Quantum confinement effect in multilayer structure of alternate CdSe and SiO_x insulator matrix thinfilms

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• 作者：M. Melvin David Kumar ; ^{melvin@karunya.edu} ; Suganthi Devadason
• 关键词：CdSe/SiOx ; Multilayer structure ; Quantum confinement ; Thermal evaporation
• 刊名：Superlattices and Microstructures
• 出版年：2013
• 出版时间：June, 2013
• 年：2013
• 卷：58
• 期：Complete
• 页码：154-164
• 全文大小：887 K

文摘

Multilayer (ML) structure of layer-by-layer deposited CdSe/SiO_x thin films and their monolayers were prepared using sequential thermal evaporation technique. X-ray diffraction study confirmed the (002) plane of CdSe with wurtzite structure. It is noticed that the microstrain, developed in ML thin films, increased with decreasing particle size. Experimentally measured band gap energies confirmed the splitting of valence band energy levels which rise due to hole confinement in CdSe. Crystallite sizes (5-7 nm) were calculated using the effective mass approximation model (i.e., Brus model) which shows that the diameter of crystallites was smaller than the Bohr exciton diameter (11.2 nm) of CdSe. The main band in the emission spectra of ML samples gradually shifted to longer wavelength side when particle size was increased from 5 to 7 nm. This is characteristic of quantum size effect. It is inferred that disorderliness in CdSe/SiO_x ML thin films would increase when the thickness of CdSe sublayer is greater than that of SiO_x matrix layer.