North American Conference on Molecular Beam Epitaxy, Quantum Materials Epitaxy Workshop
Prof. Gupta gave an invited oral presentation describing the wafer-scale growth of 2D materials by metalorganic chemical vapour deposition in Madison, Wisconsin on Sept. 16, 2023.
It’s Official!
On Friday, Aug. 25, 2023, Canadian 2D-Materials history was made, as the first MOCVD growth of graphene on sapphire was successfully completed in the uOttawa Aixtron CCS3X2FT Close-Coupled Showerhead MOCVD system. Watch for exciting things to come!
Summer Student Presentation Day Aug. 18, 2023
The 2D MOCVD Lab students presented their summer work in a dazzling and informative end-of-summer presentation day. Fantastic work, students!
American Conference on Crystal Growth and Epitaxy/Organometallic Vapor Phase Epitaxy (ACCGE/OMVPE)
Summer Student Aidan Karmali won first prize ($350USD) in the ACCGE/OMVPE photo contest (Digital category) for his photo “Saguaro Cactus”. The image shows an atomic force micrograph of a WS2 epilayer on sapphire. Aidan created the AFM colour scheme to honour the Arizona location of the conference and the nearby Saguaro National Park. Congratulations Aidan!
Prof Gupta co-chaired the Sixth Symposium on 2D and Low-Dimensional Materials (Sessions | ACCGE-23 / OMVPE-21 (crystalconference2023.com) in Tucson, Arizona, Aug. 13-18, 2023. He also gave an oral presentation in the III-V epitaxial growth for devices session: “Real-time, In-situ Flux Monitoring: A Revolutionary New Development in Solid-Source Molecular Beam Epitaxy“.
Prof Gupta Featured in uOttawa Faculty of Science 2021-2022 Annual Report
Departmental Colloquium Dec. 1, 2022
Dr. James Gupta
Visiting Professor
Department of Physics,University of Ottawa
1 Décembre, 2022 14h30/December 1, 2022 2:30PM
STEM364
Coffee and cookies at 14:15
Epitaxial Growth and Characterization of 2-Dimensional Quantum Materials
Abstract: The University of Ottawa has established strengths in both the experimental (LuicanMayer, Ménard) and theoretical study (Hawrylak) of two-dimensional materials, with a welldeveloped network of collaborators, including the National Research Council of Canada (Gaudreau). In this presentation I will describe an impending paradigm shift in 2D materials research which will be enabled by the establishment of new uO laboratories for the epitaxial growth (2D-MOCVD) and characterization (2D-Opto) of 2D materials on the wafer scale. In the last year, I have built a new ISO8 cleanroom featuring an Aixtron multiwafer (3X2”) close-coupled showerhead system for the growth of graphene, hexagonal boron nitride and transition metal dichalcogenides (MoS2, MoSe2, WS2, WSe2). This robust, production-proven epitaxy system uses the technique of metalorganic chemical vapour deposition (MOCVD) for the growth of highquality, highly-uniform monolayer films and heterostructures on sapphire, silicon and other substrates. In contrast with mechanically-exfoliated 2D monolayer flakes having dimensions of ~10X10 µm2, the MOCVD-grown layers cover the entire substrate surface (2X109 µm2). This capability for large-area growth will allow previously-demonstrated proof-of-concept devices to be scaled towards the development of true quantum circuits and eventual production. I will describe potential applications for these materials as single-photon emitters, “valleytronic” devices and for microelectronic Moore’s Law scaling beyond CMOS. I will also describe the capabilities of a complementary characterization laboratory (2D-Opto) which I have commissioned in the last year. The laboratory features a suite of instruments for the structural and optical characterization of 2D materials over both microscopic and wafer scales, including optical and atomic-force microscopies and confocal spectroscopic mapping instruments from room temperature to 3.3K.
Bio: Dr. James Gupta joined the uO Department of Physics as a Visiting Professor in July 2021 to establish material growth and spectroscopy laboratories for 2-dimensional quantum materials. He obtained his Ph.D. at Simon Fraser University in 1999 studying the MOCVD growth of quasi-2D monolayers of InAs in GaAs. He then worked in Santa Clara, California for n&k Technology, Inc. where he developed instruments for optical characterization of thin films in the semiconductor and hard disk industries. Over the next 21 years at the National Research Council he developed and delivered high-performance semiconductor devices for industrial clients, research applications and NASA flight missions. Dr. Gupta originated and led mid-IR laser development projects with annual budgets up to $1.4M and technical team sizes up to 20 people and was the
scientific prime for NRC’s $5M molecular beam epitaxy and characterization facility.
Visit to Tampere University, Finland, Nov. 14-17, 2022
Professor Gupta travelled to Tampere University, Finland as the opponent for the doctoral dissertation of Riku Isoaho, “Narrow Bandgap (0.7-0.9eV) Dilute Nitride Materials for Advanced Multijunction Solar Cells”
Pizza & Prof Night, Tuesday Oct. 11, 2022, 6pm
International Conference on Molecular Beam Epitaxy, Sheffield UK, Sept. 4-9. 2022
Prof Gupta gave an oral presentation in the MBE Fundamentals and Innovations session: “Real-time, In-situ Flux Monitoring: A Revolutionary New Development in Solid-Source Molecular Beam Epitaxy“
Abstract — We present a revolutionary new capability for real-time, in-situ monitoring of both group-III and group-V fluxes during solid-source molecular beam epitaxial growth. The technique is enabled by a custom MBE system design employing flux-monitoring ports deliberately positioned to monitor fluxes bypassing the substrate manipulator during growth. Bayard-Alpert ionization gauges in these ports provide real-time flux monitoring for the group-III and As fluxes, while a quadrupole mass spectrometer is used to monitor the 121Sb flux. We present compelling examples of the high signal:noise achieved during the growth of test structures on GaSb and InAs substrates, as well as during the growth of InGaAsSb/Al(In)GaAsSb laser diodes on GaSb.
International Workshop on Quantum Circuits in 2D Materials (QC2DM 2022) Ottawa, May 2022
QC2DM 2022 Workshop – Center for Quantum 2D Materials (uottawa.ca)
THIS BY INVITATION ONLY WORKSHOP, WILL BRING TOGETHER A NUMBER OF CANADIAN AND INTERNATIONALLY RECOGNIZED EXPERTS IN 2D MATERIALS, WITH A FOCUS ON THE USE OF QUANTUM DOTS FOR QUANTUM INFORMATION PROCESSING. THE WORKSHOP WILL BE HELD AT THE UNIVERSITY OF OTTAWA, STARTING MAY 25 AND ENDING ON MAY 28 2022. THE WORKSHOP IS SUPPORTED BY NSERC STRATEGIC QC2DM PROJECT, UOTTAWA CHAIR IN QUANTUM THEORY OF MATERIALS, NANOSTRUCTURES AND DEVICES, UOTTAWA CENTER FOR 2D MATERIALS (HTTPS://QC2DM.PHYSICS.UOTTAWA.CA/) AND THE NATIONAL RESEARCH COUNCIL OF CANADA.
American Conference on Crystal Growth and Epitaxy/Organometallic Vapor Phase Epitaxy 2021 Conference (ACCGE/OMVPE), Aug. 2-4, 2021 (Virtual)
Prof Gupta gave an invited oral presentation “Low-threshold InAs-based interband cascade lasers with room-temperature emission at 6.3um“, describing work done in collaboration with Prof Rui Yang and colleagues at the University of Oklahoma
Abstract – Interband cascade lasers (ICLs) are becoming a leading semiconductor laser technology for the mid-infrared because of their high efficiency and low power consumption, especially as compared with conventional diode lasers and intersubband quantum cascade lasers (QCLs) in the wavelength range from 3-5 μm. Although a greater effort has been directed towards GaSb-based ICLs in the ~3-5μm range, recent work has highlighted the exciting potential for InAs-based ICLs for reaching longer emission wavelengths.
In this work we report the development of low-threshold InAs-based ICLs with a room-temperature emission wavelength of 6.3μm. The devices were grown on n+-InAs (100) substrates by solid-source molecular beam epitaxy in a custom V90 system using valved crackers for Sb2 and As2. The ICL structures employ an improved waveguide design using intermediate AlAs/AlSb/InAs strain-balanced superlattice cladding layers surrounded by heavily-doped n+-InAs plasmonic claddings. The active region includes 15-stages with AlSb/InAs/In(0.35)Ga(0.65)Sb/InAs/AlSb type-II “W” quantum wells and optimized electron injector doping.
In pulsed mode, broad-area devices lased at 300 K at a lasing wavelength of 6.26 μm and a threshold current density of 395 A/cm2 which is the lowest ever reported among semiconductor lasers at similar wavelengths. The broad-area devices lased up to 335K in pulsed mode at a wavelength of 6.45 μm. Narrow ridge-waveguide lasers operated in continuous-wave mode with a threshold current of 52mA and output power of 1.1mW/facet at 283K. These results provide strong evidence of the potential for InAs-based ICLs as efficient sources in the mid-IR.