title: Orientation-controlled growth and optical properties of diverse Ag nanoparticles on Si(100) and Si(111) wafers.
abstract: Well-controlled growth of Ag nanoparticles (NPs) on Si substrates is important for next generation Si-based optoelectronic devices, but only randomly oriented Ag NPs have been previously reported. In this work, well-oriented Ag NPs with regular shapes are pseudomorphically grown on Si(100) and Si(111) substrates with crystallographic relationships of {100} mathematical left angle bracket 010 mathematical right angle bracket Ag ∥ {100} mathematical left angle bracket 010 mathematical right angle bracket Si and {111} mathematical left angle bracket 110 mathematical right angle bracket Ag ∥ {111} mathematical left angle bracket 110 mathematical right angle bracket Si, respectively. From a cross-sectional image, the Ag NPs on Si(100) substrates penetrate into Si and generate an inverted pyramid-like structure terminated by {111} planes embedded in Si substrates. In contrast, the Ag NPs on Si(111) substrates show flat morphology with the top plane terminated by Ag {111}. The Si underneath Ag NPs was not penetrated by Ag and a SiO(2) layer was formed between Ag and Si. Photoluminescence spectra of the Ag NPs show ultraviolet emissions centered in the 340-343 nm range. The mathematical left angle bracket 111 mathematical right angle bracket-oriented Ag particles show stronger emissions with an extra peak at 343 nm compared with mathematical left angle bracket 100 mathematical right angle bracket-oriented Ag NPs. Raman spectra show that the mathematical left angle bracket 100 mathematical right angle bracket - and mathematical left angle bracket 111 mathematical right angle bracket-oriented Ag NPs can enhance the peak intensity of Si(100) and Si(111) by 45.3% and 32.5%, respectively. The orientation-controlled Ag NPs with anisotropic optical properties are promising materials for Si-based optoelectronics.
authors.affiliation: Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan. rcwang@nuk.edu.tw
authors.forename: Ruey-Chi
authors.initials: RC
authors.lastname: Wang
authors.forename: Yu-Xian
authors.initials: YX
authors.lastname: Lin
authors.forename: Michael R S
authors.initials: MR
authors.lastname: Huang
authors.forename: Chien-Yang
authors.initials: CY
authors.lastname: Chao
mesh_terms: D000327:Adsorption; D003460:Crystallization / Q000379:methods*; D008027:Light; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000528:radiation effects; D008968:Molecular Conformation / Q000528:radiation effects; D010316:Particle Size; D012031:Refractometry; D012542:Scattering, Radiation; D012825:Silicon / Q000737:chemistry*; D012834:Silver / Q000737:chemistry* / Q000528:radiation effects; D013499:Surface Properties / Q000528:radiation effects
chemical_list: D012834:Silver; D012825:Silicon