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Articles 1 - 30 of 97
Full-Text Articles in Physics
Luminescence And Structural Properties Of Silicon-Germanium Quantum Structures Fabricated By Ion Implantation, Matheus Coelho Adam
Luminescence And Structural Properties Of Silicon-Germanium Quantum Structures Fabricated By Ion Implantation, Matheus Coelho Adam
Electronic Thesis and Dissertation Repository
The advancement of semiconductor materials has played a crucial role in driving positive technological breakthroughs that impact humanity in numerous ways. The presence of defects significantly alters the physical properties of semiconductors, making their analysis essential in the fabrication of semiconductor devices. I presented a new method to quantify surface and near-surface defects in single crystal semiconductors. Epitaxially-grown silicon was measured by low energy electron diffraction (LEED) to obtain the surface Debye temperature (θD). The results showed the surface θD of bulk Si (001), 1.0 μm, and 0.6 μm Si on sapphire of 333 K, 299 K, …
An Efficiently Excited Eu3+ Luminescent Site Formed In Eu,O-Codoped Gan, Takenori Iwaya, Shuhei Ichikawa, Volkmar Dierolf, Brandon Mitchell, Hayley Austin, Dolf Timmerman, Jun Tatebayashi, Yasufumi Fujiwara
An Efficiently Excited Eu3+ Luminescent Site Formed In Eu,O-Codoped Gan, Takenori Iwaya, Shuhei Ichikawa, Volkmar Dierolf, Brandon Mitchell, Hayley Austin, Dolf Timmerman, Jun Tatebayashi, Yasufumi Fujiwara
Physics & Engineering Faculty Publications
For the development of III-nitride-semiconductor-based monolithic micro-light-emitting diode (LED) displays, Eu,O-codoped GaN (GaN:Eu,O) is a promising material candidate for the red LEDs. The luminescence efficiency of Eu-related emission strongly depends on the local atomic structure of Eu ions. Our previous research has revealed that post-growth thermal annealing is an effective method for reconfiguring luminescent sites, leading to a significant increase in light output. We observed the preferential formation of a site with a peak at similar to 2.004 eV by the annealing process. In this study, we demonstrate that it is a previously unidentified independent site (OMVPE-X) using combined excitation-emission …
Photoluminescence Of Beryllium-Related Defects In Gallium Nitride, Mykhailo Vorobiov, Mykhailo Vorobiov
Photoluminescence Of Beryllium-Related Defects In Gallium Nitride, Mykhailo Vorobiov, Mykhailo Vorobiov
Theses and Dissertations
This study explores the potential of beryllium (Be) as an alternative dopant to magnesium (Mg) for achieving higher hole concentrations in gallium nitride (GaN). Despite Mg prominence as an acceptor in optoelectronic and high-power devices, its deep acceptor level at 0.22 eV above the valence band limits its effectiveness. By examining Be, this research aims to pave the way to overcoming these limitations and extend the findings to aluminum nitride and aluminum gallium nitride (AlGaN) alloy. Key contributions of this work include. i)Identification of three Be-related luminescence bands in GaN through photoluminescence spectroscopy, improving the understanding needed for further material …
Characterization And Luminescence Dynamics Of Mgf2:W Ceramics, A.V. Strelkova, V. M. Lisitsyn, L. A. Lisitsyna, T.A. Koketai, D. A. Mussakhanov, Zh.T. Karipbayev, A. M. Zhunusbekov
Characterization And Luminescence Dynamics Of Mgf2:W Ceramics, A.V. Strelkova, V. M. Lisitsyn, L. A. Lisitsyna, T.A. Koketai, D. A. Mussakhanov, Zh.T. Karipbayev, A. M. Zhunusbekov
Eurasian Journal of Physics and Functional Materials
This study delves into the synthesis and characterization of luminescent ceramics based on tungstenactivated magnesium fluoride (MgF2) complemented with varying concentrations of lithium hydroxide (LiOH). Utilizing a distinctive sintering process conducted in an open-air milieu under robust radiation conditions, we successfully synthesized a series of tungsten-activated ceramics. Study revealed that the resultant ceramics prominently display luminescent properties, which can be excited by UV radiation in the spectrum of 200-300 nm, as well as by high-energy electron fluxes. The spectral characteristics of these ceramics, in terms of band position, half-width, and excitation spectra, are strikingly analogous to those observed …
Designing Noncentrosymmetric Multifunctional Materials, Ebube Oyeka
Designing Noncentrosymmetric Multifunctional Materials, Ebube Oyeka
All Dissertations
Noncentrosymmetric (NCS) materials with crystal lattices lacking spatial inversion symmetry display a wide range of exciting functionalities. This dissertation covers two classes of functional NCS materials: magnetic skyrmion-host compounds and multifunctional materials. Magnetic skyrmion and multifunctional materials combining optical and magnetic responses are providing avenues for developing and optimizing the performance of electronic devices that can have uses in memory storage, laser technology, medicine, sensors, etc. The formation of skyrmions is driven by asymmetric Dzyaloshinskii–Moriya (DM) interaction facilitated by broken spatial inversion symmetry and large spin-orbit coupling (SOC), while multiple functionalities arise when spin carriers and optical chromophores are optimally …
Luminescent Properties Of Baxmg(2−X)F4:W Ceramics, T.A. Koketai, A.V. Strelkova, A.M. Zhunusbekov, Zh.T. Karipbayev, L.A. Lisitsyna, A.M. Chakin
Luminescent Properties Of Baxmg(2−X)F4:W Ceramics, T.A. Koketai, A.V. Strelkova, A.M. Zhunusbekov, Zh.T. Karipbayev, L.A. Lisitsyna, A.M. Chakin
Eurasian Journal of Physics and Functional Materials
Ceramics based on alkaline earth metal fluorides activated by tungsten has been obtained by radiation synthesis. The synthesis was realized by direct action on the mixture with an activator of a powerful flow of high-energy electrons without the use of any additives to facilitate the synthesis. It has been established that the resulting ceramics have luminescent properties characteristic of tungsten-activated materials based on metal fluorides.
Optical Studies Of Wide Bandgap Photonic Materials, Nikesh Maharjan
Optical Studies Of Wide Bandgap Photonic Materials, Nikesh Maharjan
Dissertations, Theses, and Capstone Projects
In this dissertation work, optical properties of wide bandgap materials such as hexagonal Boron Nitride (h-BN) and Zinc Oxide (ZnO) have been studied. Deep UV photoluminescence spectroscopy was employed to study the optical properties of bulk h-BN and powder crystals using a laser of wavelength 200 nm, which is the fourth harmonic of Ti:Sapphire laser as excitation source. The properties and chemical compositions of annealed and unannealed bulk h-BN were investigated. The PL spectra from h-BN samples annealed at 900 ºC in ambient air, had strong phonon assisted band edge emissions along with a sharp atomic-like emission line at 4.09 …
Strain-Enhanced Coherent Exciton-Polaron States In 1d Phthalocyanine Crystalline Thin Films, Libin Liang
Strain-Enhanced Coherent Exciton-Polaron States In 1d Phthalocyanine Crystalline Thin Films, Libin Liang
Graduate College Dissertations and Theses
Organic semiconductors are at the forefront of materials research, due to their desired electric and mechanical properties. They offer the unique opportunity to modify material properties during synthesis process, opening an avenue to the development of novel flexible and wearable electronic and photonic devices.Molecular excitons are of importance in organic semiconductor properties. While majority of research studies are centered on achieving good control of amorphous or polycrystalline thin film properties, the static disorder effect leads to poor device performance when compared to inorganic semiconductors with superior crystalline ordering. On the other hand, the macroscopic molecular long-range ordering can enhance device …
Electronic Structure Of Early Transition Metal Complexes Supported By Pyridine Polypyrrolide Ligands, Dylan Connor Leary
Electronic Structure Of Early Transition Metal Complexes Supported By Pyridine Polypyrrolide Ligands, Dylan Connor Leary
Graduate Theses, Dissertations, and Problem Reports
A thorough study of photoluminescent molecules involving the pyridine polypyrrole(ide) ligand platform has been conducted. A detailed analysis on speciation of the proligand H2(MesPDPPh) (H2MesPDPPh = 2,6-bis(5-mesityl-3-phenyl-1H-pyrrol-2-yl)-pyridine) and its dilithium salt Li2(MesPDPPh) revealed temperature- and solvent-dependent effects. These molecules, along with the hydrochloric acid adduct [H3(MesPDPPh)]Cl were found to exhibit short-lived photoluminescence in both tetrahydrofuran and benzene solution. These findings confirm the hypothesis that heavy-atom involvement is crucial for the favorable photophysical properties observed for the Zr(PDP)2 …
Photoluminescence Spectra Of Silicon Doped With Cadmium, N A. Sultanov, E T. Rakhimov, Z Mirzajonov, F T. Yusupov
Photoluminescence Spectra Of Silicon Doped With Cadmium, N A. Sultanov, E T. Rakhimov, Z Mirzajonov, F T. Yusupov
Scientific-technical journal
Cadmium and zinc, as transition metals, are deep-level impurities (DL) and have a significant effect on the electrical, photoelectric, recombination, and other properties of semiconductor crystals.This paper presents the results of experimental studies of the optical and electrical properties of silicon crystals containing impurity atoms of cadmium and zinc using DLTS and low-temperature photoluminescence (PL).
Fundamental Transport Properties In Silicon Quantum Structures, Nazban M. Darukhanawalla
Fundamental Transport Properties In Silicon Quantum Structures, Nazban M. Darukhanawalla
Electronic Thesis and Dissertation Repository
In the field of silicon photonics, there is an effort to bridge the gap between electrical and optical signals on a single platform, creating a need for Si-based light sources. In this project, Si quantum structures – Si quantum wells and quantum dots in SiO2 were fabricated via solid state precipitation methods. Their properties were studied using X-ray photoelectron spectroscopy, photoluminescence and I-V measurements. Rutherford backscattering spectroscopy was used for depth analysis in monitoring the Si distribution. Different electrical transport mechanisms were explored to understand how an ensemble of silicon QD’s or a silicon quantum well behaves in an SiO2 …
Аn Optical Study Of Strain Relaxation And Interdiffusion In Znse/Zncdse Quantum Wells Modified By Γ-Irradiation, Muratbay B. Sharibaev, Kanatbay A. Ismailov, Ibrohim N. Karimov, Murodjon Z. Nosirov
Аn Optical Study Of Strain Relaxation And Interdiffusion In Znse/Zncdse Quantum Wells Modified By Γ-Irradiation, Muratbay B. Sharibaev, Kanatbay A. Ismailov, Ibrohim N. Karimov, Murodjon Z. Nosirov
Scientific Bulletin. Physical and Mathematical Research
If we turn to the literature data, it is known that the degradation of CdZnTe / ZnTe and CdZnSe /ZnSe quantum wells and usually includes two types of processes: (i) fast (as called dynamic, by analogy with the degradation of heterostructures based on A3B5 materials) - germination and propagation of extended defects from a GaAs substrate. This process in CdZnSe / ZnSe is slowed down by various technological methods (treatment of a substrate in sulfur; reduction of a damaged layer in a GaAs substrate; deposition of a GaAs epitaxial buffer layer; use of the concept of compensation of bipolar stresses; …
Optical Properties Of Ultrathin In(Ga)As/Gaas And In(Ga)N/Gan Quantum Wells, Yurii Maidaniuk
Optical Properties Of Ultrathin In(Ga)As/Gaas And In(Ga)N/Gan Quantum Wells, Yurii Maidaniuk
Graduate Theses and Dissertations
Recently, structures based on ultrathin quantum wells (QWs) began to play a critical role in modern devices, such as lasers, solar cells, infrared photodetectors, and light-emitting diodes. However, due to the lack of understanding of the formation mechanism of ultrathin QWs during the capping process, scientists and engineers cannot fully explore the potential of such structures. This study aims to investigate how structural parameters of ultrathin QWs affect their emission properties by conducting a systematic analysis of the optical properties of In(Ga)As/GaAs and In(Ga)N/GaN ultrathin QWs. Specifically, the analysis involved photoluminescence measurements combined with effective bandgap simulation, x-ray diffraction, and …
Laser-Induced Modifications In Two-Dimensional Materials, Tariq Afaneh
Laser-Induced Modifications In Two-Dimensional Materials, Tariq Afaneh
USF Tampa Graduate Theses and Dissertations
Atomically thin two-dimensional (2D) materials have attracted a growing interest in the lastdecade from the fundamental point of view as well as their potential applications in functional devices. Due to their high surface-to-volume ratio, the physical properties of 2D materials are very sensitive to the environmental factor such as surrounding media and illumination conditions (e.g. light-mater interaction). In the first part of this dissertation I will present recent advances in developing laser-assisted methods to tune the physical properties of 2D transition metal dichalcogenides (TMDs). We demonstrate laser-assisted chemical modification ultrathin TMDs, locally replacing selenium by sulfur atoms. The photo-conversion process …
Si Nanocrystal Synthesis Via Double Implantation And Variable Implantation, James M. Gaudet
Si Nanocrystal Synthesis Via Double Implantation And Variable Implantation, James M. Gaudet
Electronic Thesis and Dissertation Repository
Silicon (Si) nanocrystals (nc) precipitated from silicon-implanted silicon oxide (SiO2) are of interest as a novel light source for illumination, biomedical applications, optical computing, etc. They have some advantages over conventional III-V compound semiconductor nanocrystals produced by colloidal synthesis. They are compatible with Si/SiO2 based semiconductor processing, are stable, non-toxic at point of synthesis and consumption, and their luminescence falls with the infrared transmission window of biological materials. Unfortunately, synthesis of Si-nc embedded SiO2 is uneconomical and is not as amenable to precise control of the size distribution of nanocrystals as is the case for III-V …
Luminescence Emission In A Nanocrystal Doped By A Transition Metal Impurity, George Chappell Jr.
Luminescence Emission In A Nanocrystal Doped By A Transition Metal Impurity, George Chappell Jr.
Theses, Dissertations and Capstones
In this thesis we consider the structure of magnetic ion centers with 3d-electrons in quantum dots under the effects of Coulomb and exchange interaction between the 3d-electrons of the impurity centers and the confined electrons (or holes) existing inside the nanocrystals. In particular, we are interested how this interaction changes the photoluminescence properties of those materials. We will make use of representation theory and the symmetry of the crystal structure to find the orthonormal wave functions that make up the wave functions of the outer, 3d-electrons inside our dot. The Coulomb and exchange interaction …
Definition Of Extended Structural Defects In Epitaxial Films Of Znteg‘Gaas Grown By Mbe, Muratbay B. Sharibaev, Kanatbay A. Ismailov, Ibrohim N. Karimov, Murodjon Z. Nosirov
Definition Of Extended Structural Defects In Epitaxial Films Of Znteg‘Gaas Grown By Mbe, Muratbay B. Sharibaev, Kanatbay A. Ismailov, Ibrohim N. Karimov, Murodjon Z. Nosirov
Scientific Bulletin. Physical and Mathematical Research
The last three decades of the development of solid state physics are characterized by the fact that the main objects of research are increasingly not massive crystals, but thin films, multilayer thin-film systems, conducting filaments and crystallites of small size. Epitaxial films are grown on a substrate of a single crystal of the same or another material. In the first case, the epitaxial layer with the correct technology becomes a natural extension of the substrate. Epitaxial film can be doped with various impurities. To introduce an alloying admixture into the epitaxial film, three methods are used. According to the first …
Deep Donors And Acceptors In Β-Ga2O3 Crystals: Determination Of The Fe2+/3+ Level By A Noncontact Method, Christopher A. Lenyk, Trevor A . Gustafson, Larry E. Halliburton, Nancy C. Giles
Deep Donors And Acceptors In Β-Ga2O3 Crystals: Determination Of The Fe2+/3+ Level By A Noncontact Method, Christopher A. Lenyk, Trevor A . Gustafson, Larry E. Halliburton, Nancy C. Giles
Faculty Publications
Electron paramagnetic resonance (EPR), infrared absorption, and thermoluminescence (TL) are used to determine the Fe2+/3+ level in Fe-doped β-Ga2O3 crystals. With these noncontact spectroscopy methods, a value of 0.84 ± 0.05 eV below the conduction band is obtained for this level. Our results clearly establish that the E2 level observed in deep level transient spectroscopy (DLTS) experiments is due to the thermal release of electrons from Fe2+ ions. The crystals used in this investigation were grown by the Czochralski method and contained large concentrations of Fe acceptors and Ir donors, and trace amounts of Cr …
Near-Field And Far-Field Microscopic And Spectroscopic Characterizations Of Coupled Plasmonic, Excitonic And Polymeric Materials, Chih-Feng Wang
Near-Field And Far-Field Microscopic And Spectroscopic Characterizations Of Coupled Plasmonic, Excitonic And Polymeric Materials, Chih-Feng Wang
Optical Science and Engineering ETDs
The properties of localized surface plasmons (LSP) have been broadly utilized for chemical sensing, surface enhanced Raman spectroscopy, biomedical imaging and photothermal treatments. By exploiting well-established plasmonic effects, the spectroscopic investigation of intriguing quantum phenomena, such as excitonic interband and intersubband (ISB) transitions in semiconductor heterostructures, was examined and extended in both far- and near-field optical measurements. For far-field characterization, we used colloidal plasmonic Au nanorods (AuNRs) to increase the quantum efficiency of InGaAs/GaAs single quantum well. By analyzing the temperature-dependent photoluminescence enhancement as a function of GaAs capping layer thickness, we attributed the mechanism of the LSP enhancement to …
Tip-Enhanced Nano-Optical Imaging Of Superacid Treated Bilayer Mos2-Ws2 2d Lateral Heterostructures, Amala Dixit
Tip-Enhanced Nano-Optical Imaging Of Superacid Treated Bilayer Mos2-Ws2 2d Lateral Heterostructures, Amala Dixit
USF Tampa Graduate Theses and Dissertations
Nanoscale optical characterization of two-dimensional (2D) materials and heterostructures is important for the design of novel optoelectronic flexible nano-devices. Nano-optical photoluminescence (PL) and Raman imaging of bilayer 2D materials has been a challenging problem due to weak signals. The exciton-dominated light emission of two-dimensional (2D) transition metal dichalcogenide (TMDC) materials is affected by the formation of defects and doping states. Previous studies have shown that chemical treatment modifies the defect and doping states of chemical vapor deposition (CVD)-grown monolayers of MoS2 and WS2, which provides a promising possibility for engineering the optoelectronic properties of these 2D TMDCs. …
Probing Quantized Excitations And Many-Body Correlations In Transition Metal Dichalcogenides With Optical Spectroscopy, Shao-Yu Chen
Probing Quantized Excitations And Many-Body Correlations In Transition Metal Dichalcogenides With Optical Spectroscopy, Shao-Yu Chen
Doctoral Dissertations
Layered transition metal dichalcogenides (TMDCs) have attracted great interests in recent years due to their physical properties manifested in different polytypes: Hexagonal(H)-TMDC,which is semiconducting, exhibits strong Coulomb interaction and intriguing valleytronic properties; distorted octahedral(T’)-TMDC,which is semi-metallic, is predicted to exhibit rich nontrivial topological physics. In this dissertation,we employ the polarization-resolved micron-Raman/PL spectroscopy to investigate the optical properties of the atomic layer of several polytypes of TMDC. In the first part for polarization-resolved Raman spectroscopy, we study the lattice vibration of both H and T’-TMDC, providing a thorough understanding of the polymorphism of TMDCs. We demonstrate that Raman spectroscopy is a …
Some Radiation Effects In Ii-Vi Quantum Dots, M. B. Sharibaev, Q. A. Ismailov
Some Radiation Effects In Ii-Vi Quantum Dots, M. B. Sharibaev, Q. A. Ismailov
Eurasian Journal of Physics and Functional Materials
The effect of electron irradiation (E=0.6-1.8 MeV) on the optical characteristics (photoluminescence, PL) of CdTe/ZnTe structures with quantum dots, QDs, was investigated in the temperature range from 4.2 to 250 K. The data on the influence of irradiation on the temperature dependence of PL intensity, energy position and PL line width, W, from QDs were obtained. The narrowing of PL band and the blue shift of the QD peak position are explained by quenching of the low energy component connected with larger QDs. A slight decrease in PL intensity for both QDs and the buffer ZnTe layer as well as …
Plasmonic Enhancement Of Photoluminescence And Photobrightening In Cdse Quantum Dots, David Alan French
Plasmonic Enhancement Of Photoluminescence And Photobrightening In Cdse Quantum Dots, David Alan French
Graduate Theses and Dissertations
Quantum dots are gaining recognition not just in the physics and chemistry community, but in the public eye as well. Quantum dot technologies are now being used in sensors, detectors, and even television displays. By exciting quantum dots with light or electricity, they can be made to emit light, and by altering the quantum dot characteristics the wavelength can be finely tuned. The light emitted can be also be made more intense by an increase in the excitation energy. The excitation light can be increased via plasmonic enhancement, leading to increased luminescence. Aside from the relatively steady-state response, quantum dots …
Spectra Of One – And Two Photon Excited Luminescence Of Medical Drugsin Photon Traps, A.K. Kubanov, D.I. Semenov
Spectra Of One – And Two Photon Excited Luminescence Of Medical Drugsin Photon Traps, A.K. Kubanov, D.I. Semenov
Scientific Journal of Samarkand University
A technique for studying the photoluminescence spectra of pharmaceuticals (analgin, paracetamol) was developed for single- and two-photon excitation by a pulse-periodic laser. The technique is based on the fiber-optic recording of photoluminescence spectra using a small-size spectrometer, quartz light guides, and mini cavity cuvettes, which makes it possible to compare the analyzed spectrum with the spectrum of the reference substance.
Combined Spectroscopic And Scanning Probe Studies Of Electronic Interactions In Nanostructured 1d And 2d Semiconductors, Peijian Wang
Combined Spectroscopic And Scanning Probe Studies Of Electronic Interactions In Nanostructured 1d And 2d Semiconductors, Peijian Wang
Doctoral Dissertations
This dissertation includes the exploration about the following research questions: 1. What is the correlation between the work function and ground state interactions in organic semiconductor assemblies? 2. How do non-covalent chemical doping tune the work function in MoS2? 3. Are there surface charges in the Aluminum doped ZnO nanocrystals (AZO) and what's the evolution of the surface charges and polarizabilities from undoped AZO to doped AZO? 4. How is the homogeneity like during doping in the organic thermoelectric materials? The techniques we employed in the research is the spatially registered Kelvin Probe Force Microscopy and Photoluminescence spectroscopy …
Near Bandgap Two-Photon Excited Luminescence Of Inas Quantum Dots, Xian Hu
Near Bandgap Two-Photon Excited Luminescence Of Inas Quantum Dots, Xian Hu
Graduate Theses and Dissertations
Semiconductor quantum dots (QDs) confine carriers in three dimensions, resulting in atomic-like energy levels as well as size-dependent electrical and optical properties. Self-assembled III-V QD is one of the most studied semiconductor QDs thanks to their well-established fabrication techniques and versatile optical properties. This dissertation presents the photoluminescence (PL) study of the InAs/GaAs QDs with both above bandgap continuous-wave excitation (one-photon excitation) and below-bandgap pulse excitation (two-photon excitation). Samples of ensemble QDs, single QD (SQD), and QDs in a micro-cavity, all grown by molecular beam epitaxy, are used in this study. Morphology of these samples was examined using atomic force …
Copper-Doped Lithium Triborate (Lib3o5) Crystals: A Photoluminescence, Thermoluminescence, And Electron Paramagnetic Resonance Study, Brant E. Kananen, John W. Mcclory, Nancy C. Giles, Larry E. Halliburton
Copper-Doped Lithium Triborate (Lib3o5) Crystals: A Photoluminescence, Thermoluminescence, And Electron Paramagnetic Resonance Study, Brant E. Kananen, John W. Mcclory, Nancy C. Giles, Larry E. Halliburton
Faculty Publications
When doped with copper ions, lithium borate materials are candidates for use in radiation dosimeters. Copper-doped lithium tetraborate (Li2B4O7) crystals have been widely studied, but little is known thus far about copper ions in lithium triborate (LiB3O5) crystals. In the present investigation, Cu+ ions (3d10) were diffused into an undoped LiB3O5 crystal at high temperature. These ions occupy both Li+ and interstitial positions in the crystal. A photoluminescence (PL) band peaking near 387 nm and a photoluminescence excitation (PLE) band peaking near 273 nm verify that a portion of these Cu+ ions are located at regular Li+ sites. After an …
Photoluminescence From Gan Co-Doped With C And Si, Mykhailo Vorobiov
Photoluminescence From Gan Co-Doped With C And Si, Mykhailo Vorobiov
Theses and Dissertations
This thesis devoted to the experimental studies of yellow and blue luminescence (YL and BL relatively) bands in Gallium Nitride samples doped with C and Si. The band BLC was at first observed in the steady-state photoluminescence spectrum under high excitation intensities and discerned from BL1 and BL2 bands appearing in the same region of the spectrum. Using the time-resolved photoluminescence spectrum, we were able to determine the shape of the BLC and its position at 2.87 eV. Internal quantum efficiency of the YL band was estimated to be 90\%. The hole capture coefficient of the BLC …
Determination Of The Energy Band Gap Of Bi₂Se₃, G. Martinez, B. A. Piot, M. Hakl, M. Potemski, Yew San Hor
Determination Of The Energy Band Gap Of Bi₂Se₃, G. Martinez, B. A. Piot, M. Hakl, M. Potemski, Yew San Hor
Physics Faculty Research & Creative Works
Despite intensive investigations of Bi2Se3 in past few years, the size and nature of the bulk energy band gap of this well-known 3D topological insulator still remain unclear. Here we report on a combined magneto-transport, photoluminescence and infrared transmission study of Bi2Se3, which unambiguously shows that the energy band gap of this material is direct and reaches Eg = (220 ± 5) meV at low temperatures.
A Transfer Matrix Approach To Aid In The Design And Optimization Of Hybrid Advanced Passive Structures For Enhancing Photovoltaic Efficiency, James Walshe, Sarah Mccormack, Hind Ahmed, John Doran
A Transfer Matrix Approach To Aid In The Design And Optimization Of Hybrid Advanced Passive Structures For Enhancing Photovoltaic Efficiency, James Walshe, Sarah Mccormack, Hind Ahmed, John Doran
Conference Papers
The addition of a luminescent down-shifting (LDS) layer directly onto a photovoltaic (PV) cell introduces additional loss mechanisms within the system. The combination of non-ideal photo-luminescent materials encapsulated within a limited range of viable host materials, with the increased reflection losses arising from the newly created interface represent losses which must be overcome for LDS to offer an enhancement to the underlying cells efficiency. Exploiting the interaction between the highly enhanced electric fields established close to a metal nanoparticles (MNP’s) surface is one route aimed at mitigating the poor optical properties of the luminophore-host combinations available. Alternative approaches, aimed at …