Thomas Siday
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View article: Optically Determined Hole Effective Mass in Tin-Iodide Perovskite Films
Optically Determined Hole Effective Mass in Tin-Iodide Perovskite Films Open
Tin-halide perovskites currently offer the best photovoltaic performance of lead-free metal-halide semiconductors. However, their transport properties are mostly dominated by holes, owing to ubiquitous self-doping. Here we demonstrate a no…
View article: The influence of subwavelength geometry on extracting the electrical properties of semiconductors by terahertz spectroscopy
The influence of subwavelength geometry on extracting the electrical properties of semiconductors by terahertz spectroscopy Open
Terahertz (THz) spectroscopy is a non-contact technique well-suited for probing the ultrafast electrical conductivity of semiconductor nanostructures, where conventional methods are often impractical. However, geometric resonances in these…
View article: Resonance-Amplified Terahertz Near-Field Spectroscopy of a Single Nanowire
Resonance-Amplified Terahertz Near-Field Spectroscopy of a Single Nanowire Open
Nanoscale material systems are central to next-generation optoelectronic and quantum technologies, yet their development remains hindered by limited characterization tools, particularly at terahertz (THz) frequencies. Far-field THz spectro…
View article: Scalable Receivers Based on Horizontally-grown InAs Nanowires Promise All-fiber Terahertz Spectrometer Systems
Scalable Receivers Based on Horizontally-grown InAs Nanowires Promise All-fiber Terahertz Spectrometer Systems Open
Nanowire-based terahertz photoconductive receivers offer many advantages over the existing bulk-based receivers, such as the capability of measuring the full terahertz polarization state and integrating into micro/nano-systems. However, th…
View article: Contrasting Ultra-Low Frequency Raman and Infrared Modes in Emerging Metal Halides for Photovoltaics
Contrasting Ultra-Low Frequency Raman and Infrared Modes in Emerging Metal Halides for Photovoltaics Open
Lattice dynamics are critical to photovoltaic material performance, governing dynamic disorder, hot-carrier cooling, charge-carrier recombination, and transport. Soft metal-halide perovskites exhibit particularly intriguing dynamics, with …
View article: Near-field probes for sensitive detectorless near-field nanoscopy in the 2.0–4.6 THz range
Near-field probes for sensitive detectorless near-field nanoscopy in the 2.0–4.6 THz range Open
Imaging and spectroscopy at terahertz (THz) frequencies have become key methods for fundamental studies across the physical sciences. With the emergence of nanoscale materials and devices, holding great promise for photonics, electronics, …
View article: Near-field imaging and spectroscopy of terahertz resonators and metasurfaces [Invited]
Near-field imaging and spectroscopy of terahertz resonators and metasurfaces [Invited] Open
Terahertz (THz) metasurfaces have become a key platform for engineering light-matter interaction at THz frequencies. They have evolved from simple metallic resonator arrays into tunable and programmable devices, displaying ultrafast modula…
View article: Ultrafast Nanoscopy of High-Density Exciton Phases in WSe<sub>2</sub>
Ultrafast Nanoscopy of High-Density Exciton Phases in WSe<sub>2</sub> Open
The density-driven transition of an exciton gas into an electron- hole plasma remains a compelling question in condensed matter physics. In two-dimensional transition metal dichalcogenides, strongly bound excitons can undergo this phase ch…
View article: Quantitative terahertz emission nanoscopy with multiresonant near-field probes
Quantitative terahertz emission nanoscopy with multiresonant near-field probes Open
By sampling terahertz waveforms emitted from InAs surfaces, we reveal how the entire, realistic geometry of typical near-field probes drastically impacts the broadband electromagnetic fields. In the time domain, these modifications manifes…
View article: Perfect absorption in GaAs metasurfaces near the bandgap edge
Perfect absorption in GaAs metasurfaces near the bandgap edge Open
Perfect optical absorption occurs in a metasurface that supports two degenerate and critically-coupled modes of opposite symmetry. The challenge in designing a perfectly absorbing metasurface for a desired wavelength and material stems fro…
View article: Near‐Field Terahertz Spectroscopy: Noninvasive Near‐Field Spectroscopy of Single Subwavelength Complementary Resonators (Laser Photonics Rev. 14(4)/2020)
Near‐Field Terahertz Spectroscopy: Noninvasive Near‐Field Spectroscopy of Single Subwavelength Complementary Resonators (Laser Photonics Rev. 14(4)/2020) Open
Subwavelength metallic resonators provide tight spatial confinement of electromagnetic fields, required for strong light-matter coupling. However far-field techniques prove to be impractical for detection of such fields. In article 1900254…
View article: Resonance-Enhanced Terahertz Nanoscopy Probes
Resonance-Enhanced Terahertz Nanoscopy Probes Open
Near-field nanoscopy at terahertz (THz) frequencies is uniquely placed to probe a multitude of physical phenomena at the nanoscale. However, at THz frequencies, the scattering efficiency of standard near-field probes is poor, limiting the …
View article: Terahertz detectors based on all-dielectric photoconductive metasurfaces
Terahertz detectors based on all-dielectric photoconductive metasurfaces Open
Performance of terahertz (THz) photoconductive devices, including detectors and emitters, has been improved recently by means of plasmonic nanoantennae and gratings. However, plasmonic nanostructures introduce Ohmic losses, which limit gai…
View article: Terahertz Detection with Perfectly-Absorbing Photoconductive Metasurface
Terahertz Detection with Perfectly-Absorbing Photoconductive Metasurface Open
Terahertz (THz) photoconductive devices are used for generation, detection, and modulation of THz waves, and they rely on the ability to switch electrical conductivity on a subpicosecond time scale using optical pulses. However, fast and e…
View article: Efficient photoconductive terahertz detector with all-dielectric optical metasurface
Efficient photoconductive terahertz detector with all-dielectric optical metasurface Open
We designed an optically thin photoconductive channel as an all-dielectric metasurface comprising an array of low-temperature grown GaAs nanobeams and a sub-surface distributed Bragg reflector. The metasurface exhibited enhanced optical ab…
View article: Resonant terahertz probes for near-field scattering microscopy
Resonant terahertz probes for near-field scattering microscopy Open
We propose and characterize a scattering probe for terahertz (THz) near-field microscopy, fabricated from indium, where the scattering efficiency is enhanced by the dipolar resonance supported by the indium probe. The scattering properties…
View article: Designing an efficient hybrid optical cavity
Designing an efficient hybrid optical cavity Open
We present an efficient terahertz (THz) detector based on an optically thin hybrid cavity. We use experimental and numerical methods to design efficient detectors, finding a hybrid cavity structure with a photoconductive (PC) layer as thin…
View article: Resonant scattering probes in the terahertz range
Resonant scattering probes in the terahertz range Open
We propose and demonstrate a novel near-field probe, resonant at terahertz (THz) frequencies. A conical metal tip, with length 50-1000 μm is fabricated directly to the surface of a semiconductor surface, acting as a radially-polarized THz …
View article: Optically thin hybrid cavity for terahertz photo-conductive detectors
Optically thin hybrid cavity for terahertz photo-conductive detectors Open
The efficiency of photoconductive (PC) devices, including terahertz detectors, is constrained by the bulk optical constants of PC materials. Here, we show that optical absorption in a PC layer can be modified substantially within a hybrid …
View article: Near-Field Spectroscopy and Imaging of Subwavelength Plasmonic Terahertz Resonators
Near-Field Spectroscopy and Imaging of Subwavelength Plasmonic Terahertz Resonators Open
We describe the temporal evolution of the terahertz (THz) field leading to the excitation of plasmonic resonances in carbon microfibers. The field evolution is mapped in space and time for the 3/2 wavelength resonance using a subwavelength…