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Search Publications by: Sergiy Krylyuk (Fed)

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Displaying 1 - 25 of 77

Understanding the Origin and Implication of the Indirect-to-Direct Bandgap Transition in Multilayer InSe

May 2, 2024
Nicholas Pike, Ruth Pachter, Michael Altvater, Chris Stevens, Matthew Klein, Joshua Hendrickson, Huairuo Zhang, Sergiy Krylyuk, Albert Davydov, Nicholas Glavin
Indium selenide (InSe) multilayers have attracted much interest recently due to their electronic and optical properties, partially dependent on the existence of an indirect-to-direct bandgap transition that is correlated to the multilayer thickness. In

Isotopic effects on in-plane hyperbolic phonon polaritons in MoO3

March 4, 2024
Jeremy Schultz, Sergiy Krylyuk, Jeffrey Schwartz, Albert Davydov, Andrea Centrone
Hyperbolic phonon polaritons (HPhPs), hybrids of light and lattice vibrations in polar dielectric crystals, empower nano-photonic applications by enabling the confinement and manipulation of light at the nanoscale. Molybdenum trioxide (α-MoO3) is a

Raman Spectroscopy of Phonon States in NbTe4 and TaTe4 Quasi-1D van der Waals Crystals

February 23, 2024
Zahra Ebrahim Nataj, Fariborz Kargar, Sergiy Krylyuk, Topojit Debnath, Maedeh Taheri, Subhajit Ghosh, Huairuo Zhang, Albert Davydov, Roger Lake, Alexander Balandin
We report the results of polarization-dependent Raman spectroscopy of phonon states in single-crystalline quasi-one-dimensional NbTe4 and TaTe4 van der Waals materials. The measurements were conducted in the wide temperature range from 80 K to 560 K. Our

Single-Phase L10-Ordered High Entropy Thin Films with High Magnetic Anisotropy

November 11, 2023
Willie Beeson, Dinesh Bista, Huairuo Zhang, Sergiy Krylyuk, Albert Davydov, Gen Yin, Kai Liu
The vast high entropy alloy (HEA) composition space is promising for discovery of new material phases with unique properties. We explore the potential to achieve high magnetic anisotropy materials in single-phase HEA thin films. Thin films of FeCoNiMnCu

Emergent ferromagnetism with superconductivity in Fe(Te,Se) van der Waals Josephson junctions

October 23, 2023
Gang Qiu, Hung-Yu Hu, Lunhui Hu, Huairuo Zhang, Chi-Yen Chen, Yanfeng Lyu, Christopher Eckberg, Peng Deng, Sergiy Krylyuk, Albert Davydov, Ruixing Zhang, Kang Wang
Ferromagnetism and superconductivity are two key ingredients for topological superconductors, which can serve as building blocks of fault-tolerant quantum computers. Adversely, ferromagnetism and superconductivity are typically also two hostile orderings

Strain-activated stimulated emission from multilayer MoSe2 in a narrow operation window

September 24, 2023
Yuankun Lin, Noah Hurley, Steve Kamau, Evan Hathaway, Yan Jiang, Roberto Gonzalez Rodriguez, Sinto Varghese, Sergiy Krylyuk, Albert Davydov, Yuanxi Wang, Anupama Kaul, Jingbiao Cui
Herein, photoluminescence (PL) and fluorescence lifetime imaging (FLIM) in multilayer MoSe2 are studied. Strain-activated stimulated emission via defect levels in multilayer MoSe2 under laser excitation is observed, for the first time in defects of

Electrostatic modulation of thermoelectric transport properties of 2H-MoTe2

September 6, 2023
Tianhui Zhu, Sree Sourav Das, Safoura Nayebsadeghi, Fajana Tonni, Sergiy Krylyuk, Costel Constantin, Keivan Esfarjani, Albert Davydov, Mona Zebarjadi
Two-dimensional layered transition metal dichalcogenides are potential thermoelectric candidates with application in on-chip integrated nanoscale cooling and power generation. Here, we report a comprehensive experimental and theoretical study on the in

Mid-Infrared, Near-Infrared, and Visible Nanospectroscopy of Hydrogen-Intercalated MoO3

August 21, 2023
Jeffrey Schwartz, Sergiy Krylyuk, Devon Jakob, Albert Davydov, Andrea Centrone
Control over the local chemical composition and spatial heterogeneities in nanomaterials provides a means to impart new functions and to tailor their properties in many applications. For two-dimensional (2D) van der Waals materials, intercalation is one

The growth of self-intercalated Nb1+xSe2 by molecular beam epitaxy: The effect of processing conditions on the structure and electrical resistivity

June 8, 2023
Peter Litwin, Samantha Jaszewski, Wendy Sarney, Asher Leff, Sergiy Krylyuk, Albert Davydov, Jon Ihlefeld, Stephen McDonnell
We report on the synthesis of self-intercalated Nb1+xSe2 thin films by molecular beam epitaxy. Nb1+xSe2 is a metal-rich phase of NbSe2 where additional Nb atoms populate the van der Waals gap. The grown thin films are studied as a function of the Se to Nb

Rydberg Excitons and Trions in Monolayer MoTe2

April 12, 2023
Souvik Biswas, Aurelie Champagne, Jonah Haber, supavit pokawanvit, Joeson Wong, Hamidreza Akbari, Sergiy Krylyuk, Kenji Watanabe, Albert Davydov, Zakaria Al Balushi, Felipe H. da Jornada, Diana Qiu, Jeffrey Neaton, Harry Atwater
Monolayer transition metal dichalcogenide (TMDC) semiconductors exhibit strong excitonic optical resonances which serve as a microscopic, non-invasive probe into their fundamental properties. Like the hydrogen atom, such excitons can exhibit an entire

Phase-transition-induced Thermal Hysteresis in Type-II Weyl Semimetals MoTe2 and Mo(1-x)W(x)Te2

November 19, 2022
Md Sabbir Akhanda, Sergiy Krylyuk, Diane Dickie, Albert Davydov, Fei Han, Mingda Li, Mona Zebarjadi
The resistivity versus temperature measurement is commonly used for identifying temperature-induced phase change and the resulting hysteresis loop. While the resistance is influenced by both the density of states and the carrier lifetimes, the Seebeck

Heterojunction tunnel triodes based on two-dimensional metal selenide and three-dimensional silicon

October 27, 2022
Jinshui Miao, Chloe Leblanc, Jinjin Wang, Yue Gu, Xiwen Liu, Baokun Song, Huairuo Zhang, Sergiy Krylyuk, Weida Hu, Albert Davydov, Tyson Back, Nicholas Glavin, Deep Jariwala
Low power consumption in the static and dynamic modes of operation is a key requirement in the development of modern electronics. Tunnel field-effect transistors with direct band-to-band charge tunnelling and steep-subthreshold-slope transfer

Transport Properties of Few-Layer NbSe2: from Electronic Structure to Thermoelectric Properties

July 20, 2022
Tianhui Zhu, Peter Litwin, Md Golam Rosul, Devin Jessup, Md Sabbir Akhanda, Farjana Tonni, Sergiy Krylyuk, Albert Davydov, Petra Reinke, Stephen McDonnell, Mona Zebarjadi
4-layer NbSe2 is grown on SiO2 by molecular beam epitaxy. The in-situ X-ray photoelectron spectroscopy (XPS) measurements suggest a Nb-rich stoichiometry (Nb1+xSe2) likely due to intercalation of Nb atoms in between the NbSe2 layers. The metallic nature of

Rapid Phase Transition of Al2O3 Encapsulated MoTe2 via Thermal Annealing

July 19, 2022
Rohan Sengupta, Saroj Dangi, Sergiy Krylyuk, Albert Davydov, Spyridon Pavlidis
MoTe2 has gained a lot of attention recently as a potential phase change material candidate for low-power nonvolatile switches and high-density memory applications, due to the smallest predicted energy offset between its semiconducting 2H and semimetallic

Self-Driven Highly Responsive PN Junction InSe Heterostructure Near-Infrared Light Detector

June 30, 2022
Chandraman Patil, Chaobo Dong, Hao Wang, Hamed Dalir, Sergiy Krylyuk, Huairuo Zhang, Albert Davydov, Volker Sorger
Photodetectors converting light signals into detectable photocurrents are ubiquitously in use today. To improve the compactness and performance of next-generation devices and systems, low dimensional materials provide rich physics to engineering the light

Powder X-ray structural analysis and band gap measurements for (CaxSr2-x)MnWO6 (x = 0.25, 0.5, 0.75, 1.5, 1.75).

June 1, 2022
Winnie Wong-Ng, YuQi Yang, Yu-Cheng Lan, GuangYao Liu, Amrit Kafle, Weifang Liu, Jie Hou, Donald Windover, Qingzhen Huang, Sergiy Krylyuk, James A. Kaduk
The structure, powder diffraction patterns and band gap measurements of a series of manganese- and tungsten-containing alkaline-earth double perovskites (CaxSr2-x)MnWO6 (x=0.25, 0.5, 0.75, 1.5, 1.75) have been investigated. Powder X-ray diffraction

Electrochemically Assaying Dopamine with p-Doped Silicon Nanowires

March 14, 2022
Nawaraj Karki, Albert Davydov, Sergiy Krylyuk, Charles Chusuei
Neuroblastoma, a pediatric cancer, is characterized by high urinary excretion of dopamine (DA). Silicon nanowires (SiNWs), which are nontoxic and known to resist surface fouling in biological samples, were investigated for practical use as working

Spatially-resolved bandgap and dielectric function in two-dimensional materials from Electron Energy Loss Spectroscopy

February 15, 2022
Abel Brokkelkamp, Jaco ter Hoeve, Isabel Postmes, Sabrya van Heijst, Luigi Maduro, Albert Davydov, Sergiy Krylyuk, Juan Rojo, Sonia Conesa Boj
The electronic properties of two-dimensional (2D) materials depend sensitively on the underlying atomic arrangement down to the monolayer level. Here we present a novel strategy for the determination of the band gap and complex dielectric function in 2D

Thickness-dependent transport properties and photoresponse in MoSe2 field-effect transistors

February 4, 2022
Shiqi Guo, Sergiy Krylyuk, Hsin Y. Lee, Ratan K. Debnath, Albert Davydov, Mona E. Zaghloul
Transition metal dichalcogenides have been studied extensively due to their unique properties in low-dimensional limits. In this work, we have examined the effect of MoSe2 layer thickness on its electrical properties in a field effect transistor (FET)

Charge Density Wave Activated Excitons in MoSe2

January 5, 2022
Jaydeep Joshi, Benedikt Scharf, Igor Mazin, Sergiy Krylyuk, Daniel Campbell, Albert Davydov, Johnpierre Paglione, Igor Zutic, Patrick Vora
Layered materials enable the assembly of a new class of heterostructures where lattice-matching is no longer a requirement. Interfaces in these heterostructures therefore become a fertile ground for new physics as dissimilar phenomena can be coupled via

Low barrier height in a ZnO nanorods/NbSe2 heterostructure prepared by van der Waals epitaxy

September 9, 2021
Yeonhoo Kim, Roxanne Tutchton, Ren Liu, Sergiy Krylyuk, Jian-Xin Zhu, Albert Davydov, Young Joon Hong, Jinkyoung Yoo
Two-dimensional (2D) materials as contacts for semiconductor devices have attracted great attention due to minimizing Fermi level pinning. Schottky–Mott physics has been widely employed to design 2D material-based electrodes and to elucidate their contact

Mobility Extraction in 2D Transition Metal Dichalcogenide Devices - Avoiding Contact Resistance Implicated Overestimation

June 10, 2021
Chin-Sheng Pang, Ruiping Zhou, Xiangkai Liu, Peng Wu, Terry Y. Hung, Shiqi Guo, Mona E. Zaghloul, Sergiy Krylyuk, Albert Davydov, Joerg Appenzeller, Zhihong Chen
Schottky barrier (SB) transistors operate distinctly different from conventional metal-oxide semiconductor field-effect transistors (MOSFETs), in a unique way that the gate impacts the carrier injection from the metal source/drain contacts into the channel

Substrate-mediated hyperbolic phonon polaritons in MoO3

February 15, 2021
Jeffrey Schwartz, Son T. Le, Sergiy Krylyuk, Curt A. Richter, Albert Davydov, Andrea Centrone
Hyperbolic phonon polaritons (HPhPs) are hybrid excitations of light and coherent charge oscillations that exist in strongly optically anisotropic, two-dimensional materials (e.g., MoO3). These polaritons propagate through the material's volume with long