Structural tunability and origin of two-level systems in amorphous silicon
Structural tunability and origin of two-level systems in amorphous silicon
复制标题
非晶硅中两能级系统的结构可调性和起源
DOI：
10.1103/physrevmaterials.6.045604
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发表时间：
2022
影响因子：
3.4
通讯作者：
Hellman, F.
中科院分区：
文献类型：
--
作者：
Jacks, H. C.;Molina-Ruiz, M.;Weber, M. H.;Maldonis, J. J.;Voyles, P. M.;Abernathy, M. R.;Metcalf, T. H.;Liu, X.;Hellman, F.
用电子束蒸发法制备的非晶硅薄膜在较高的厚度、较高的生长温度和较慢的沉积速率下具有系统地和实质上更大的原子密度，当在425 ℃和1 μ m/s下生长厚度大于300 nm的薄膜时达到晶体Si的密度。光谱技术的组合提供了深入了解原子无序，局部应变，悬挂键，和纳米空隙。电子衍射表明，在所有的生长温度下的非晶硅的短程顺序是相似的，但波动电子显微镜显示，高于室温下生长的薄膜显示出一种形式的中程顺序以前没有观察到的非晶硅。从拉曼光谱得到的原子无序和局部应变随生长温度的增加而减少，并显示出对厚度的非单调依赖性。悬挂键密度随生长温度的升高而降低，并且仅轻微地依赖于厚度。正电子湮没多普勒展宽光谱和电子能量损失光谱表明，纳米空隙，而不是网络内的密度变化，是负责减少原子密度。比热和机械损耗的测量，量化的隧道两级系统的密度，结合结构数据，表明在非晶硅薄膜中的两级系统与nanovoids和它们的周围，这是在本质上松散的结合区域的原子较少约束。
Amorphous silicon films prepared by electron-beam evaporation have systematically and substantially greater atomic density for higher thickness, higher growth temperature, and slower deposition rate, reaching the density of crystalline Si when films of thickness greater than300 nm are grown at 425C and at1 Å/s. A combination of spectroscopic techniques provide insight into atomic disorder, local strains, dangling bonds, and nanovoids. Electron diffraction shows that the short-range order of the amorphous silicon is similar at all growth temperatures, but fluctuation electron microscopy shows that films grown above room temperature show a form of medium-range order not previously observed in amorphous silicon. Atomic disorder and local strain obtained from Raman spectroscopy are reduced with increasing growth temperature and show a nonmonotonic dependence on thickness. Dangling bond density decreases with increasing growth temperature and is only mildly dependent on thickness. Positron annihilation Doppler broadening spectroscopy and electron energy loss spectroscopy show that nanovoids, and not density variations within the network, are responsible for reduced atomic density. Specific heat and mechanical loss measurements, which quantify the density of tunneling two-level systems, in combination with the structural data, suggest that two-level systems in amorphous silicon films are associated with nanovoids and their surroundings, which are in essence loosely bonded regions where atoms are less constrained.
DOI：
--
发表时间：
2015
期刊：
影响因子：
--
作者：
D. Queen;Xiao Liu;Julie Karel;H. Jacks;T. Metcalf;F. Hellman
通讯作者：
F. Hellman
高密度电感耦合等离子体蚀刻反应器中蚀刻引起的损伤
DOI：
--
发表时间：
1996
期刊：
影响因子：
--
作者：
D. Misra;W. Zhong;R. Bartynski;V. Patel;B. Singh
通讯作者：
B. Singh
DOI：
--
发表时间：
1977
期刊：
影响因子：
--
作者：
D. Beeman;R. Alben
通讯作者：
R. Alben