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Full-Text Articles in Physical Sciences and Mathematics
Practicality Of Compensating The Loss In The Plasmonic Waveguides Using Semiconductor Gain Medium, Jacob B. Khurgin, Greg Sun
Practicality Of Compensating The Loss In The Plasmonic Waveguides Using Semiconductor Gain Medium, Jacob B. Khurgin, Greg Sun
Physics Faculty Publications
We consider the issue of compensating the loss in plasmonic waveguides with semiconductor gain material and show that, independent of specific geometry, full loss compensation in plasmonic waveguides with significantly sub-wavelength light confinement (less than λ/4n) requires current density well in excess of 100 kA/cm2. This high current density is attributed to the unavoidable shortening of recombination time caused by the Purcell effect inherent to sub-wavelength confinement. Consequently, an injection-pumped plasmonic laser that is truly sub-wavelength in all three dimensions (“spaser”) would have threshold current densities that are hard to obtain in any conceivable semiconductor device.
Deep Traps In Algan/Gan Heterostructures Studied By Deep Level Transient Spectroscopy: Effect Of Carbon Concentration In Gan Buffer Layers, Z-Q. Fang, B. Claflin, David C. Look, D. S. Green, R. Vetury
Deep Traps In Algan/Gan Heterostructures Studied By Deep Level Transient Spectroscopy: Effect Of Carbon Concentration In Gan Buffer Layers, Z-Q. Fang, B. Claflin, David C. Look, D. S. Green, R. Vetury
Physics Faculty Publications
Electrical properties, including leakage currents, threshold voltages, and deep traps, of AlGaN/GaN heterostructure wafers with different concentrations of carbon in the GaN buffer layer, have been investigated by temperature dependent current-voltage and capacitance-voltage measurements and deep level transient spectroscopy (DLTS), using Schottky barrier diodes (SBDs). It is found that (i) SBDs fabricated on the wafers with GaN buffer layers containing a low concentration of carbon (low-[C] SBD) or a high concentration of carbon (high-[C] SBD) have similar low leakage currents even at 500 K; and (ii) the low-[C] SBD exhibits a larger (negative) threshold voltage than the high-[C] SBD. Detailed …
Impact Of High-Order Surface Plasmon Modes Of Metal Nanoparticles On Enhancement Of Optical Emission, Greg Sun, Jacob B. Khurgin, C. C. Yang
Impact Of High-Order Surface Plasmon Modes Of Metal Nanoparticles On Enhancement Of Optical Emission, Greg Sun, Jacob B. Khurgin, C. C. Yang
Physics Faculty Publications
We consider the impact of high-order surface plasmon modes supported by the metal nanoparticles on the efficiency enhancement of optical emission. Using the example of Au nanosphere embedded in the GaN dielectric, we show that for an emitter with certain original radiative efficiency, placing the emitter too close to the metal sphere does not always produce additional enhancement. Thus our model provides analytical treatment of the luminescence quenching and can be used to optimize both nanoparticle size and its separation from the emitter to yield maximum enhancement.
Enhancement Of Light Absorption In A Quantum Well By Surface Plasmon Polariton, Jacob B. Khurgin, Greg Sun
Enhancement Of Light Absorption In A Quantum Well By Surface Plasmon Polariton, Jacob B. Khurgin, Greg Sun
Physics Faculty Publications
We investigate analytically the degree to which the absorption of light in a single quantum well can be enhanced in the proximity of a structured metallic surface and show that the wavelength at which the maximum enhancement of about one order of magnitude is attained depends on metal loss and the initial absorption in a quantum well.
Practical Enhancement Of Photoluminescence By Metal Nanoparticles, Greg Sun, Jacob B. Khurgin, R. A. Soref
Practical Enhancement Of Photoluminescence By Metal Nanoparticles, Greg Sun, Jacob B. Khurgin, R. A. Soref
Physics Faculty Publications
We develop a simple yet rigorous theory of the photoluminescence (PL) enhancement in the vicinity of metal nanoparticles. The enhancement takes place during both optical excitation and emission. The strong dependence on the nanoparticle size enables optimization for maximum PL efficiency. Using the example of InGaN quantum dots (QDs) positioned near Ag nanospheres embedded in GaN, we show that strong enhancement can be obtained only for those QDs, atoms, or molecules that are originally inefficient in absorbing as well as in emitting optical energy. We then discuss practical implications for sensor technology.
Electroluminescence Efficiency Enhancement Using Metal Nanoparticles, Jacob B. Khurgin, Greg Sun, R. A. Soref
Electroluminescence Efficiency Enhancement Using Metal Nanoparticles, Jacob B. Khurgin, Greg Sun, R. A. Soref
Physics Faculty Publications
We apply the “effective mode volume” theory to evaluate enhancement of the electroluminescence efficiency of semiconductor emitters placed in the vicinity of isolated metal nanoparticles and their arrays. Using the example of an InGaN/GaN quantum-well active region positioned in close proximity to Ag nanospheres, we show that while the enhancement due to isolated metal nanoparticles is large, only modest enhancement can be obtained with ordered array of those particles. We further conclude that random assembly of isolated particles holds an advantage over the ordered arrays for light emitting devices of finite area.
Practicable Enhancement Of Spontaneous Emission Using Surface Plasmons, Greg Sun, Jacob B. Khurgin, Richard A. Soref
Practicable Enhancement Of Spontaneous Emission Using Surface Plasmons, Greg Sun, Jacob B. Khurgin, Richard A. Soref
Physics Faculty Publications
The authors develop a rigorous theory of the enhancement of spontaneous emission from a light emitting device via coupling the radiant energy in and out of surface plasmon polaritons (SPPs) on the metal-dielectric interface. Using the GaN/Ag system as an example, the authors show that using SPP pays off only for emitters that have a low luminescence efficiency.
Nonlinear All-Optical Gan/Algan Multi-Quantum-Well Devices For 100 Gb/S Applications At Λ = 1.55 Μm, Greg Sun, Jacob B. Khurgin, Richard A. Soref
Nonlinear All-Optical Gan/Algan Multi-Quantum-Well Devices For 100 Gb/S Applications At Λ = 1.55 Μm, Greg Sun, Jacob B. Khurgin, Richard A. Soref
Physics Faculty Publications
Using quantum-mechanical analysis, a strain-balanced stack of coupled GaN/AlGaNquantum wells has been engineered for bandwidth-optimized all-optical switching at low switching powers. Intersubband transitions between three conduction subbands provide the basis for the large, fast, nonlinear optical response. Optimized performance for a given symbol rate is obtained by engineering the response time and nonlinear phase shift.
Electron-Irradiation-Induced Deep Level In N-Type Gan, Z-Q. Fang, Joseph W. Hemsky, David C. Look, M. P. Mack
Electron-Irradiation-Induced Deep Level In N-Type Gan, Z-Q. Fang, Joseph W. Hemsky, David C. Look, M. P. Mack
Physics Faculty Publications
Deep-level transient spectroscopy measurements of n-type GaN epitaxial layers irradiated with 1-MeV electrons reveal an irradiation-induced electron trap at EC−0.18 eV. The production rate is approximately 0.2 cm−1, lower than the rate of 1 cm−1 found for the N vacancy by Hall-effect studies. The defect trap cannot be firmly identified at this time. ©1998 American Institute of Physics.
Optical Properties Of Gan Grown On Zno By Reactive Molecular Beam Epitaxy, F. Hamdani, A. Botchkarev, W. Kim, H. Morkoç, M. Yeadon, J. M. Gibson, S.-C. Y. Tsen, David J. Smith, Donald C. Reynolds, David C. Look, K. R. Evans, Cole W. Litton, William C. Mitchel, P. Hemenger
Optical Properties Of Gan Grown On Zno By Reactive Molecular Beam Epitaxy, F. Hamdani, A. Botchkarev, W. Kim, H. Morkoç, M. Yeadon, J. M. Gibson, S.-C. Y. Tsen, David J. Smith, Donald C. Reynolds, David C. Look, K. R. Evans, Cole W. Litton, William C. Mitchel, P. Hemenger
Physics Faculty Publications
High quality wurtzite GaN epilayers have been grown on ZnO(0001) substrates by reactive molecular beam epitaxy. Photoluminescence and reflectivity measurements point to high quality presumably due to the near match of both the crystal lattice parameter and the stacking order between GaN and ZnO. In addition, the good films lack the characteristic yellow photoluminescence band. Any misorientation of the GaN epilayer planes with respect to the ZnO substrate is not detectable with polarized reflectivity. The x-ray double crystal diffraction measurements indicate this misorientation is much smaller than those for GaN epilayers on SiC and Al2O3 . © …