PhD. DAN BUCA
PhD. DAN BUCA
Group leader “Si-based epitaxy and Photonics” at Peter Grünberg Institute 9, Forschungszentrum Juelich, Germany
GeSn semiconductors for CMOS-integrated photonics and energy harvesting
The activity focus is placed on the development of GeSn and SiGeSn epitaxy for photonics, electronics and energy harvesting applications. We were the first group worldwide able to experimentally demonstrate that the GeSn alloys become fundamental direct bandgap semiconductors. The evident consequence was the proof of laser emission in GeSn on Si substrates. Advanced epitaxy developed in the group allows the demonstration first and still unique lasers like Multi quantum Wells laser, cw laser operation at low temperatures or vertical NWs GeSn/Ge nano-MOSFETs. Presently the group was able to show room temperature tensely strained GeSn lasers, electrically pumped GeSn lasers, GeSn based CMOS invertor and low thermal lattice conductivity as required for energy harvesting.
The long standing cooperation with the CEA-LETI and the epitaxy group in LETI has contributed to the development of the GeSn field and led to multiple publications and project cooperation’s.
Monolithically integrating electronic photonic and thermoelectric elements is the ultimate goal of silicon ICs. To achieve this, light sources on Si and efficient thermoelectric generators are crucial for the development of energy-efficient chips. Si photonics is also being considered as a potential technology platform for future quantum computing systems, with optical input-outputs co-integrated on CMOS chips. In addition, recent advances in Si photonics have proposed the technology as a platform for neuromorphic computing due to its large bandwidths and multiplexing capabilities. However, despite being a prominent material in the field of nano and micro-electronics, Si is not an efficient light emitter. As a result, laser research has focused on strain engineering of Ge and its group IV alloys.
Although the GeSn system has been known for some time, high-quality epitaxial layers have only recently been grown on Si substrates with the required crystalline quality for industrial applications . Laser emission at low temperatures was already demonstrated in 2015 . Over time, progress has allowed the development of GeSn lasers with different geometries like Fabry-Perot, micro-disks, or photonics crystals, although their maximum working temperature was limited to cryogenic temperatures. Through another epitaxial breakthrough, the ternary SiGeSn heterostructures and quantum well structures were developed, allowing better carrier confinement and strongly reducing the laser threshold. Additional technologies based on defects and lattice strain engineering were required to enable room temperature emission under optical pumping. This presentation will discuss how to induce tensile strain in GeSn alloys and the benefits for laser emission , .
However, achieving GeSn lasers through electrical pumping is a more challenging task that requires more elaborate layer stacking and suitable solutions for high-quality electrical contacts. In this work, we present different electrically pumped GeSn laser diodes emitting at a wavelength of 2.7 µm.
Experiments with optical and electrical pumping of lasers also revealed problems with heat dissipation in the devices. This observation led to the study of GeSn alloys for thermoelectric applications. To date, no Si-compatible semiconductor has been able to efficiently work as an energy harvester for the low-temperature range below 100°C. This aspect will also be addressed in the presentation.
 D. Grützmacher et al., Appl. Phys. A 129, 3, 1–10 (2023)
 S. Wirths et al., Nat. Photonics 9, no. 2, 88–92 (2015)
 A. Elbaz et al., Nat. Photonics 146, 14, 6, 375–382 (2020).
 D. Buca et al., Adv. Opt. Mater., 2201024 (2022).
 B. Marzban et al., ACS Photonics, 10, 217–224 (2023).
 D. Spirito et al., ACS Appl. Energy Mater., 4, 7, 7385–7392, (2021).
PhD. ANTONIO J. GARCIA LOUREIRO
PhD. ANTONIO GARCIA LOUREIRO
Associate Professor at Universidad de Santiago de Compostela
A general toolkit for advanced semiconductor transistors: from simulation to machine learning.
Antonio J. Garcia Loureiro received a MSc degree in Electronic Physics and a PhD in Electronics and Computer Science from the University of Santiago de Compostela (Spain) in 1994 and 1999, respectively. Nowadays he is a professor in the Department of Electronics, University of Santiago de Compostela. He was a visiting researcher at the Edinburgh Parallel Computing Centre-EPCC (UK), and at the Device Modeling Group in the University of Glasgow (UK).
His current research interests include the development of numerical simulators for advanced semiconductor devices, solar cells and power converters.
He has published over 100 papers in highly ranked peer-review journals, with more than half in collaboration with international partners, and has participated in more than 150 international conferences. During the last ten years, he has been principal investigator in 11 research projects/contracts, and in another 25 as a member of the research team. Also, he was director of 15 PhD thesis in this field.
This work presents an overview of a set of in-house-built software intended for state-of-the-art semiconductor device modelling, ranging from simulators to post-processing tools and prediction codes based on statistics and machine learning techniques. First, VENDES is a 3D finite-element based quantum-corrected semi-classical/classical toolbox able to characterise the performance, scalability, and variability of transistors. MLFoMPy is a Python-based tool that post-processes IV characteristics, extracting the most relevant figures of merit and preparing the data for subsequent statistical or machine learning studies. FSM is a variability prediction tool that also pinpoints the most sensitive regions of a device to the source of fluctuation. Finally, we also describe machine learning-based prediction tools that were used to obtain full IV curves and specific figures of merit of devices suffering the influence of several sources of variability.
PhD. RAKESH VAID
PhD. RAKESH VAID
Fellow IETE, Senior Member IEEE, Member ECS, Life member IAPT
Vice-Chairman – IEEE EDS Delhi Chapter
Professor and Former Head
Department of Electronics,
University of Jammu,
Performance Evaluation of Triboelectric Nanogenerators (TENG) for Wearable Electronic applications
PhD. Rakesh Vaid is presently Professor at the Department of Electronics, University of Jammu, Jammu and Kashmir, India. He is a Fulbright Fellow (FNIEAS-2022) at the George Washington University USA; Senior member of IEEE and EDS (USA) and Fellow of IETE (India).
Prof. Vaid has served as: Head, Department of Electronics, University of Jammu (2017-2020); Vice Chairman of IEEE EDS Delhi India chapter (2022-present); Chairman IETE Jammu Centre (2014-2018), Vice Chairman, IETE Jammu centre (2010-12); General secretary- Jammu University teachers association during 2013-14. He was awarded University Gold Medal University of Kashmir-1989 and Young scientist fellowship by J&K Council of Science & Technology in 1999.
Dr. Vaid has more than 100 publications to his credit in national/ international journals and conference proceedings. His area of research include Triboelectric Nanogenerator (TENG); Nano electronics & high k dielectrics; device modelling and simulation; Carbon Nanotubes and Graphene based devices; FinFETs; MOS capacitor & solar cell etc. He has successfully guided 06 Ph.D. and 06 M. Phil students besides 06 students are pursuing their Ph.D. under him. He has successfully completed a major research project sponsored by UGC, besides completed five medium term projects under Indian nanoelectronics user’s program (INUP) sponsored by CEN, IIT Bombay.
Dr Vaid has presented his research in various prestigious national/ international conferences with in India and abroad such as MIEL-2006 (Belgrade-Serbia), ICMNT-2006 (Algeria), Nano today 2013 (Singapore), MNE 2014 (Lausanne- Switzerland), 227th ECS meeting 2015 (Chicago-USA), 231st ECS meeting 2017 (New-Orleans, USA), University of Manchester, UK (June 2017), 233rd ECS meeting 2018 (Seattle-USA), IMEC (Leuven-Belgium- September 2019), IEEE MIEL 2019 (Nis-Serbia), 241st ECS meeting 2022 (Vancouver-Canada) besides visited many universities such as Stanford, Oxford, Cambridge in USA, UK and Europe.
With the growing emergence of flexible/wearable electronic devices, the requirement for portable and flexible power sources has increased many folds. Recently, energy harvesting techniques have received considerable attention due to the increasing demand to supply sustained electrical power to the electronic devices. Energy harvesting converts waste mechanical energy into useful electrical energy by employing various methods such as electromagnetic, electrostatic, and piezoelectric etc. Alternatively, a novel low-cost device known as Triboelectric Nanogenerator (TENG) is currently under consideration for the same purpose and uses contact electrification mechanisms to generate electrical output at the interface when two different surfaces of two different materials (such as polymer and metal) are rubbed against each other to develop a charge known as triboelectric charging. TENG is capable of efficiently converting a variety of mechanical energies into electricity with high conversion efficiency and has low cost, great output power and easy production. Flexible TENGs as power sources have been widely researched due to the rapidly expanding demand for flexible/wearable electronic devices, bendable displays, electronic skin etc. The output performance and mechanical stability of the flexible TENGs can be affected by two important factors: suitable materials and optimum topologies. In this presentation, we will demonstrate the fabrication and characterization of Rigid, Flexible and Multilayer TENG devices using different substrates such as ITO (Indium tin oxide) coated glass, FTO (Fluorine tin oxide) coated glass, ITO coated PET (Polyethylene terephthalate) with copper (Cu), Aluminum (Al) with gold nanoparticles (AuNPs) as a metal layers and Polydimethylsiloxane (PDMS); Poly methyl methacrylate (PMMA); Poly tetra fluoroethylene (PTFE) and Polyimide as a polymer layers. Various layers were deposited using direct current (DC) magnetron sputtering and spin-coating techniques. These metal-polymer thin layers are then joined together to fabricate different TENG devices using polyurethane as a spacer. Comparative study of the various TENG devices would be presented along with various physical (FESEM, EDAX and elemental mapping) and electrical characterizations (using linear coil actuator) to calculate open circuit voltage and short circuit currents. The open circuit voltage almost doubles as we switch from rigid to flexible TENG whereas it rises ~3 times in case of multilayered flexible TENG device. The short circuit current also increases by approx. 2.5 times from rigid and flexible TENG. Many issues pertaining to the synthesis and spraying of the gold nano-particles to enhance the surface roughness shall also be discussed.
PhD. LÉOPOLD VAN BRANDT
PhD. LÉOPOLD VAN BRANDT
Variability and Intrinsic Noise Effects in ULV CMOS SRAM Demystified
- Léopold Van Brandt was born in Belgium, in 1995. He received the B.S. and the M.S. degrees in Electrical Engineering from the Université catholique de Louvain, Louvain-la Neuve, in 2015 and 2017, respectively, and the PhD degree in Engineering Science for his dissertation entitled “Statistical Analyses of Intrinsic Noise and Variability Effects in CMOS Digital Latches” in 2022. He is currently working as a postdoctoral research fellow in the Mathematical Engineering department of the UCLouvain on the project “Thermodynamics of Circuits for Computation”.
His research interests include but are not limited to: nanoelectronics; characterization and modelling of the noise in nonlinear devices and circuits; circuit simulation theory; efficient assessment of the reliability of SRAM bitcells; stochastic thermodynamics. The interplay between research and education is one of his major concerns.
Since each Static Random Access Memory (SRAM) array typically contains hundreds of thousands of bitcells (e.g. 262 144 for 32 kB), a cell failure probability as low as the ppm must be guaranteed for a given design across various process, voltage and temperature conditions.
The MOS transistors of smallest dimensions and supplied at ultra-low voltage (ULV) are very sensitive to all types of uncertainties. As process variability has remained the major concern for now, we will firstly introduce an insightful and accurate non-Monte Carlo methodology to predict the variability-induced failure probability of subthreshold SRAM bitcells in retention mode. Secondly, the intrinsic noise of the MOS transistors, especially experimentally-reported large-amplitude random telegraph noise (RTN), is likely to induce transient bit flips in bitcells weakened by worsened voltage, temperature and process variability conditions. Because the
noise cannot be studied within a purely static formalism, we propose a rigorous simulation framework, relying on industrial SPICE tools and process design kits (PDK), to observe and explain these bit flips. Finally, extending the reliability perspective, we will conclude this talk by quantitatively discussing the relative impact of process variability, RTN and Gaussian noise in mature industrial CMOS technology such as 28nm FD SOI.
PhD. MARÍA SÁNCHEZ COLINA
PhD. MARÍA SÁNCHEZ COLINA
Faculty of Physics. University of Havana.
San Lázaro and L, Vedado, 10400.
La Habana, Cuba
Surface Photovoltage Spectroscopy characterization of laser diodes and solar cells
PhD. Sanchez’s research focus is on thermal behavior of semiconductor devices such as lasers, light-emitting diodes (LEDs), and, Quantum-Cascade Lasers. She is currently engaged in the characterization of devices by Surface Voltage Spectroscopy technique. She earned her Ph.D. in Physics from the University of Havana in 1996, for which she did a training in the laboratory of Nobel Zhores Alferov at the Ioffe Institute in St. Petersburg, Russia. She has 30 years of experience teaching physics at the University of Havana, and has also taught graduate courses at the Federal University of Minas Gerais in Brazil and in the Master in Advanced Materials, Nanotechnology and Photonics at the Autonomous University of Madrid. She has been the Editor of the Cuban Journal of Physics and Dean of the Physics Faculty at the University of Havana. Presently, Dr. Sanchez is the president of the Cuban Physical Society and the Ibero-American Federation of Physics Societies (FEIASOFI).
Surface photovoltage spectroscopy (SPS) is based on the measurement of the light-induced change in the surface voltage of a sample and is a widely used technique to study the electronic transitions and optical properties of semiconductor materials and nanostructures. This talk describes the principles and experimental details of SPS and presents results obtained in characterization of laser diodes and solar cells, demonstrating the effectiveness of this technique as a simple and non-destructive tool in the characterization not only of materials but also in semiconductor devices.
Surface photovoltage measurements were performed on fully metallized AlxGa1-xAs laser diode structures. The results show that the signatures corresponding to the electronic transitions of, the active region and the barriers can be clearly distinguished in an SPV spectrum, thus demonstrating that it is possible with this technique to obtain the band diagram of the structure without the necessity of etching away the individual layers.
SPS was also used as a control technique in the manufacturing process of Kesterite and c-Silicon solar cells. A study of the effect of different texturing processes and passivation schemes on the SPV of black silicon based solar cells is shown. Kelvin Probe Force Microscopy (KPFM) was used for direct measurement of surface potential maps.
M.Sc. JOSE IGNACIO CASTILLO
M.Sc. JOSE-IGNACIO CASTILLO
Universidad Autónoma de la Ciudad de México
Tools for the academic productivity assessment for new researchers
He has been working for 27 years in telecommunications and computer industry and academia in 100 national and international projects, as team member or leader on technical and management positions in internet networks, data centers and engineering management. In industry he worked for DICI, IFE, REDUNO-TELMEX and DATACENTER DYNAMICS, being now an independent consultant. In academia he works as a full-time professor-researcher at Autonomous University of Mexico City (UACM) since 2008, directing the Advanced Networking Laboratory; in past he was at UPAEP (99-06) & UTM (98-99). He also worked for BUAP, UAM and UDEFA (Military) Mexico and UPS Ecuador as visiting professor. He wrote 4 books, and 50 journal and conference papers. He has lectured 140 undergraduate & graduate courses. He was an IEEE Computer Society Distinguished Lecturer (2015-2017), till today, he offered 171 keynotes, invited talks and webinars, and 16 tutorials for conferences. He received his bachelor’s degree in sciences degree in Electronic Sciences and his M.Sc. Degree in Electronic Devices, both from the B. Autonomous University of Puebla, Mexico.
The measurement of academic or industry research productivity lets higher education institutions, academic research centers and industry research centers to detect opportunity areas to face challenges, improve decisions and to make better strategies for research development and innovation. For new researchers, it lets to align an academic career from junior to senior maturity level; for employers, it lets to know how aligned a researcher is to a knowledge area or how easy or not could be to integrate a researcher to a group; for investors, it lets to know if an ambitious project could be reached on time and budged.
PhD. WILFRIDO MORENO
PhD. WILFRIDO MORENO
University of South Florida, Electrical Engineering Dept.
Tampa – Florida
Mastering the Challenges: Accelerating Workforce Development in Automation & Control for the Semiconductor Industry
Dr. Wilfrido Moreno received his M.S.E.E & Ph.D. degrees in Electrical Engineering from the University of South Florida (USF), Tampa – Florida in 1985 and 1993 respectively. He is currently a Professor in the Electrical Engineering Department at the University of South Florida, Tampa – Florida. Since 1994, Dr. Moreno has been facilitating students and faculty mobility throughout the Latin American region; over 120 faculty members have earned their Doctoral degrees from USF. From 2003 to 2022, Dr. Moreno served as the R&D Initiative Director for the Ibero-American Science & Technology Education Consortium (ISTEC) responsible for fostering Teaching/Learning & Research collaborations throughout the Ibero-american region among ISTEC’s members. Dr. Moreno is a founding member of the former Center for Microelectronics Research, (CMR- 1988), which is currently the Nanotechnology Research & Education Center, (NREC). Dr. Moreno is the author of over 135 technical publications. His research interests are oriented the use of Model Based System Engineering as the basis for systems integration that provide hardware/software solutions to industrial applications in areas such as Digital Signal Processing, Communications, Energy, Robotics, Automation & Control, Nano/Micro-electronics, Medical Engineering and Multimedia solutions applied to engineering education. Dr. Moreno has supervised over sixty master students and twenty five doctoral students.