Proslier, Jeffrey A. Klug, Jeffrey W. Elam, Helmut Claus, Nicholas G. Becker, Michael Pellin

摘要:

以NbF 5和Si 2 H6为前驱体,采用原子层沉积法制备了化学计量比为1:1的硅化铌(NbSi)薄膜。用石英晶体微天平(QCM)和四极质谱仪(QMS)研究了200 ℃下的生长机理。该研究显示了自限性反应,生长速率为4.5 μ g/周期。发现NbSi仅生长在使用卤化前体制备的无氧化物膜上。在150- 400摄氏度的沉积温度范围内研究了薄膜的电子性质、生长速率、化学组成和结构。在所有温度下,薄膜均为化学计量比为1:1的NbSi薄膜,无氟杂质,密度为6.65g/cm ~ 3的非晶态薄膜,厚度大于35 nm的薄膜在300 K时电阻率ρ=150 μΩ·cm。在150- 275 ℃之间的沉积温度下,生长速率几乎是恒定的,但在300 ℃以上则会增加,这表明非自限性生长的开始。在1.2K温度下测量了薄膜的电子性质,发现在Tc=3.1K时发生了超导转变。据我们所知,以前从未用任何技术生长过化学计量比为1:1的超导硅化铌薄膜。

英文摘要:

Atomic layer deposition was used to synthesize niobium silicide (NbSi) films with a 1:1 stoichiometry, using NbF5 and Si2H6 as precursors. The growth mechanism at 200oC was examined by in-situ quartz crystal microbalance (QCM) and quadrupole mass spectrometer (QMS). This study revealed a self-limiting reaction with a growth rate of 4.5 Å/cycle. NbSi was found to grow only on oxide-free films prepared using halogenated precursors. The electronic properties, growth rate, chemical composition, and structure of the films were studied over the deposition temperature range 150-400oC. For all temperatures, the films are found to be stoichiometric NbSi (1:1) with no detectable fluorine impurities, amorphous with a density of 6.65g/cm3, and metallic with a resistivity ρ=150 μΩ.cm at 300K for films thicker than 35 nm. The growth rate was nearly constant for deposition temperatures between 150-275oC, but increases above 300oC suggesting the onset of non-self limiting growth. The electronic properties of the films were measured down to 1.2K and revealed a superconducting transition at Tc=3.1K. To our knowledge, a superconducting niobium silicide film with a 1:1 stoichiometry has never been grown before by any technique.

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