SCOPE

2D transition metal dichalcolgenide (TMD or MX2) materials are considered as the new way forward towards realizing all the promises made by graphene. The European funded project 2Dfun (2D functional MX2/graphene hetero-structures), tries to get the best out of these materials by combing the best of their properties into functional devices, and this in a high-volume manufacturable way. The goal of this workshop is to report out our first year results to the public. By combining this with the insights and learning from top-notch experts from abroad, this one-day workshop should give an up-to-date overview of the most relevant aspects of this fascinating new class of functional materials: growth and characterization of MX2 layers, modelling and device results. The workshop will be hosted by imec, an independent world-leading research institute for nanoelectronics (www.imec.be) on Friday 14 October in Leuven, Belgium, in conjunction with imec’s Partner Technical Week.
 

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PROGRAM OF THE WORKSHOP

     
     
 08:30u - 08:40u      Welcome Matty Caymax | imec
 08:40u - 09:05u Overview MX2 depostion by ALD and CVD methods Annelies Delabie/ Yoann Tomczak | imec
 09:05u - 09:30u       2D materials: gate stack and device study through a lab-to-fab platform  Dennis Lin | imec
 09:30u - 09:55u A two-step approach for synthesis of atomically thin MoS2 using Atomic Layer Depostion Akhil Sharma | Tu/e
 09:55u - 10:20u Functionalization of 2D materials: the molecular approach Steven De Feyter/ Brandon Hirsch | KU Leuven    
 10:20u - 10:50u Coffee break  
 10:50u - 11:15u Band- and defect-related electron states in few-ML MX2 materials Valery Afanas'ev | Ku Leuven
 11:15u - 11:40u Modeling of MX2 materials: Electronic structure of interfaces, defects and adsorbates Michel Houssa | Ku Leuven
 11:40u - 12:05u Operando XPS characterization of MX materials and devices Sefik Suzer | Bilkent University
 12:05u - 12:30u Depostion of 2D materials and heterostructures: Technology and processes Ravi Sundaram | Oxford Instruments
 12:30u - 13:30u Lunch break  
 13:30u - 14:05u Molecular beam epitaxy of 2D semiconductors and topological semimetals for quantum technologies Athanasios Dimoulas | NCSR
 14:05u - 14:40u Electrical contacts with transition metal dichalcogenides Francois Peeters | University of Antwerp
 14:40u - 15:15u 2D material-based applications: an overview through a simulation approach Gianluca Fiori | University of Pisa
 15:15u - 15:45u Coffee break  
 15:45u - 16:20u Electronic, Thermal and Unconventional Applications of 2D Materials Eric Pop | Stanford University
 16:20u - 16:55u From Black Phosphorus to Phosphorene Peide (Peter) Ye | Purdue University
 16:55u - 17:05u Closure Matty Caymax | imec

 

Overview MX2 deposition by ALD and CVD methods
Two-dimensional (2D) materials, with graphene as the most studied representative, are an interesting class of materials with layered structures based on van der Waals interactions. A wide variety of 2D materials exists with highly versatile properties, that moreover can be tunable through the composition and number of layers. Therefore, 2D materials are under investigation for numerous applications, including nano-electronics, opto-electronics, energy stor¬age, and catalysis. In particular, the availability of semiconducting, insulating, metallic, and semi-metallic 2D materials is of interest for nano-electronic applications.
Several device concepts are being investigated with 2D materials obtained by micromechanical exfoliation from crystals. However, mechanical exfoliation is not suitable for industrial fabrication, which requires deposition over large area substrates. Thus, exploiting the potential of 2D materials in nano-electronic devices and enabling their integration in industrial applications requires the development of industrially relevant deposition techniques for 2D materials with well controlled structure and number of layers. Deposition techniques are currently under extensive investigation, including Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD), Molecular Beam Epitaxy (MBE) and others. ALD is of particular interest because its deposition principle ensures growth control at the atomic level on large area substrates and its low deposition temperature. This presentation will give an overview of the CVD and ALD processes for semiconducting transition metal dichalcogenides.
Annelies Delabie/Yoann Tomczak – imec
Annelies Delabie obtained a master degree in chemistry in 1997, and a PhD degree in science in 2001 from the KU Leuven (University of Leuven) in Belgium. In 2001, she joined imec, the research institute for nano-electronics and nanotechnology in Belgium. As a senior scientist, she investigates the fundamentals and applications of thin films and their deposition techniques, with a focus on Atomic Layer Deposition (ALD) and Chemical Vapor Deposition (CVD). Since 2012, she is also appointed associate professor at the chemistry department of the KU Leuven, where she started the research group “Nano-engineered Thin Films”.
2D materials: gate stack and device study through a lab-to-fab platform
In this presentation we will report and analyze the gate stack properties and device performance statistics obtained through IMEC’s lab-to-fab platform, focusing on synthetic 2-D materials (graphene and MoS2).
Dennis Lin – imec
Dennis H.C. Lin received the B.S.E.E. degree from the National Taiwan University in 1999 and the M.S.E.E. and Ph.D. degrees from Purdue University in 2000 and 2008. From 2001 to 2003, he was a Member of the Technical Staff (MTS-1) with Bell Laboratories–Lucent Technologies in New Jersey developing Soliton-based DWDM (Dense Wave Division Multiplexing) optical communication systems. His Ph.D. work was on GaAs and InGaAs based MOS devices with atomic layer deposited high-κ dielectrics. He has been engaged in gate stack research and development for advanced logic applications since 2009. He is currently the team leader of the Exploratory Device team at IMEC.
A two-step approach for synthesis of atomically thin MoS2 using Atomic Layer Deposition
Molybdenum disulphide (MoS2) is emerging as one of the most promising 2D materials amongst the class of transition metal dichalcogenides. Its ultrathin layered structure and a direct band gap of 1.9 eV in the monolayer regime makes MoS2 a very suitable candidate for a wide array of future (opto-) electronic applications. One of the major current challenges is to synthesize high quality MoS2 with accurate thickness control over a large area. Atomic layer deposition (ALD) offers precise thickness control at the atomic level with excellent wafer scale uniformity. ALD therefore could be instrumental in realizing large area 2D MoS2 with monolayer growth control and could therefore be a superior alternative to the most widely used synthesis techniques like exfoliation and chemical vapor deposition.
In this contribution, we use a combination of ALD and thermal sulphurization to synthesize 2D-MoS2. In the first step, ultrathin films of MoO3 were deposited by PE-ALD using halide-free chemistry on thermal SiO2 substrates at 200 °C with a growth rate of 0.8 Å/cycle [1]. The TEM analysis revealed that the ALD grown MoO3 films as thin as down to ~2 nm were closed and uniform in nature. The second step involved atmospheric pressure thermal sulphurization at 600°C - 700°C which transformed the ALD grown MoO3 ultrathin films into mono- or few-layered MoS2 films. There was a clear correlation between thickness of these resulting final MoS2 thin films and initial thickness of ALD grown MoO3 films which could be precisely controlled just by tuning the number of ALD cycles.
Raman spectroscopy, as performed on various thicknesses of MoS2 films showed a clear variation in the frequency difference value (Δk) between the two vibrational modes observable at 408 cm-1 and 382 cm-1 for MoS2 in bulk regime. The ‘Δk’ monotonically decreased down to 20.64 cm-1 with decreasing layer thickness which corresponds to a monolayer. The photoluminescence spectroscopy results were in line with these results, showing a strong peak at ~1.9 eV corresponding to the direct band gap transition for the thinnest (few- to mono-layer) samples. Furthermore, XPS analysis showed the core level binding energy values for Mo3d and S2p identical to the atomically thin MoS2 films reported in the literature. These results demonstrate the viability of our two-step approach based on thermal sulphurization of ALD grown metal oxide for the controllable, large area synthesis of 2D MoS2 thin films.

Akhil Sharma – TU/e
PhD student at Eindhoven University of technology (Applied Physics department, Plasma and materials processing group) The Netherlands.
Functionalization of 2D materials: the molecular approach
Monolayers of molecules can be formed at a variety of interfaces, including on top of 2D materials, for instance by depositing a solution of the compound of interest on top of the substrate (drop casting) or by immersing the substrate into a solution (dip coating).
Advanced interface specific methods such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM) provide structural and other types of information at the nanoscopic level.
In this presentation, I focus on the functionalization of graphite and graphene using two approaches. A first approach is based on molecular self-assembly at the interface between a liquid or air, and graphite or graphene. I will discuss concepts of nanostructuring these surfaces via the self-assembly approach, focusing on the effect of solvent, solute concentration and temperature, stimulus-driven self-assembly and self-assembly under nanoconfinement conditions, bringing insight into thermodynamic and kinetics aspects. A second approach is based on grafting molecules on graphite or graphene via covalent chemistry. In addition to a discussion on the functionalization principles, it will be demonstrated how nanolithography can be used to nanostructure such surfaces.
Various applications will be presented, including molecule modified graphene field effect transistors.
Steven De Feyter/Brandon Hirsch – KU Leuven
Steven De Feyter is full professor, since 2011, at KU Leuven – University of Leuven in Belgium. His current interests include the study of supramolecular chemistry and self-assembly phenomena at surfaces, including modification of 2D materials, with a focus on liquid-solid interfaces. In 2013, he was awarded an ERC advanced grant. He is associate editor of Chemical Communications.
Band- and defect-related electron states in few-ML MX2 materials
Electron states in few-monolayer (ML) MS2 compounds (M: Mo, W) are investigated using experimental techniques sensitive to band states (internal photoemission, IPE) and to the localized states, e.g., defects and impurities, (electron spin resonance, ESR). IPE spectra from 2- and 4-ML thick MoS2 and WS2 layers fabricated on SiO2 by high-temperature metal sulfurization suggest that the top of the valence band in these films is at the same energy with respect to the oxide conduction band. However, water-based layer transfer causes shift of the MoS2 bands indicating generation of additional charges at the MS2/SiO2 interface. Intrinsic defects in the sulfurization-grown MoS2 layers are found by ESR which density correlates with the density of grain boundaries in the polycrystalline film. In the natural MoS2 crystals, ESR reveals the presence of shallow acceptors associated with As impurity suggesting arsenic as a suitable p-type dopant for MoS2.
Valery Afanas’ev
Valery Afanas’ev obtained his PhD degree in Physics from Leningrad State University in 1985. Since then he was working in the Leningrad University, Technical University of Delft (the Netherlands), and University of Erlangen (Germany). He is currently professor in the Department of Physics and Astronomy at the University of Leuven (Belgium) where he heads the Semiconductor Physics Laboratory. His research focus on development of spectroscopic techniques suitable for characterization of electron states in thin solid films and their interfaces. In particular, methods based on excitation of electrons by electromagnetic waves are shown to be capable of characterization of energy distribution of fundamental (band-related) states as well as defects and impurities at interfaces of various semiconductors and oxide insulators. These methods are currently applied to investigation of electron states in 2D materials.
Modeling of MX2 materials: Electronic structure of interfaces, defects and adsorbates
In this talk, we will present first-principles calculations of various point defects in single layer MS2 (M: Mo, W, Hf), with a focus on their impact on the electronic structure of these materials. The isotropic g-values of different defects in MoS2 have also been computed, and compared to recent experimental results on MoS2 layers, grown from the sulfurization of Mo layers. A specific ESR signal, with an isotropic g-value of about 2.002, is tentatively assigned to a S antisite defect. The adsorption of oxygen atoms and hydroxyl groups on pristine and defective single MS2 layers is also investigated, using first-principles molecular dynamics simulations. In the specific case of HfS2, oxygen is found to penetrate through the layer and to substitute S atoms, forming Hf-O bonds, which strongly affects the electronic properties of the material. In the case of defective layers (with S vacancies), the O atoms are found to “passivate” the vacancies, by removing the S vacancy related gap states. Upon hydroxyl adsorption on pristine MS2 layers, S-O-H bonds are formed and are predicted to result in spin-polarized gap states.
Michel Houssa – KU Leuven
Michel Houssa obtained his PhD degree in Physics from the University of Liège, Belgium, in 1996. He is Professor in the Department of Physics and Astronomy at the University of Leuven (Belgium). His current research interest focus on the first-principles modeling of various materials, including semiconductor/oxide interfaces, two dimensional materials (silicene, germanene, transition metal dichalcogenides,...) and their heterostructures. He has authored or co-authored about 350 publications, including 10 book chapters and 10 invited review articles and has given about 50 invited talks and seminars. He has been co-organizer of several international Symposiums and Conferences, including the Symposium on Semiconductors, Dielectrics, and Metals for Nanoelectronics of the Electrochemical Society (ECS) and the IEEE Semiconductor Interface Specialists Conference. He is an ECS Fellow and a senior member of IEEE.
Operando XPS characterization of MX2 materials and devices
A noncontact chemical and electrical measurement technique of XPS is performed to investigate a number of materials and devices fabricated from 2D materials under operation. Different forms of electrical (D.C. and/or A.C.) biases are applied to purposely induce electrical potentials due either charging and/or contact resistances. The main advantage of the technique is its ability to assess element-specific surface electrical potentials of materials and devices under operation based on the energy deviation of core level peaks of the surface domains/structures. Accordingly, differences between MoS2 and WS2 moieties are detected by following the Mo3d, W4f, S2p and O1s peak shifts with respect to preparation conditions of the hetero-structures of these materials and under different biasing. Details of the technique and analyses of the spectra will be discussed, especially with respect to the electrical properties.
Sefik Suzer - Bilkent University
ŞEFİK SÜZER is a faculty member of the Department of Chemistry in the Faculty of Science, Bilkent University, Ankara, Turkey. He completed his B.S. in the Chemistry Department of the Middle East Technical University, Ankara, Turkey in 1970, and his Ph.D. in Chemistry at the University of California, Berkeley, in 1976, under the supervision of David A. Shirley. He, then, carried out postdoctoral research work at Sydney University and Freiburg University and worked in the Chemistry Department of the Middle East Technical University, before joining Bilkent University. He, served as the Chair of the Bilkent Chemistry Department between 1992-2007, spent sabbatical years in University of Virginia (1985-87), University of Michigan (2000-01), and University of Delaware (2007-08). Recipient of the Alexander von Humboldt Fellowship, Fulbright Research Scholarship, the Encouragement (1981) and Science Awards (1990) given by TÜBİTAK (The Scientific and Technological Research Council of Turkey), he was elected to the Turkish Academy of Sciences as a full-member in 1993, and has been a member of the Science Board of TÜBİTAK during 2000-08.
He had served as a member of the Editorial Board of the Journal of Electron Spectroscopy and Related Phenomena (Elsevier) during 1980-1990, and again 2008-Present. He has also served as an Editor of the Applied Surface Science (Elsevier) during 2010-2013, and is presently an Editor of the Surface Science Reports (Elsevier) and Senior-Editor of the Science Advances Today journal.
Since 1994, he has been conducting research on surface science and spectroscopy with a focus on utilization of “charging phenomena in XPS” for extracting analytical and electrical information about composite surface structures and devices using both static (d.c.) and dynamic (a.c.) voltage stimuli.
He is also very active in organization of regional and international meetings, among which European Conference on Applications of Surface and Interface Analysis, ECASIA’09 (2009), and European Conference on Surface Science, ECOSS-30 (2014), both in Antalya, Turkey have been the most known.
Deposition of 2D materials and heterostructures: Technology and processes
Vapour deposition techniques have gained a lot of interest for growth of two dimensional (2D) materials. In the recent past there has been a surge in the number of researchers studying atomic planes of other Van der Waals solids and heterostructures created by stacking layers with complementary characteristics to achieve novel functionality. For successful scaling up of prototypical applications demonstrated to date, technologies and processes for large area deposition of these materials need to be developed. Here we present the technology employed and study of the impact of process parameters on a chemical vapour deposition (CVD) process for the production of single-layer MoS2 using a gas-phase S precursor (H2S) and solid Mo precursor (MoCl5). Strategies for optimising crystalline quality via direct control of deposition variables and the impact of process parameters on defect density is analysed qualitatively using Raman spectroscopy . We also present the characteristics of CVD grown MoS2 on different substrates and investigate the use of graphene as a substrate for MoS2 growth which opens an avenue for growth of 2D heterostructures.
Ravi Sundaram – Oxford Instruments
Dr Ravi Sundaram is a Senior Development Scientist at Oxford Instruments Nanotechnology tools. He has been involved in 2d materials research in several institutions such as EPFL, Switzerland, Max Planck Institute Stuttgart, Germany, IBM Watson Research Labs, NY. He was conferred a PhD in Physics in 2011 and moved to Cambridge university as a research fellow. He joined Oxford Instruments in 2014 to lead and coordinate efforts towards 2d materials R&D.
Molecular beam epitaxy of 2D semiconductors and topological semimetals for quantum technologies
Molecular beam epitaxy is used to screen a number of 2D semiconductor materials and their van der Waals heterostructures on crystalline AlN(0001)/Si substrates with the aim to obtain large area growth with good thickness uniformity. In this presentation we will focus on the growth mode (2D or island), the structural quality, the macroscopic defect formation and the optimal band alignment between heterostructures which could be used for optoelectronic or tunnel field effect devices. Moreover, our research extends to new class of topological semimetals (TSM). While several Weyl (e.g. TaAs) or 3D Dirac (e.g. Cd3As2) semimetals have been discovered very recently, all of these adopt 3D bulk structures, not easy to produce in thin films for integration in devices. Here we are looking for epitaxial TSMs among metal dichalcogenides WTe2, MoTe2 and HfTe2 which are grown by MBE. We will present our recent evidence that HfTe2 is a Dirac semimetal. We will also discuss our ideas how we can use the chiral anomaly in these TSM thin films to make novel quantum devices for storing or processing of information.
Athanasios Dimoulas – NCSR
Dr. Dimoulas is Research Director at NCSR DEMOKRITOS in Athens and head of the MBE laboratory since 1999; presently he has an appointment as 2016 Chair of Excellence at CEA-INAC and the University of Grenoble Alpes. He received his BSc and PhD degrees from the U. of Athens and the U. Crete in Greece, respectively and he served as an EU Human Capital & Mobility fellow at the U. Groningen, Holland and research associate at CALTECH and the U. Maryland College Park, USA. He has also been a visiting research scientist at the IBM Zurich research lab in 2006 and 2007. He has coordinated several EU collaborative research projects on high-k gate dielectrics and high mobility semiconductors (Ge, InGaAs) for advanced CMOS. Since 2011, his research focuses on 2D materials (graphene, silicene, germanene and transition metal dichalcogenides) for energy efficient nanoelectronic devices and has received the ERC Advanced Grant SMARTGATE for this work. He has served as general chair of INFOS 2007 conference and TPC chair of ESSDERC 2009 as well as Process Technology subcommittee chair of IEDM 2012 and has co-organized EMRS and MRS symposia. He has 145 technical publications including four book chapters/monographs and numerous invited conference presentations. He is member of the editorial advisory board of Microelectronic Engineering, co-editor of a Springer book on “High-k gate dielectrics” and a recently published (2016) CRC press book on “2D Materials for Nanoelectronics”.
Electrical contacts with transition metal dichalcogenides
Using density functional theory in combination with nonequilibrium Green's function formalism deeper insight is obtained on different type of electrical contacts with e.g. MoS2 and MoSe2. The role of the contact structure on the electronic and transport properties is investigated. Metallic contacts with different work functions are investigated and the Schottky barrier height is obtained.
Francois Peeters – University of Antwerp
François M. Peeters received the PhD degree in physics from the University of Antwerp in 1982. He did postdoctoral research at Bell Laboratory (Murray Hill, NJ, USA) and Bell Communications Research (Red Bank, NJ, USA). He was appointed full professor at the University of Antwerp in 2000.
His areas of interests are computational modelling of mesoscopic and nanoscopic semiconductor and superconducting nanostructures, like phase transitions (structural and melting), artificial atoms (quantum dots and coupled quantum dots), graphene and other two dimensional atomic layered systems.
Peeters is a Fellow of the American Physical Society and the European Physical Society. He is a member of the Royal Flemish Academy of Belgium and of the Academia Europaea. The University of Szeged awarded him a Doctor Honoris Causa and in 2013 he was awarded the Francqui Chair. He is associate editor of Journal of Applied Physics, co-editor of Europhysics Letters and member of the excecutive editorial board of Solid State Communications. He published over 1000 papers with more than 25,000 citations and h-index 72.

 
2D material-based applications: an overview through a simulation approach
In this presentation, we will provide an overview of the potentials of 2D materials when exploited for digital, Radio Frequency and energy applications. Due to the embryonic stage of such a novel technology, simulation tools can provide relevant information in order to assess the real performance one may obtain.
In particular, we will focus on novel architectures and novel 2D materials for ultra-scaled Field Effect Transistors for digital applications, and we will suggest possible technology solutions in order to obtain high performance and high frequency devices for RF.
Finally, energy applications will be investigated as well, while comparing with Industrial requirements.
Gianluca Fiori – University of Pisa
Gianluca Fiori received the M.S. degree in electrical engineering and the Ph.D. degree from the Universita` di Pisa, Pisa, Italy, in 2001 and 2005, respectively. In autumn 2002, he visited Silvaco International, developing quantum models, which are currently implemented in the commercial simulator Atlas by Silvaco. In summers 2004, 2005, and 2008, he visited Purdue University, West Lafayette, IN, USA, where he worked on models for the simulation of transport in nanoscaled devices. Since December 2007, he has been an Assistant Professor with the Dipartimento di Ingegneria dell’Informazione, Universita` di Pisa. His main field of activity includes the development of models and codes for the simulations of ultrascaled semiconductor devices, with particular focus on two-dimensional materials based transistors. G.F. is the leading developer of the open-source code NanoTCAD ViDES (http://vides.nanotcad.com). More information available at http://gianlucafiori.org.
Electronic, Thermal, and Unconventional Applications of 2D Materials
Two-dimensional (2D) materials have applications in low-power electronics and energy-conversion systems. These are also rich domains for both fundamental discoveries as well as technological advances. This talk will present recent highlights from our research on graphene, BN, and transition metal dichalcogenides (TMDs). We have studied graphene from basic transport measurements and simulations, to the recent wafer-scale demonstration of analog dot product nanofunctions for neural networks. We are also growing and evaluating the electrical, thermal, and thermoelectric properties of TMDs including MoS2, MoSe2, HfSe2, and WTe2. Recent results include low-field resistivity and contact resistance, and high-field transport including velocity sat-uration. We have also examined the anisotropic thermal conductivity of these materials, for un-conventional applications to thermal switches and thermal routing. If time permits, I will discuss “bottom up” thermal management starting at dimensions comparable to the electron and phonon mean free paths (~100 nm), where quasi-ballistic heat flow effects dominate. Our studies reveal fundamental limits and new applications that could be achieved through the co-design and hetero-geneous integration of 2D nanomaterials.
Eric Pop – Stanford University
Eric Pop (This email address is being protected from spambots. You need JavaScript enabled to view it.) is an Associate Professor of Electrical Engineering (EE), where he leads the SystemX Heterogeneous Integration Focus Area. He was previously on the faculty of the University of Illinois Urbana-Champaign (2007-13) and also worked at Intel (2005-07). His re-search interests are at the intersection of electronics, nanomaterials, and energy. He received his PhD in EE from Stanford (2005) and three degrees from MIT (MEng and BS in EE, BS in Physics). His honors include the 2010 PECASE from the White House, and Young Investigator Awards from the ONR, NSF CAREER, AFOSR, and DARPA. He is an IEEE Senior member, he served as the General Chair of the Device Research Conference (DRC), and on program commit-tees of the VLSI, IRPS, MRS, IEDM, and APS conferences. In a past life, he was a DJ at KZSU 90.1 from 2001-04. Additional info about the Pop Lab is available online at poplab.stanford.edu.
From Black Phosphorus to Phosphorene
Phosphorus is one of the most abundant elements preserved in earth, constructing with a fraction of 0.1% of the earth crust. In general, phosphorus has several allotropes including white, red, and black phosphorus. Black phosphorus, though rarely mentioned, is a layered semiconductor and have great potentials in optical and electronic applications. Remarkably, this layered material can be reduced to one single atomic layer in the vertical direction owing to the van der Waals structure, dubbed phosphorene, where the physical properties can be tremendously different from its bulk counterpart and needed to be further explored. In this talk, we trace back to the 100 years research history on black phosphorus from the synthesis to material properties, and extend the topic from black phosphorus to phosphorene. Their electrical, optical, thermal and mechanical anisotropic properties are thoroughly studied and will be presented and reviewed.

Peide (Peter) Ye – Purdue University
Dr. Peide Ye is Richard J. and Mary Jo Schwartz Chair Professor of Electrical and Computer Engineering at Purdue University in USA. He received Ph.D. from Max-Planck-Institute of Solid State Research, Stuttgart, Germany, in 1996. Before joining Purdue faculty in 2005, he worked for NTT, NHMFL/Princeton University, and Bell Labs/Agere Systems. His current research is focused on ALD high-k integration on novel channel materials including III-V, Ge, complex oxides, graphene and other 2D crystals. He authored and co-authored more than 150 peer reviewed articles and 300 conference presentations. He is a Fellow of IEEE.