Department of Chemistry, Centre for Materials Science and Nanotechnology, University of Oslo, Sem Sælandsvei 26, 0371 Oslo, Norway.
Dalton Trans. 2013 Aug 14;42(30):10778-85. doi: 10.1039/c3dt51270c. Epub 2013 Jun 18.
Ln2O3 thin films with optically active f-electrons (Ln = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb) have been grown on Si(100) and soda lime glass substrates by atomic layer deposition (ALD) using Ln(thd)3 (Hthd = 2,2,6,6-tetramethyl-3,5-heptanedione) and ozone as precursors. The temperature range for depositions was 200-400 °C. Growth rates were measured by spectroscopic ellipsometry and a region with a constant growth rate (ALD window) was found for Ln = Ho and Tm. All the compounds are grown as amorphous films at low temperatures, whereas crystalline films (cubic C-Ln2O3) are obtained above a certain temperature ranging from 300 to 250 °C for Nd2O3 to Yb2O3, respectively. AFM studies show that the films were smooth (rms < 1 nm) except for depositions at the highest temperatures. The refractive index was measured by spectroscopic ellipsometry and was found to depend on the deposition temperature. Optical absorption measurements show that the absorption from the f-f transitions depends strongly on the crystallinity of the material. The clear correlation between the degree of crystallinity, optical absorptions and refractive indices is discussed.
具有光学活性 f 电子的 Ln2O3 薄膜（Ln = Pr、Nd、Sm、Eu、Tb、Dy、Ho、Er、Tm、Yb）已通过原子层沉积（ALD）在 Si（100）和钠钙玻璃衬底上生长，使用 Ln(thd)3（Hthd = 2,2,6,6-四甲基-3,5-庚二酮）和臭氧作为前驱体。沉积温度范围为 200-400°C。通过光谱椭圆测量法测量生长速率，并为 Ln = Ho 和 Tm 找到了一个具有恒定生长速率的区域（ALD 窗口）。所有化合物在低温下均以非晶态薄膜生长，而在一定温度以上则获得晶态薄膜（立方 C-Ln2O3），对于 Nd2O3 至 Yb2O3，分别为 300 至 250°C。原子力显微镜研究表明，除了在最高温度下沉积的情况外，薄膜均很光滑（均方根 < 1nm）。通过光谱椭圆测量法测量折射率，发现它取决于沉积温度。光学吸收测量表明，f-f 跃迁的吸收强烈依赖于材料的结晶度。讨论了结晶度、光学吸收率和折射率之间的明显相关性。
