Atomic-layer-deposited silver and dielectric nanostructures for plasmonic enhancement of Raman scattering from nanoscale ultrathin films

作者：Ko Chung Ting^*; Yang Po Shuan; Han Yin Yi; Wang Wei Cheng; Huang Jhih Jie; Lee Yen Hui; Tsai Yi Jen; Shieh Jay; Chen Miin Jang

来源：Nanotechnology, 2015, 26(26): 265702.

DOI：10.1088/0957-4484/26/26/265702

• atomic layer deposition
• surface enhanced Raman scattering
• plasmonics
• high-K gate dielectrics
• silver

Plasmonic silver nanostructures and a precise ZnO cover layer prepared by capacitively coupled plasma atomic layer deposition (ALD) were exploited to enhance the Raman scattering from nanoscale ultrathin films on a Si substrate. The plasmonic activity was supported by a nanostructured Ag (nano-Ag) layer, and a ZnO cover layer was introduced upon the nano-Ag layer to spectrally tailor the localized surface plasmon resonance to coincide with the laser excitation wavelength. Because of the optimized dielectric environment provided by the precise growth of ZnO cover layer using ALD, the intensity of Raman scattering from nanoscale ultrathin films was significantly enhanced by an additional order of magnitude, leading to the observation of the monoclinic and tetragonal phases in the nanoscale ZrO2 high-K gate dielectric as thin as similar to 6nm on Si substrate. The excellent agreement between the finite-difference time-domain simulation and experimental measurement further confirms the so-called vertical bar E-(sic)vertical bar(4) dependence of the surface-enhanced Raman scattering. This technique of plasmonic enhancement of Raman spectroscopy, assisted by the nano-Ag layer and optimized dielectric environment prepared by ALD, can be applied to characterize the structures of ultrathin films in a variety of nanoscale materials and devices, even on a Si substrate with overwhelming Raman background.

• 出版日期2015-7-3