Publications (26)
PDE foundation models are skillful AI weather emulators for the Martian atmosphere
Johannes Schmude, Sujit Roy, Liping Wang +10
We show that AI foundation models that are pretrained on numerical solutions to a diverse corpus of partial differential equations can be adapted and fine-tuned to obtain skillful…
Learning and Recognizing Archeological Features from LiDAR Data
Conrad M Albrecht, Chris Fisher, Marcus Freitag +4
We present a remote sensing pipeline that processes LiDAR (Light Detection And Ranging) data through machine & deep learning for the application of archeological feature detection…
Event Clustering & Event Series Characterization on Expected Frequency
Conrad M Albrecht, Marcus Freitag, Theodore G van Kessel +2
We present an efficient clustering algorithm applicable to one-dimensional data such as e.g. a series of timestamps. Given an expected frequency , we introduce an $\mathc…
Thermal infrared emission reveals the Dirac point movement in biased graphene
Marcus Freitag, Hsin-Ying Chiu, Mathias Steiner +2
Graphene is a 2-dimensional material with high carrier mobility and thermal conductivity, suitable for high-speed electronics. Conduction and valence bands touch at the Dirac point…
Surya: Foundation Model for Heliophysics
Sujit Roy, Johannes Schmude, Rohit Lal +30
Heliophysics is central to understanding and forecasting space weather events and solar activity. Despite decades of high-resolution observations from the Solar Dynamics Observator…
Role of Single Defects in Electronic Transport through Carbon Nanotube Field-Effect Transistors
Marcus Freitag, Sergei V. Kalinin, Dawn A. Bonnell +1
The influence of defects on electron transport in single-wall carbon nanotube field effect transistors (CNFETs) is probed by combined scanning gate microscopy (SGM) and scanning im…
Photocurrent imaging and efficient photon detection in a graphene transistor
Fengnian Xia, Thomas Mueller, Roksana Golizadeh-mojarad +5
We measure the channel potential of a graphene transistor using a scanning photocurrent imaging technique. We show that at a certain gate bias, the impact of the metal on the chann…
Energy dissipation in graphene field-effect transistors
Marcus Freitag, Mathias Steiner, Yves Martin +4
We measure the temperature distribution in a biased single-layer graphene transistor using Raman scattering microscopy of the 2D-phonon band. Peak operating temperatures of 1050 K…
SuryaBench: Benchmark Dataset for Advancing Machine Learning in Heliophysics and Space Weather Prediction
Sujit Roy, Dinesha V. Hegde, Johannes Schmude +22
This paper introduces a high resolution, machine learning-ready heliophysics dataset derived from NASA's Solar Dynamics Observatory (SDO), specifically designed to advance machine…
Carbon nanotubes as a tip calibration standard for electrostatic scanning probe microscopies
Sergei V. Kalinin, Marcus Freitag, A. T. Johnson +1
Scanning Surface Potential Microscopy (SSPM) is one of the most widely used techniques for the characterization of electrical properties at small dimensions. Applicability of SSPM…
Carrier scattering, mobilities and electrostatic potential in mono-, bi- and tri-layer graphenes
Wenjuan Zhu, Vasili Perebeinos, Marcus Freitag +1
The carrier density and temperature dependence of the Hall mobility in mono-, bi- and tri-layer graphene has been systematically studied. We found that as the carrier density incre…
AI Foundation Model for Heliophysics: Applications, Design, and Implementation
Sujit Roy, Talwinder Singh, Marcus Freitag +14
Deep learning-based methods have been widely researched in the areas of language and vision, demonstrating their capacity to understand long sequences of data and their usefulness…
Photocurrent in graphene harnessed by tunable intrinsic plasmons
Marcus Freitag, Tony Low, Wenjuan Zhu +3
Graphene's optical properties in the infrared and terahertz can be tailored and enhanced by patterning graphene into periodic metamaterials with sub-wavelength feature sizes. Here…
Wafer-scale Epitaxial Graphene Growth on the Si-face of Hexagonal SiC (0001) for High Frequency Transistors
Christos Dimitrakopoulos, Yu-Ming Lin, Alfred Grill +12
Up to two layers of epitaxial graphene have been grown on the Si-face of two-inch SiC wafers exhibiting room-temperature Hall mobilities up to 1800 cm^2/Vs, measured from ungated,…
Mid-infrared plasmons in scaled graphene nanostructures
Hugen Yan, Tony Low, Wenjuan Zhu +6
Plasmonics takes advantage of the collective response of electrons to electromagnetic waves, enabling dramatic scaling of optical devices beyond the diffraction limit. Here, we dem…
Photoconductivity of biased graphene
Marcus Freitag, Tony Low, Fengnian Xia +1
Graphene is a promising candidate for optoelectronic applications such as photodetectors, terahertz imagers, and plasmonic devices. The origin of photoresponse in graphene junction…
Device modeling of long-channel nanotube electro-optical emitter
J. Tersoff, Marcus Freitag, James C. Tsang +1
We present a simple analytic model of nanotube electro-optical emitters, along with improved experimental measurements using PMMA-passivated devices with reduced hysteresis. Both t…
Substrate Sensitive Mid-Infrared Photoresponse in Graphene
Marcus Freitag, Tony Low, Luis Martin-Moreno +3
We report mid-infrared photocurrent spectra of graphene nanoribbon arrays on SiO2 dielectrics showing dual signatures of the substrate interaction. First, hybrid polaritonic modes…
Infrared Spectroscopy of Wafer-Scale Graphene
Hugen Yan, Fengnian Xia, Wenjuan Zhu +5
We report on spectroscopy results from the mid- to far-infrared on wafer-scale graphene, grown either epitaxially on silicon carbide, or by chemical vapor deposition. The free carr…
Tip-gating Effect in Scanning Impedance Microscopy of Nanoelectronic Devices
Sergei V. Kalinin, Dawn A. Bonnell, Marcus Freitag +1
Electronic transport in semiconducting single-wall carbon nanotubes is studied by combined scanning gate microscopy and scanning impedance microscopy (SIM). Depending on the probe…
Layer Number Determination and Thickness-dependent Properties of Graphene Grown on SiC
Wenjuan Zhu, Christos Dimitrakopoulos, Marcus Freitag +1
The electronic properties of few-layer graphene grown on the carbon-face of silicon carbide (SiC) are found to be strongly dependent on the number of layers. The carrier mobility i…
How does the substrate affect the Raman and excited state spectra of a carbon nanotube?
Mathias Steiner, Marcus Freitag, James C. Tsang +4
We study the optical properties of a single, semiconducting single-walled carbon nanotube (CNT) that is partially suspended across a trench and partially supported by a SiO2-substr…
Climatic & Anthropogenic Hazards to the Nasca World Heritage: Application of Remote Sensing, AI, and Flood Modelling
Masato Sakai, Marcus Freitag, Akihisa Sakurai +2
Preservation of the Nasca geoglyphs at the UNESCO World Heritage Site in Peru is urgent as natural and human impact accelerates. More frequent weather extremes such as flashfloods…
Cooling of photoexcited carriers in graphene by internal and substrate phonons
Tony Low, Vasili Perebeinos, Raseong Kim +2
We investigate the energy relaxation of hot carriers produced by photoexcitation of graphene through coupling to both intrinsic and remote (substrate) surface polar phonons using t…
Manipulating infrared photons using plasmons in transparent graphene superlattices
Hugen Yan, Xuesong Li, Bhupesh Chandra +6
Superlattices are artificial periodic nanostructures which can control the flow of electrons. Their operation typically relies on the periodic modulation of the electric potential…
TensorBank: Tensor Lakehouse for Foundation Model Training
Romeo Kienzler, Leonardo Pondian Tizzei, Benedikt Blumenstiel +9
Storing and streaming high dimensional data for foundation model training became a critical requirement with the rise of foundation models beyond natural language. In this paper we…