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Tensile-Strained Growth On Low-Index Gaas, Paul J. Simmonds, Minjoo Larry Lee
Tensile-Strained Growth On Low-Index Gaas, Paul J. Simmonds, Minjoo Larry Lee
Paul J. Simmonds
We present a comparative study of the growth of tensile-strained GaP on the four low-index surfaces of GaAs: (001), (110), (111)A, and (111)B. For each surface orientation we outline the growth conditions required for smooth GaAshomoepitaxy. We are able to predict the resulting surface morphology when GaP is deposited onto these four GaAssurfaces by considering the influence of surface orientation on tensile strain relief. GaP deposited on GaAs(001) forms extremely smooth, planar layers. In contrast, the elastic relief of tensile strain on both GaAs(110) and GaAs(111)A leads to the three-dimensional self-assembly of GaP into dislocation-free nanostructures. Similarities between tensile and …
Structural And Optical Properties Of Inas/Alassb Quantum Dots With Gaas(Sb) Cladding Layers, Paul J. Simmonds, Ramesh Babu Laghumavarapu, Meng Sun, Andrew Lin, Charles J. Reyner, Baolai Liang, Diana L. Huffaker
Structural And Optical Properties Of Inas/Alassb Quantum Dots With Gaas(Sb) Cladding Layers, Paul J. Simmonds, Ramesh Babu Laghumavarapu, Meng Sun, Andrew Lin, Charles J. Reyner, Baolai Liang, Diana L. Huffaker
Paul J. Simmonds
We investigate the effect of GaAs1−xSbxcladding layer composition on the growth and properties of InAsself-assembledquantum dots surrounded by AlAs0.56Sb0.44 barriers. Lowering Sb-content in the GaAs1−xSbx improves the morphology of the InAs quantum dots and reduces cladding layer alloy fluctuations. The result is a dramatic increase in photoluminescence intensity from the InAs quantum dots, with a peak at 0.87 eV. The emission energy exhibits a cube root dependence on excitation power, consistent with the type-II band alignment of the quantum dots. The characteristics of this quantum dot system show promise for …
Self-Assembly On (111)-Oriented Iii-V Surfaces, Paul J. Simmonds, Minjoo Larry Lee
Self-Assembly On (111)-Oriented Iii-V Surfaces, Paul J. Simmonds, Minjoo Larry Lee
Paul J. Simmonds
We demonstrate the self-assembly of tensile strained GaP into three-dimensional dots on GaAs(111)A. Size and areal density of the dislocation-free GaPdots are readily tunable with both substrate temperature and deposition thickness. GaP dot growth obeys island scaling theory, allowing us to predict dot size distributions a priori.
Tensile Strained Island Growth At Step-Edges On Gaas(110), Paul J. Simmonds, M. L. Lee
Tensile Strained Island Growth At Step-Edges On Gaas(110), Paul J. Simmonds, M. L. Lee
Paul J. Simmonds
We report the growth of tensile strained GaP islands on a GaAs(110) surface. Three-dimensional island formation proceeds via a step-edge nucleation process. To explain the dislocation-free nature of these islands, we consider the kinetics of strain relief within the context of a model for dislocation glide as a function of surface orientation and sign of strain.
A Comparison Of New Methods For Generating Energy-Minimizing Configurations Of Patchy Particles, Eric Jankowski, Sharon C. Glotzer
A Comparison Of New Methods For Generating Energy-Minimizing Configurations Of Patchy Particles, Eric Jankowski, Sharon C. Glotzer
Eric Jankowski
Increasingly complex particles are pushing the limits of traditional simulation techniques used to study self-assembly. In this work, we test the use of a learning-augmented Monte Carlo method for predicting low energy configurations of patchy particles shaped like “Tetris®” pieces. We extend this method to compare it against Monte Carlo simulations with cluster moves and introduce a new algorithm—bottom-up building block assembly—for quickly generating ordered configurations of particles with a hierarchy of interaction energies.
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
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 …