Ciesielski Arkadiusz, Skowronski Lukasz, Trzcinski Marek, Górecka Ewa, Pacuski Wojciech, Szoplik Tomasz
University of Warsaw, Faculty of Physics, Pasteura 5 Str., 02-093 Warsaw, Poland.
UTP University of Science and Technology, Institute of Mathematics and Physics, Kaliskiego 7 Str., 85-796 Bydgoszcz, Poland.
Beilstein J Nanotechnol. 2019 Jan 21;10:238-246. doi: 10.3762/bjnano.10.22. eCollection 2019.
Noble metal nanolayers on flat substrates are often deposited with the use of semiconductor interlayers, which may strongly interact with the noble metal overlayer. We investigated the crystallinity, atomic concentration profile and optical parameters of ≈35 nm-thick silver and gold layers deposited on glass substrates with 2 nm-thick tellurium or selenium interlayers. Our study, based on X-ray reflectometry (XRR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and ellipsometric measurements, showed that using either of these interlayers introduces strain in nanocrystals of both plasmonic films. This, in turn, influences the migration of Se and Te into the metal layers. Selenium atoms migrate both in the silver and gold nanolayers, while tellurium atoms migrate only in silver. The Te concentration curve clearly suggests that this migration is an effect of the segregation of Te atoms in the silver structure. The differences in crystallinity, as well as the migration process, strongly influence the optical parameters of Ag and Au. In the permittivity of Ag deposited on either Te or Se, additional plasmonic bands originating from grain boundary segregation or diffusion occur, while for the Au layer, such resonances were not pronounced. In the permittivity of both materials, the intensity of the interband transition peaks is strongly altered, possibly due to the nano-alloy formation, but more likely due to the microstrain on metal grains.
平面衬底上的贵金属纳米层通常借助半导体中间层进行沉积，而半导体中间层可能会与贵金属覆盖层发生强烈相互作用。我们研究了沉积在具有2纳米厚碲或硒中间层的玻璃衬底上的约35纳米厚银层和金层的结晶度、原子浓度分布以及光学参数。我们基于X射线反射测量法（XRR）、X射线衍射（XRD）、X射线光电子能谱（XPS）和椭偏测量法的研究表明，使用这两种中间层中的任何一种都会在两种等离子体薄膜的纳米晶体中引入应变。这反过来又会影响硒和碲向金属层的迁移。硒原子在银纳米层和金纳米层中都会迁移，而碲原子仅在银中迁移。碲浓度曲线清楚地表明，这种迁移是碲原子在银结构中偏析的结果。结晶度以及迁移过程的差异强烈影响银和金的光学参数。在沉积在碲或硒上的银的介电常数中，会出现源自晶界偏析或扩散的额外等离子体带，而对于金层，这种共振并不明显。在这两种材料的介电常数中，带间跃迁峰的强度会发生强烈变化，这可能是由于纳米合金的形成，但更可能是由于金属晶粒上的微应变。
