387 citations · 1.6k across the 30 of their papers we have counts for
21 papers · 1 filter
Charge-state control of carbon-related optical absorption in AlN
Helen C. Robinson, Daniil Danilin, Md Shafiqul Islam Mollik +5
Sub-bandgap optical absorption in AlN between 2 eV and 4 eV is widely observed, but its microscopic origin remains contested. Using photo-induced electron paramagnetic resonance (p…
Self-compensation by silicon centers in ultrawide-bandgap nitrides
John L. Lyons, Darshana Wickramaratne
\textit{DX} behavior limits -type carrier concentrations in ultrawide-bandgap nitrides such as aluminum nitride (AlN) and cubic boron nitride (-BN). Instead of acting as effe…
Effects of altermagnetic order, strain and doping in RuO
Darshana Wickramaratne, Marc Currie, Shelby S. Fields +2
RuO, one of the most widely studied transition metal oxides, was recently predicted to host a novel form of collinear magnetic order referred to as altermagnetism. In this stud…
Nonradiative quenching of EPR signals in germanium-doped AlGaN: evidence for DX-center formation
Jason Forbus, Darshana Wickramaratne, John L. Lyons +1
We present photo-electron paramagnetic resonance (EPR) measurements and first-principles calculations that indicate germanium (Ge) is a DX-center in AlGaN. Our photo-EPR measuremen…
Direct evidence for carbon incorporation on the nitrogen site in AlN
Darshana Wickramaratne, Mackenzie Siford, Md Shafiqul Islam Mollik +2
We use photo-electron paramagnetic resonance (EPR) measurements and first-principles calculations to identify and explain the properties of carbon in AlN. We present clear evidence…
Assessing the SCAN functional for deep defects and small polarons in wide-bandgap semiconductors and insulators
Darshana Wickramaratne, John L. Lyons
We find the recently developed strongly constrained and appropriately normed (SCAN) functional, now widely used in calculations of many materials, is not able to reliably describe…
The deep-acceptor nature of the chalcogen vacancies in 2D transition-metal dichalcogenides
Shoaib Khalid, Bharat Medasani, John L. Lyons +2
Chalcogen vacancies in the semiconducting monolayer transition-metal dichalcogenides (TMDs) have frequently been invoked to explain a wide range of phenomena, including both uninte…
Nontrivial doping evolution of electronic properties in Ising-superconducting alloys
Wen Wan, Darshana Wickramaratne, Paul Dreher +3
Transition metal dichalcogenides offer unprecedented versatility to engineer 2D materials with tailored properties to explore novel structural and electronic phase transitions. In…
Laser-patterned submicron Bi2Se3-WS2 pixels with tunable circular polarization at room temperature
Zachariah Hennighausen, Darshana Wickramaratne, Kathleen M. McCreary +7
Characterizing and manipulating the circular polarization of light is central to numerous emerging technologies, including spintronics and quantum computing. Separately, monolayer…
Metallic vs. Semiconducting Properties of Quasi-One-Dimensional Tantalum Selenide van der Waals Nanoribbons
Fariborz Kargar, Andrey Krayev, Michelle Wurch +7
We conducted a tip-enhanced Raman scattering spectroscopy (TERS) and photoluminescence (PL) study of quasi-1D TaSe3 nanoribbons exfoliated onto gold substrates. At a selenium defic…
Stacking-Dependent Optical Properties in Bilayer WSe2
Kathleen M. McCreary, Madeleine Phillips, Hsun-Jen Chuang +4
The twist angle between the monolayers in van der Waals heterostructures provides a new degree of freedom in tuning material properties. We compare the optical properties of WSe2 h…
Role of carbon and hydrogen in limiting -type doping of monoclinic (AlGa)O
Sai Mu, Mengen Wang, Joel B. Varley +3
We use hybrid density functional calculations to assess n-type doping in monoclinic (AlGa)O alloys. We focus on Si, the most promising donor dopant, and study t…
Nonrad: Computing Nonradiative Capture Coefficients from First Principles
Mark E. Turiansky, Audrius Alkauskas, Manuel Engel +5
Point defects in semiconductor crystals provide a means for carriers to recombine nonradiatively. This recombination process impacts the performance of devices. We present the Nonr…
Chiral charge-density wave in TiSe due to photo-induced structural distortions
Darshana Wickramaratne, Richard Schaller, Gary Wiederrecht +2
A variety of experiments have been carried out to establish the origin of the chiral charge-density wave transition in 1T-TiSe, which in turn has led to contradictory conclusio…
Impact of biaxial and uniaxial strain on VO
Darshana Wickramaratne, Noam Bernstein, I. I. Mazin
Using first-principles calculations we determine the role of compressive and tensile uniaxial and equibiaxial strain on the structural, electronic and magnetic properties of VO…
The role of defects in the metal-insulator transition in VO and VO
Darshana Wickramaratne, Noam Bernstein, I. I. Mazin
The vanadates VO and VO are prototypical examples of strongly correlated materials that exhibit a metal-insulator transition. While the phase transitions in these mater…
Defect identification based on first-principles calculations for deep level transient spectroscopy
Darshana Wickramaratne, Cyrus E. Dreyer, Bartomeu Monserrat +4
Deep level transient spectroscopy (DLTS) is used extensively to study defects in semiconductors. We demonstrate that great care should be exercised in interpreting activation energ…
Interlayer Transport through a Graphene / Rotated-Boron-Nitride / Graphene Heterostructure
Supeng Ge, K. M. Masum Habib, Amrit De +4
Interlayer electron transport through a graphene / hexagonal boron-nitride (h-BN) / graphene heterostructure is strongly affected by the misorientation angle of the h-BN with r…
Interlayer Resistance of Misoriented MoS2
Kuan Zhou, Darshana Wickramaratne, Supeng Ge +3
Interlayer misorientation in transition metal dichalcogenides alters the interlayer distance, the electronic band structure, and the vibrational modes, but, its effect on the inter…
Mexican Hat and Rashba Bands in Few-Layer van der Waals Materials
Darshana Wickramaratne, Ferdows Zahid, Roger K. Lake
The valence band of a variety of few-layer, two-dimensional materials consists of a ring of states in the Brillouin zone. The energy-momentum relation has the form of a `Mexican ha…
Electronic and Thermoelectric Properties of Few-Layer Transition Metal Dichalcogenides
Darshana Wickramaratne, Ferdows Zahid, Roger K. Lake
The electronic and thermoelectric properties of one to four monolayers of MoS, MoSe, WS, and WSe are calculated. For few layer thicknesses,the near degenera…