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Full-Text Articles in Physics
Atomic Force Microscopy Cantilever-Based Nanoindentation: Mechanical Property Measurements At The Nanoscale In Air And Fluid, Ashton E. Enrriques, Sean Howard, Raju Timsina, Nawal K. Khadka, Amber N. Hoover, Allison E. Ray, Ling Ding, Chioma Onwumelu, Stephan Nordeng, Laxman Mainali, Gunes Uzer, Paul H. Davis
Atomic Force Microscopy Cantilever-Based Nanoindentation: Mechanical Property Measurements At The Nanoscale In Air And Fluid, Ashton E. Enrriques, Sean Howard, Raju Timsina, Nawal K. Khadka, Amber N. Hoover, Allison E. Ray, Ling Ding, Chioma Onwumelu, Stephan Nordeng, Laxman Mainali, Gunes Uzer, Paul H. Davis
Physics Faculty Publications and Presentations
An atomic force microscope (AFM) fundamentally measures the interaction between a nanoscale AFM probe tip and the sample surface. If the force applied by the probe tip and its contact area with the sample can be quantified, it is possible to determine the nanoscale mechanical properties (e.g., elastic or Young's modulus) of the surface being probed. A detailed procedure for performing quantitative AFM cantilever-based nanoindentation experiments is provided here, with representative examples of how the technique can be applied to determine the elastic moduli of a wide variety of sample types, ranging from kPa to GPa. These include live mesenchymal …
Kinetic Monte Carlo Simulations Of Quantum Dot Self-Assembly, Matthew Abramson, Hunter J. Coleman, Paul J. Simmonds, Tim P. Schulze, Christian Ratsch
Kinetic Monte Carlo Simulations Of Quantum Dot Self-Assembly, Matthew Abramson, Hunter J. Coleman, Paul J. Simmonds, Tim P. Schulze, Christian Ratsch
Physics Faculty Publications and Presentations
In the Stranski–Krastanov growth mode for heteroepitaxial systems, layer-by-layer growth is followed by the formation and growth of three-dimensional (3D) islands. In this paper, we use a kinetic Monte Carlo method to simulate this growth mode behavior. We present a detailed and systematic investigation into the effects of key model parameters including strain, growth temperature, and deposition rate on this phenomenon. We show that increasing the strain lowers the apparent critical thickness that is defined by the onset of 3D island formation. Similarly, increasing the growth temperature lowers the apparent critical thickness, until intermixing, and the resulting relevance of entropic …
Effect Of As Flux On Inas Submonolayer Quantum Dot Formation For Infrared Photodetectors, K. D. Vallejo, P. J. Simmonds
Effect Of As Flux On Inas Submonolayer Quantum Dot Formation For Infrared Photodetectors, K. D. Vallejo, P. J. Simmonds
Physics Faculty Publications and Presentations
The performance of infrared photodetectors based on submonolayer quantum dots was investigated as a function of the arsenic flux. All the devices showed similar figures of merit and a very high specific detectivity above 1 × 1011 cm Hz1/2/W at 12 K, despite the fact that cross-sectional scanning tunneling microscopy images pointed out a strong reduction in the density of such nanostructures with decreasing arsenic flux. This contrast is a consequence of the small size and low In content of the submonolayer quantum dots that lead to a strong delocalization of the electrons wave function and, therefore, …
Single-Photon Generation From Self-Assembled Gaas/Inalas(111)A Quantum Dots With Ultrasmall Fine-Structure Splitting, Christopher F. Schuck, Robert Boutelle, Kevin Silverman, Galan Moody, Paul J. Simmonds
Single-Photon Generation From Self-Assembled Gaas/Inalas(111)A Quantum Dots With Ultrasmall Fine-Structure Splitting, Christopher F. Schuck, Robert Boutelle, Kevin Silverman, Galan Moody, Paul J. Simmonds
Physics Faculty Publications and Presentations
We present a novel semiconductor single-photon source based on tensile-strained (111)-oriented GaAs/InAlAs quantum dots (QDs) exhibiting ultrasmall exciton fine-structure splitting (FSS) of ≤ 8 µeV. Using low-temperature micro-photoluminescence spectroscopy, we identify the biexciton-exciton radiative cascade from individual QDs, which, combined with small FSS, indicates these self-assembled GaAs(111) QDs are excellent candidates for polarization-entangled photon-pair generation.
Strain-Driven Quantum Dot Self-Assembly By Molecular Beam Epitaxy, Kathryn E. Sautter, Kevin D. Vallejo, Paul J. Simmonds
Strain-Driven Quantum Dot Self-Assembly By Molecular Beam Epitaxy, Kathryn E. Sautter, Kevin D. Vallejo, Paul J. Simmonds
Physics Faculty Publications and Presentations
Research into self-assembled semiconductor quantum dots (QDs) has helped advance numerous optoelectronic applications, ranging from solid-state lighting to photodetectors. By carefully controlling molecular beam epitaxy (MBE) growth parameters, we can readily tune QD light absorption and emission properties to access a broad portion of the electromagnetic spectrum. Although this field is now sufficiently mature that QDs are found in consumer electronics, research efforts continue to expand into new areas. By manipulating MBE growth conditions and exploring new combinations of materials, substrate orientations, and the sign of strain, a wealth of opportunities exist for synthesizing novel QD nanostructures with hitherto unavailable …
Quantum Dot Growth On (111) And (110) Surfaces Using Tensile-Strained Self-Assembly, Paul J. Simmonds
Quantum Dot Growth On (111) And (110) Surfaces Using Tensile-Strained Self-Assembly, Paul J. Simmonds
Physics Faculty Publications and Presentations
The self-assembly of epitaxial quantum dots on (001) surfaces, driven by compressive strain, is a widely used tool in semiconductor optoelectronics. In contrast, the growth of quantum dots on (111) and (110) surfaces has historically been a significant challenge. In most cases the strain relaxes rapidly via dislocation nucleation and glide before quantum dots can form. In this paper, we discuss a method for the reliable and controllable self-assembly of quantum dots on both (111) and (110) surfaces, where tensile strain is now the driving force. By showing that tensile-strained self-assembly is applicable to several material systems, we demonstrate the …