报告题目：Silicon-Based Nanostructures for Photonics Applications
报告人：Dr. Peter Mascher，Department of Engineering Physics, McMaster University, Canada
报告时间：2010年5月20日上午8:00
报告地点：硅材料国家重点实验室会议室（半导体厂内3号楼）
报告摘要：Luminescent Si-based materials are of significant interest for photonic applications due to the potential of fabricating light emitting devices using current CMOS processing technologies. Such devices could find substantial use in solid state lighting (SSL) and for the development of optical interconnects. The possible application of luminescent Si-based materials for SSL has recently emerged as a particularly interesting area of research as it would offer substantial advantages in terms of cost and manufacturability. In order for Si-based materials to be used in SSL schemes it is necessary to have precise control of the emission from these materials. This is accomplished through the use of Ce, Tb, and Eu dopants in order to obtain precise blue, green, and red emissions, respectively. In this talk, I will discuss recent results obtained by my own research group in the design, fabrication, and characterization of Si nanostructures, with and without rare-earth (RE) doping. One method of producing luminescent Si is to reduce its size down to several nanometers, where quantum confinement effects lead to an enhancement of the radiative recombination efficiency. Luminescence from Si-nanoclusters (Si-ncs) is influenced by the size of the nanoclusters and the presence of surface states through which the recombination can occur. Much more narrowly defined emission wavelengths can be obtained by incorporating RE dopant ions into Si-nc embedded materials. Energy transfer may then occur between the Si-ncs and the RE ions, producing light emission characteristic of the ions. Ce, Tb, Eu and Er related emissions are observed from doped silicon oxides (oxygen-rich or silicon-rich) and nitrides, deposited by electron cyclotron resonance (ECR)-plasma enhanced chemical vapour deposition (PECVD) and/or inductively coupled (IC) PCVD and are found to be sensitive to the RE concentration, the presence of Si nanoclusters/crystals and annealing-induced structural evolution, such as the formation of secondary phases. Under optimized film compositions and annealing protocols, the light emission from these films is very bright and can be easily observed even under normal room lighting conditions.
We have studied the luminescence of rare earth (Ce, Tb, Eu) doped silicon oxides and nitrides through photoluminescence, X-ray excited optical luminescence (XEOL) and the analysis of X-ray absorption near edge structure (XANES) at the Si and O K-edges and the Si L3,2-edge. Through the analysis of the XANES and XEOL, details of the microscopic materials structure and its relation to the luminescence mechanisms could be determined. In particular, the chemical sensitivity of the XEOL process provides a site-specific method for the analysis of luminescence excitation processes. Our results indicate that oxygen-related energy states play an active role in the luminescence, with the brightest luminescence observed for samples where the silicon oxide submatrix was found to be O-rich. Finally, we will discuss the significance of the results in the context of developing electrically driven lighting cells suitable for SSL along with challenges in the development of white light emitters from rare earth doped Si-based materials.
Dr. Peter Mascher简介：
Peter Mascher obtained a PhD in Engineering Physics from the Graz University of Technology (TUG) in Austria and spent about four years as a post-doctoral fellow and research associate at the University of Winnipeg. He joined McMaster University in 1989 in a position initially funded by the Ontario Centre for Materials Research. He is a professional engineer and a professor in the Department of Engineering Physics, was Chair of the Department from 1995 to 2001, and currently serves as the Associate Dean (Research and External Relations) of the Faculty of Engineering. Dr. Mascher leads active research groups involved in the fabrication and characterization of thin films for optoelectronic applications, the development and application of silicon-based nanostructures, and the characterization of defects in solids by positron annihilation spectroscopy. His research work is funded by NSERC and several federal and provincial Centres of Excellence, as well as industry. He has graduated more than 30 PhD and Master’s students, has authored or co-authored close to 200 publications in refereed journals and conference proceedings, and has presented many invited lectures at international conferences and workshops.
Dr. Mascher is a member of McMaster’s Brockhouse Institute for Materials Research and the Centre for Emerging Device Technologies, as well as a number of international physics and materials research societies. He has organized or co-organized many international conferences, most recently a symposium on Nanoscale Luminescent Materials at the 217th Meeting of the Electrochemical Society. In 2001, he was appointed
(and re-appointed in 2006) as the inaugural holder of the William Sinclair Chair in Optoelectronics, a Chair that was established through a generous donation by William Sinclair, one of the co-founders of JDS-Fitel, now part of JDS-Uniphase. From 2003 to 2007 he served as the Program Director of the Ontario Photonics Consortium, and he currently is a member of the Board of Management of the Ontario Photonics Industry Network (OPIN) and the Centre of Photonics of Ontario Centres of Excellence (OCE).
