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Full-Text Articles in Engineering
Experimental And Theoretical Study Of Polarization-Dependent Optical Transitions In Inas Quantum Dots At Telecommunication-Wavelengths (1300-1500 Nm), Muhammad Usman, Susannah Heck, Edmund Clarke, Peter Spencer, Hoon Ryu, Ray Murray, Gerhard Klimeck
Experimental And Theoretical Study Of Polarization-Dependent Optical Transitions In Inas Quantum Dots At Telecommunication-Wavelengths (1300-1500 Nm), Muhammad Usman, Susannah Heck, Edmund Clarke, Peter Spencer, Hoon Ryu, Ray Murray, Gerhard Klimeck
Birck and NCN Publications
observed, in contrast to recent reports for single QDJOURNAL OF APPLIED PHYSICS 109, 104510 (2011)
The design of some optical devices, such as semiconductor optical amplifiers for telecommunication applications, requires polarization-insensitive optical emission at long wavelengths (1300–1550 nm). Self-assembled InAs/GaAs quantum dots (QDs) typically exhibit ground state optical emissions at wavelengths shorter than 1300 nm with highly polarization-sensitive characteristics, although this can be modified by the use of low growth rates, the incorporation of strain-reducing capping layers, or the growth of closely-stacked QD layers. Exploiting the strain interactions between closely stacked QD layers also affords greater freedom in the choice …
Tuning Lattice Thermal Conductance By Porosity Control In Ultrascaled Si And Ge Nanowires, Abhijeet Paul, Gerhard Klimeck
Tuning Lattice Thermal Conductance By Porosity Control In Ultrascaled Si And Ge Nanowires, Abhijeet Paul, Gerhard Klimeck
Birck and NCN Publications
Porous nanowires NWs with tunable thermal conductance are examined as a candidate for thermoelectric devices with high efficiency. Thermal conductance l of porous NWs is calculated using the phonon dispersion obtained from a modified valence force field model. Porosity in the NWs break the crystal symmetry leading to the reduction in ballistic l. 100 Si and Ge NWs show similar percentage reductions in l for the same amount of porosity. The model predicts an anisotropic reduction in l in SiNWs, with 111 showing the maximum reduction followed by 100 and 110 for a similar hole radius. The reduction in l …
A Compact Physical Model For Morphology Induced Intrinsic Degradation Of Polymer Based Bulk Heterojunction Solar Cell, Biswajit Ray, Muhammad A. Alam
A Compact Physical Model For Morphology Induced Intrinsic Degradation Of Polymer Based Bulk Heterojunction Solar Cell, Biswajit Ray, Muhammad A. Alam
Birck and NCN Publications
The gradual loss of efficiency during field operation poses a fundamental challenge for economic viability of any solar cell technology. Well known examples include light-induced degradation in Si-based cell (Staebler-Wronski effect), Cu diffusion in thin film (CIGS) cell, hot-spot degradation in series connected modules, etc. Here we develop a compact model for an intrinsic degradation concern for bulk heterojunction type organic photovoltaic (BH-OPV) cells that involve continued (thermal) phase segregation of the donor-acceptor molecules leading to characteristic loss of efficiency and performance. Our approach interprets a number of BH-OPV device degradation measurements within a common framework and suggests/rationalizes intuitive routes …