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Full-Text Articles in Physics

Dreams Of Molecular Beams: Indium Gallium Arsenide Tensile-Strained Quantum Dots And Advances Towards Dynamic Quantum Dots (Moleculare Radiorum Somnia: Indii Gallii Arsenicus Tensa Quanta Puncta Et Ad Dinamicae Quantae Puntae Progressus), Kevin Daniel Vallejo Dec 2021

Dreams Of Molecular Beams: Indium Gallium Arsenide Tensile-Strained Quantum Dots And Advances Towards Dynamic Quantum Dots (Moleculare Radiorum Somnia: Indii Gallii Arsenicus Tensa Quanta Puncta Et Ad Dinamicae Quantae Puntae Progressus), Kevin Daniel Vallejo

Boise State University Theses and Dissertations

Through the operation of a molecular beam epitaxy (MBE) machine, I worked on developing the homoepitaxy of high quality InAs with a (111)A crystallographic orientation. By tuning substrate temperature, we obtained a transition from a 2D island growth mode to step- ow growth. Optimized MBE parameters (substrate temperature = 500 °C, growth rate = 0.12 ML/s and V/III ratio ⩾ 40) lead to growth of extremely smooth InAs(111)A films, free from hillocks and other 3D surface imperfections. We see a correlation between InAs surface smoothness and optical quality, as measured by photoluminescence spectroscopy. This work establishes InAs(111)A as a platform …


Defect-Free Plastic Deformation Through Dimensionality Reduction And Self-Annihilation Of Topological Defects In Crystalline Solids, Yipeng Gao, Yongfeng Zhang, Larry K. Aagesen, Jianguo Yu, Min Long, Yunzhi Wang Feb 2020

Defect-Free Plastic Deformation Through Dimensionality Reduction And Self-Annihilation Of Topological Defects In Crystalline Solids, Yipeng Gao, Yongfeng Zhang, Larry K. Aagesen, Jianguo Yu, Min Long, Yunzhi Wang

Computer Science Faculty Publications and Presentations

As a signature of symmetry-breaking processes, the generation and annihilation of topological defects (domain walls, strings, etc.) are of great interest in condensed matter physics and cosmology. Here we propose a distinctive self-organization process through phase transitions, in which all the generated topological defects are dimensionality reduced and self-annihilated. In crystalline solids, such a unique mechanism allows a perfect single crystal after plastic deformation, which originates from the coupling of different types of broken symmetries.


Anomalous Stranski-Krastanov Growth Of (111)-Oriented Quantum Dots With Tunable Wetting Layer Thickness, Christopher F. Schuck, Simon K. Roy, Trent Garrett, Paul J. Simmonds Dec 2019

Anomalous Stranski-Krastanov Growth Of (111)-Oriented Quantum Dots With Tunable Wetting Layer Thickness, Christopher F. Schuck, Simon K. Roy, Trent Garrett, Paul J. Simmonds

Materials Science and Engineering Faculty Publications and Presentations

Driven by tensile strain, GaAs quantum dots (QDs) self-assemble on In0.52Al0.48As(111)A surfaces lattice-matched to InP substrates. In this study, we show that the tensile-strained self-assembly process for these GaAs(111)A QDs unexpectedly deviates from the well-known Stranski-Krastanov (SK) growth mode. Traditionally, QDs formed via the SK growth mode form on top of a flat wetting layer (WL) whose thickness is fixed. The inability to tune WL thickness has inhibited researchers’ attempts to fully control QD-WL interactions in these hybrid 0D-2D quantum systems. In contrast, using microscopy, spectroscopy, and computational modeling, we demonstrate that for GaAs(111)A QDs, we …


Sex Differences In Lower Limb Biomechanics During A Single-Leg Cut With Body Borne Load, Auralea Carylon Fain May 2018

Sex Differences In Lower Limb Biomechanics During A Single-Leg Cut With Body Borne Load, Auralea Carylon Fain

Boise State University Theses and Dissertations

Introduction: Musculoskeletal injuries are ever-increasing in military personnel, particularly females. These musculoskeletal injuries are attributed to adaptations in lower limb biomechanics while performing routine military tasks, such as a single-leg cut, with the addition of body borne load. However, it is unknown if females and males exhibit similar lower limb biomechanics with the addition of body borne load during these tasks. This study sought to compare the lower limb biomechanical adaptations exhibited by females and males performing a single-leg cut with body borne load. Methods: Eleven females and 17 males had lower limb biomechanics quantified during a single-leg cut with …


Verifying The Implementation Of An Anisotropic Grain Boundary Energy Model In Idaho National Lab’S Marmot, John-Michael H. Bradley, Evan D. Hansen, Jarin C. French, Yongfeng Zhang (Mentor) Jan 2017

Verifying The Implementation Of An Anisotropic Grain Boundary Energy Model In Idaho National Lab’S Marmot, John-Michael H. Bradley, Evan D. Hansen, Jarin C. French, Yongfeng Zhang (Mentor)

Idaho Conference on Undergraduate Research

This work aims to verify the correct implementation of an anisotropic grain boundary (GB) energy model for face-centered cubic (FCC) and fluorite materials in Idaho National Laboratory’s phase field fuel performance code MARMOT. The model was recently implemented in MARMOT with the purpose of enabling higher fidelity simulations of UO2 nuclear fuels. As part of verification, tests were performed to measure the energy dependence on misorientation of high symmetry GBs in an FCC metal (Cu). The energies of the [100], [110], and [111] twist boundaries result as predicted, as do the energies of the [111] symmetric tilt boundaries. However, …


Influence Of Microstructure On The Propagation Of Fatigue Cracks In Inconel 617, Benjiman Michael Albiston Jul 2013

Influence Of Microstructure On The Propagation Of Fatigue Cracks In Inconel 617, Benjiman Michael Albiston

Boise State University Theses and Dissertations

Inconel 617 is a candidate material for use in the intermediate heat exchanger of the Next Generation Nuclear Plant. Because of the high temperatures and the fluctuations in stress and temperature, the fatigue behavior of the material is important to understand. The goal of this study was to determine the influences of the microstructure during fatigue crack propagation. For this investigation, Inconel 617 compact tension samples, fatigue tested by Julian Benz at the Idaho National Laboratory, were obtained. The testing conditions included two environments at 650 °C (lab air and impure-He) and varied testing parameters including: loading waveform (triangular, trapezoidal), …


Quantum Transport In In0.75Ga0.25As Quantum Wires, P. J. Simmonds, F. Sfigakis, H. E. Beere, D. A. Ritchie, M. Pepper, D. Anderson, G. A.C. Jones Apr 2008

Quantum Transport In In0.75Ga0.25As Quantum Wires, P. J. Simmonds, F. Sfigakis, H. E. Beere, D. A. Ritchie, M. Pepper, D. Anderson, G. A.C. Jones

Paul J. Simmonds

In addition to quantized conductance plateaus at integer multiples of 2e2/h, the differential conductance G=dI/dV shows plateaus at 0.25(2e2/h) and 0.75(2e2/h) under applied source-drain bias in In0.75Ga0.25As quantum wires defined by insulated split gates. This observation is consistent with a spin-gap model for the 0.7 structure. Using a tilted magnetic field to induce Landau level crossings, the g factor was measured to be ~9 by the coincidence method. This material, with a mobility of 1.8×105 cm …


Growth-Temperature Optimization For Low Carrier-Density In0.75Ga0.25As-Based High Electron Mobility Transistors On Inp, Paul J. Simmonds, H. E. Beere, D. A. Ritchie, S. N. Holmes Oct 2007

Growth-Temperature Optimization For Low Carrier-Density In0.75Ga0.25As-Based High Electron Mobility Transistors On Inp, Paul J. Simmonds, H. E. Beere, D. A. Ritchie, S. N. Holmes

Paul J. Simmonds

Two-dimensional electron gases (2DEGs) were formed in undoped In0.75Al0.25As / In0.75Ga0.25As / In0.75Al0.25As quantum wells. The optimal growth temperature for this structure is 410°C, with peak 2DEG electron mobility and density values of μ = 221000 cm2/V s and n = 1.36 × 1011 cm−2 at 1.5 K. This electron mobility is equal to the highest previously published for these undoped structures but with a factor of 2 reduction in n. This has been achieved through the use of a significantly thinner InAlAs …


Quantum Dot Resonant Tunneling Diodes For Telecom Wavelength Single Photon Detection, H. W. Li, Paul J. Simmonds, H. E. Beere, B. E. Kardynał, D. A. Ritchie, A. J. Shields Sep 2007

Quantum Dot Resonant Tunneling Diodes For Telecom Wavelength Single Photon Detection, H. W. Li, Paul J. Simmonds, H. E. Beere, B. E. Kardynał, D. A. Ritchie, A. J. Shields

Paul J. Simmonds

Single photon detection was realized at a telecom wavelength with quantum dot resonant tunneling diodes grown on an InP substrate. The structure contains a AlAs/In0.53Ga0.47As/AlAs quantum well with InAs quantum dots grown on the top AlAs barrier. The single photon detection efficiency of the device under 1310 nm illumination was measured to be about 0.35% ± 0.07% with a dark count rate of 1.58×10-6 ns-1. This corresponds to an internal efficiency of 6.3%.


Quantum Dot Resonant Tunneling Diode For Telecommunication Wavelength Single Photon Detection, H. W. Li, B. E. Kardynał, P. See, A. J. Shields, P. Simmonds, H. E. Beere, D. A. Ritchie Aug 2007

Quantum Dot Resonant Tunneling Diode For Telecommunication Wavelength Single Photon Detection, H. W. Li, B. E. Kardynał, P. See, A. J. Shields, P. Simmonds, H. E. Beere, D. A. Ritchie

Paul J. Simmonds

The authors present a quantum dot (QD) based single photon detector operating at a fiber optic telecommunication wavelength. The detector is based on an AlAs/In0.53Ga0.47As/AlAs double-barrier resonant tunneling diode containing a layer of self-assembled InAs QDs grown on an InP substrate. The device shows an internal efficiency of about 6.3% with a dark count rate of 1.58 × 10−6 ns−1 for 1310 nm photons.


Growth By Molecular Beam Epitaxy Of Self-Assembled Inas Quantum Dots On Inalas And Ingaas Lattice-Matched To Inp, Paul J. Simmonds, H W. Li, H E. Beere, P See, A J. Shields, D A. Ritchie May 2007

Growth By Molecular Beam Epitaxy Of Self-Assembled Inas Quantum Dots On Inalas And Ingaas Lattice-Matched To Inp, Paul J. Simmonds, H W. Li, H E. Beere, P See, A J. Shields, D A. Ritchie

Paul J. Simmonds

The authors report the results of a detailed study of the effect of growth conditions, for molecular beam epitaxy, on the structural and optical properties of self-assembled InAs quantum dots (QDs) on In0.524Al0.476As. InAs QDs both buried in, and on top of, In0.524Al0.476As were analyzed using photoluminescence (PL) and atomic force microscopy. InAs QD morphology and peak PL emission wavelength both scale linearly with deposition thickness in monolayers (MLs). InAs deposition thickness can be used to tune QD PL wavelength by 170 nm/ML, over a range of almost 700 nm. Increasing growth …