Defect studies in crystalline and amorphous materials Positron annihilation spectroscopy Deposition and characterization of silicon-based thin films for optoelectronic applications Aspects of plasma enhanced chemical vapour deposition Silicon photonics
In the Thin Film Laboratory, we are focusing on the Fabrication and Characterization of Nanostructures. There are several ongoing projects, among them
Silicon nanocrystals – a major focus of my group has been the exploration and description of the formation of silicon nanocrystals in silicon-rich oxides, nitrides, and oxy-nitrides, produced by post-deposition annealing of thin films grown by ECR-PECVD or inductively coupled plasma (ICP) CVD. Of particular interest are the effects of annealing in materials that are highly silicon rich, for applications in future nano-photonic devices. For such devices, nano-structured silicon shows substantial promise as quantum confinement effects make luminescence possible, which serves as the foundation of the rapidly emerging field of silicon photonics.
Rare-earth-doped structures – in collaboration with industrial partners, we have demonstrated very high, optically active concentrations of Er, Td, Ce, and Eu by using in-situ doping processes. Studies at the Canadian Light Source synchrotron facility (see below) have provided critical information on the luminescence mechanisms and the incorporation characteristics of the RE in various Si-based matrices. Most exciting form a practical perspective is the potential for tunability of the emission wavelength and/or the generation of white light.
Synchrotron studies – An important aspect of our work is the application of synchrotron-based techniques to the investigation of the luminescence mechanisms in rare earth doped, silicon-based structures. The results provide evidence that luminescence from these materials is correlated with the excitation of O-related energy states, and demonstrate that the composition and bonding structure of the silicon oxide host matrix play an active role in determining the luminescent properties, even though the microstructure of the films may vary from sample to sample. In order to optimize the luminescence from such materials it is, therefore, necessary to consider the local bonding environment of the RE-ions and specific details of electronic states associated with the host matrix.
Positrons are a unique probe of materials that provides information that is highly complementary to light, and other particle-based probes.
The McMaster Positron Laboratory is one of only three of its kind in Canada and very few in all of North America. Our positron-related research is concerned with the characterization of defect structures in materials utilized in the development and fabrication of electronic and photonic devices.
The McMaster Intense Positron Beam Facility (MIPBF), funded jointly by the Canada Foundation of Innovation (CFI) and the Ontario Ministry of Research and Innovation (MRI), will be one of only four such facilities worldwide and will support the engineering of new materials with properties and capabilities not found in nature. By using positrons to help probe and characterize new materials, we are aiming to accelerate the development of such materials, thereby giving Ontario’s advanced manufacturing industry an important competitive advantage. The MIPBF Surface Analysis System will reduce the measurement times of surfaces from many hours to a few minutes, ensuring the integrity of the surface being probed without recourse to in-situ cleaning. This will enable the determination of the growth kinetics of ultra-thin layers on metals, semiconductors and dielectrics, as well as the detailed study of nanostructures. The Positron Defect Probe will provide the ability to probe the nature of thin layers and interfaces, with depth resolution and with spectroscopic capacity. The Positron Storage and Interaction System will allow for the accumulation of cold-trapped positrons at a rate 100 times higher than at existing facilities, enabling experiments not possible with existing positron systems, including the production of positronic atoms for precision measurements, development of formation processes applicable to antihydrogen research, and production and studies of bound molecular states consisting of matter and antimatter.
Peter Mascher obtained a PhD in Engineering Physics in 1984 from the Graz University of Technology (TUG) in Austria and joined McMaster University in 1989. He is a professional engineer and a professor in the Department of Engineering Physics, and chaired the department from 1994 to 2000. From 2003 to 2014 he served as the Associate Dean (Research and External Relations) of the Faculty of Engineering, with responsibilities for coordinating major research initiatives and collaborations of the Faculty. Since February 2014 he is overseeing McMaster’s International Portfolio as Vice-Provost, International Affairs. He is a Fellow of the Canadian Academy of Engineering and the Electrochemical Society. In 2015, he was appointed as an Honorary Professor at Nanjing Tech University.
Dr. Mascher holds the William Sinclair Chair in Optoelectronics and 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 has been continuously funded for more than 30 years by the Natural Sciences and Engineering Research Council of Canada (NSERC), and has drawn funding from the Canada Foundation of Innovation (CFI), several federal and provincial Centres of Excellence, and industry, for a lifetime total surpassing $25M. Since 2010, he leads a collaborative initiative to transform the McMaster Nuclear Reactor into one of the world’s brightest positron sources for applied and fundamental research.
Dr. Mascher has supervised more than 75 graduate students and post-doctoral fellows, has authored or coauthored close to 250 publications in refereed journals and conference proceedings, and has presented many invited lectures at international conferences and workshops. He is a member of the Steering Committee of the Canadian Semiconductor Science and Technology Conference (CSSTC), the International Advisory Committee of the International Conference on Optical, Optoelectronic and Photonic Materials and Applications (ICOOPMA) and chair of the International Advisory Committee on Positron Annihilation. From 2003 to 2007 he served as the Program Director of the Ontario Photonics Consortium. Dr. Mascher served on the governing bodies of organizations as diverse as the University Network of Excellence in Nuclear Engineering (UNENE), the Steel Research Centre, the Green Auto Power Train Initiative, and the Network for the Engineering of Complex Software-Intensive Systems for Automotive Systems. He currently serves as a member of the Board of Directors of the Electrochemical Society, Chair of the International Committee of the Canadian Academy of Engineering and Vice-Chair of Nano Ontario.
Ph.D. (1984) – Institut für Kernphysik, Technische Universität Graz, Austria
Thesis: Investigations of the Behaviour of Positrons in Low-Melting Metals by the Lifetime Technique
M.Eng. (1980) – Technische Universität Graz, Austria
Thesis: Positron Lifetimes in Cadmium
Fellow of the Electrochemical Society (2016)
Honorary Professor, Nanjing Tech University, Nanjing, China (2015)
Fellow of the Canadian Academy of Engineering (2012)
William Sinclair Chair in Optoelectronics (since 2001)
Professional Engineer (P.Eng.) since 1993
Recent
Refereed Journal Publications (students and researchers under my direct supervision are listed in italics)
C.M. Naraine, J.W. Miller, H.C. Frankis, D.E. Hagan, P. Mascher, J.H. Schmid, P. Cheben, A.P. Knights and J.D.B. Bradley, “Subwavelength grating metamaterial waveguides functionalized with tellurium oxide cladding”, accepted for publication in Optics Express (June 2020)
Jeremy W. Miller, Michael Chesaux, Dino Deligiannis, Peter Mascher, Jonathan D. Bradley, “Low-loss GeO2 thin films deposited by ion-assisted AC Sputtering for waveguide applications”, accepted for publication in Thin Solid Films (May 2020)
Zahra Khatami and Peter Mascher, “Photoluminescence of silicon carbonitride thin films: The interdependence of post-deposition annealing and growth temperature”, J. Luminescence 214, 116563 (2019); doi: 10.1016/j.jlumin.2019.1165
Zahra Khatami, Peter J. Simpson, and Peter Mascher, “Process-dependent mechanical and optical properties of nanostructured silicon carbonitride thin films”, Nanotechnology 30, 314003 (14 pp) (2019); doi: 10.1088/1361-6528/ab180c
Bo Mi Lee, Jinwook Kim, Guem Jae Yun, Woo Young Kim, and Peter Mascher, “Study on Hybrid Blue Organic Light Emitting Diodes with Step Controlled Doping Profiles in Phosphorescent Emitting Layer”, Optical Materials 86, 498 – 504 (2018); doi: 10.1016/j.optmat.2018.09.039
G. Bosco, Z. Khatami, J. Wojcik, P. Mascher, and L. Tessler, “Excitation mechanism of Tb3+ in a-Si3N4:H under sub-gap excitation”, Journal of Luminescence 202, 327 – 331 (2018); doi: 10.1016/j.jlumin.2018.05.080
Z. Khatami, P. R. J. Wilson, J. Wojcik, and P. Mascher, “On the Origin of White Light Emission from Nanostructured Silicon Carbonitride Thin Films”, Journal of Luminescence 196, 504-510 (2018); doi: 10.1016/j.jlumin.2017.12.011
J. W. Miller, Z. Khatami, J. Wojcik, J. D. B. Bradley, and P. Mascher, “Integrated ECR-PECVD and Magnetron Sputtering System for Rare-Earth-Doped Si-Based Materials”, Surface and Coatings Technology 336, 99 – 105 (2018); doi: 10.1016/j.surfcoat.2017.08.051
Khatami, G. B. F. Bosco, J. Wojcik, L. R. Tessler, and P. Mascher, “Influence of Deposition Conditions on the Characteristics of Luminescent Silicon Carbonitride Thin Films”, ECS Journal of Solid State Science and Technology 7, N7-N14 (2018); doi:10.1149/2.0151802jss
Z. Khatami, C. Nowikow, J. Wojcik, and P. Mascher, “Annealing of Silicon Carbonitride Nanostructured Thin Films: Interdependency of Hydrogen Content, Optical, and Structural Properties”, J. Mater. Sci. 53, 1497 – 1513 (2018); doi: 10.1007/s10853-017-1576-6
Zhiyuan Chen, Yuqian Chen, Quankun Zhang, Xiuqin Tang, Dandan Wang, Zhiquan Chen, Peter Mascher, and Shaojie Wang, “Vacancy-induced ferromagnetic behavior in antiferromagnetic NiO nanoparticles with core-shell magnetic structure: A positron annihilation study”, ECS Journal of Solid State Science and Technology 6, P798 – P804 (2017); doi: 10.1149/2.0081712jss
Toshihiko Shibanuma, Takayuki Matsui, Jacek Wojcik, Peter Mascher, Pablo Albella, and Stefan A. Maier, “Experimental demonstration of tuneable directional scattering of visible light from all-dielectric asymmetric dimer”, ACS Photonics 4, 489 – 494 (2017); doi: 10.1021/acsphotonics.6b00979
Toudert, Johann; Serna, Rosalia; Camps, Iván; Wojcik, Jacek; Mascher, Peter; Rebollar, Esther; Ezquerra, Tiberio, “Unveiling the Far Infrared – to – Ultraviolet Optical Properties of Bismuth for Applications in Plasmonics and Nanophotonics”, The Journal of Physical Chemistry C 121, 3511 – 3521 (2017); doi: 10.1021/acs.jpcc.6b10331
Zhi-Yuan Chen, Yuqian Chen, Q. K. Zhang, N. Qi, Z.Q. Chen, P. H. Li, Peter Mascher, and S.J. Wang, “Defect evolution and their impact on the ferromagnetism of Cu-doped ZnO nanocrystals upon thermal treatment: A positron annihilation study”, Journal of Applied Physics 121, 025703 (2017); doi: 10.1063/1.4973960
Z. Khatami, P. R. J. Wilson, J. Wojcik, and P. Mascher, “The influence of carbon on the structure and photoluminescence of amorphous SiCN thin films”, Thin Solid Films 622, 1-10 (2017); doi: 10.1016/j.tsf.2016.12.014
Michal M Klak; Grzegorz Zatryb; Jacek Wojcik; Jan Misiewicz; Peter Mascher; Artur Podhorodecki, “Mechanism of enhanced photoluminescence of Tb ions in hydrogenated silicon rich silicon oxide films”, Thin Solid Films 611, 62-67 (2016); doi: 10.1016/j.tsf.2016.04.050
J. M. Ramírez, A. Ruiz-Caridad, J. Wojcik, A. M. Gutierrez, S. Estradé, F. Peiró, P. Sanchís, P. Mascher, and B. Garrido, “Bright and tunable luminescence from Ce3+ and Tb3+ codoped SiOxNy thin films: Role of nitrogen content, annealing temperature and sample morphology”, Journal of Applied Physics 119, 113108 (2016); doi: 10.1063/1.4944433
Lee, Bo Mi; Yoo, Seung Il; Kang, Jin Sung; Yoon, Ju An; Kim, Woo Young; Mascher, Peter, “Hybrid Blue Organic Light Emitting Diodes with Fluorescent and Phosphorescent Emitters along with an Interlayer”, Science of Advanced Materials 8, 301-306 (2016); doi: 10.1166/sam.2016.2483
G. Zatryb, M. Klak, J. Wojcik, J. Misiewicz, P. Mascher, and A. Podhorodecki, “Effect of hydrogen passivation on the photoluminescence of Tb ions in silicon rich silicon oxide films”, Journal of Applied Physics 118, 243104 (2015); doi: 10.1063/1.4939199
G. Zatryb, P.R.J. Wilson, J. Wojcik, J. Misiewicz, P. Mascher, and A. Podhorodecki, “Raman scattering from confined acoustic phonons of silicon nanocrystals in silicon oxide matrix”, Physical Review B 91, 235444 (2015); doi: 10.1103/PhysRevB.91.235444
Joan Manel Ramírez, Jacek Wojcik, Yonder Berencén, Alícia Ruiz-Caridad, Sònia Estradé, Francesca Peiró, Peter Mascher, and Blas Garrido, “Amorphous sub-nanometer Tb-doped SiOxNy/SiO2 Superlattices for Optoelectronics”, Nanotechnology 26, 085203, 7 pages (2015); doi:10.1088/0975-4484/26/8/085203; PubMed ID: 25656362
