title: Optical properties and sub-bandgap formation of nano-crystalline Si quantum dots embedded ZnO thin film.
abstract: In this study, we fabricate ZnO thin films with nano-crystalline Si (nc-Si) quantum dots (QDs) using a ZnO/Si multilayer deposition structure and a post-annealing process, and the formation of high crystallinity of Si QDs embedded in the crystalline ZnO matrix is demonstrated. For optical properties, the essential features of ZnO material, high transmission in long-wavelength and high absorption in short-wavelength ranges, are preserved. We observe significantly enhanced light absorption and an unusual photoluminescence emission peak contributed from the nc-Si QDs in the middle-wavelength range. In addition, we confirm the formation of optical sub-bandgap and the obtained value is quite close to the unusual PL emission peak. We show that meaningful sub-bandgap can form in ZnO thin film by embedding nc-Si QDs while maintaining the advantageous properties of ZnO matrix. This newly developed composite material, nc-Si QD embedded ZnO thin films, can be useful for various electro-optical applications.
authors.affiliation: Department of Photonics & Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, Taiwan.
authors.forename: Kuang-Yang
authors.initials: KY
authors.lastname: Kuo
authors.forename: Shu-Wei
authors.initials: SW
authors.lastname: Hsu
authors.forename: Pin-Ruei
authors.initials: PR
authors.lastname: Huang
authors.forename: Wen-Ling
authors.initials: WL
authors.lastname: Chuang
authors.forename: Chuan-Cheng
authors.initials: CC
authors.lastname: Liu
authors.forename: Po-Tsung
authors.initials: PT
authors.lastname: Lee
mesh_terms: D000042:Absorption; D003460:Crystallization; D004563:Electrochemistry / Q000379:methods; D008422:Materials Testing; D008567:Membranes, Artificial; D018625:Microscopy, Atomic Force / Q000379:methods; D036103:Nanotechnology / Q000379:methods*; D055095:Optics and Photonics / Q000379:methods; D045663:Quantum Dots; D012825:Silicon / Q000737:chemistry*; D013053:Spectrophotometry / Q000379:methods; D013059:Spectrum Analysis, Raman / Q000379:methods; D013499:Surface Properties; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D008567:Membranes, Artificial; D015034:Zinc Oxide; D012825:Silicon