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Coulomb correlations evidenced in the magneto-optical spectra of charged excitons in semiconductor quantum dots  [PDF]
D. Y. Oberli,M. Byszewski,B. Chalupar,E. Pelucchi,A. Rudra,E. Kapon
Physics , 2008,
Abstract: The emission spectral pattern of a charged exciton in a semiconductor quantum dot is composed of a quadruplet of linearly polarized lines in the presence of a magnetic field oriented perpendicularly to the direction of the photon momentum. By measuring the Zeeman splittings, we obtain the effective g factors of the carriers and find that the hole g factor is very sensitive to the QD shape asymmetry. By comparing the effective g factors obtained for the neutral and the charged excitons in the same quantum dot, we uncover the role of Coulomb correlations in these excitonic states.
Optical Biosensors Based on Semiconductor Nanostructures  [PDF]
Raúl J. Martín-Palma,Miguel Manso,Vicente Torres-Costa
Sensors , 2009, DOI: 10.3390/s90705149
Abstract: The increasing availability of semiconductor-based nanostructures with novel and unique properties has sparked widespread interest in their use in the field of biosensing. The precise control over the size, shape and composition of these nanostructures leads to the accurate control of their physico-chemical properties and overall behavior. Furthermore, modifications can be made to the nanostructures to better suit their integration with biological systems, leading to such interesting properties as enhanced aqueous solubility, biocompatibility or bio-recognition. In the present work, the most significant applications of semiconductor nanostructures in the field of optical biosensing will be reviewed. In particular, the use of quantum dots as fluorescent bioprobes, which is the most widely used application, will be discussed. In addition, the use of some other nanometric structures in the field of biosensing, including porous semiconductors and photonic crystals, will be presented.
Interplay between Phonon Confinement and Fano Effect on Raman line shape for semiconductor nanostructures: Analytical study  [PDF]
Priyanka Yogi,Shailendra K. Saxena,Suryakant Mishra,Vikash Mishra,Hari M. Rai,Ravikiran Late,Vivek Kumar,Bipin Joshi,Pankaj R. Sagdeo,Rajesh Kumar
Physics , 2015,
Abstract: Theoretical Raman line shape functions have been studied to take care of quantum confinement effect and Fano effect individually and jointly. The characteristics of various Raman line shapes have been studied in terms of the broadening and asymmetry of Raman line shapes. It is shown that the asymmetry in the Raman line-shape function caused by these two effects individually does not add linearly to give asymmetry of line-shape generated by considering the combined effect. This indicates existence of interplay between the two effects. The origin of interplay lies in the fact that Fano effect itself depends on quantum confinement effect and in turn provides an asymmetry. This can not be explained by considering the two effects contribution independent of each other.
Resonant transport throught semiconductor nanostructures  [PDF]
E. R. Racec,P. N. Racec,U. Wulf
Physics , 2004,
Abstract: Transport through semiconductor nanostructures is a quantum-coherent process. This paper focuses on systems in which the electron's dynamics is ballistic and the transport is dominated by the scattering from structure boundaries. Opposite to the well-known case of the nuclear reactions, the potentials defining semiconductor structures are nonspherically symmetric and the asymptotic motion of the electrons is determined by the different potential levels in the contacts. For this special type of potential the mathematical foundations for the scattering theoretical description of the transport phenomena are presented. The transport properties of the system are then derived from the scattering matrix using the Landauer-Buttiker formalism. A rigorous analysis of the analytical properties of the S matrix leads to the most general resonant line shape described by a Fano function with a complex asymmetry parameter. On this basis the resonant and nonresonant contributions to the conductance and capacitance of the system are identified.
Spin dynamics in semiconductor nanostructures  [PDF]
M. W. Wu,M. Q. Weng,J. L. Cheng
Physics , 2006,
Abstract: We review our theoretical investigation on the spin relaxation/dephasing in spin precession and spin diffusion/transport in semiconductor nanostructures based on the kinetic spin Bloch equation approach.
Finger-gate manipulated quantum transport in a semiconductor narrow constriction with spin-orbit interactions and Zeeman effect  [PDF]
Chi-Shung Tang,Shu-Yu Chang,Shun-Jen Cheng
Physics , 2012, DOI: 10.1103/PhysRevB.86.125321
Abstract: The authors investigate quantum transport in a narrow constriction fabricated by narrow band gap semiconductor materials with spin-orbit (SO) couplings. We consider the Rashba-Dresselhaus (RD) spin-orbit interactions (SOIs) and the Zeeman effect induced by an in-plane magnetic field along the transport direction. The interplay of the RD-SOI and the Zeeman effect may induce a SOI-Zeeman gap and influence the transport properties. We demonstrate that an attractive scattering potential may induce electron-like quasi-bound-state feature and manifest the RD-SOI-Zeeman induced Fano line-shape in conductance. Furthermore, a repulsive scattering potential may induce hole-like quasi-bound-state feature on the subband top of the lower spin branch.
Overhauser frequency shifts in semiconductor nanostructures  [PDF]
I. Tifrea,M. Poggio,D. D. Awschalom,M. E. Flatté
Physics , 2008,
Abstract: We calculate the Overhauser frequency shifts in semiconductor nanostructures resulting from the hyperfine interaction between nonequilibrium electronic spins and nuclear spins. The frequency shifts depend on the electronic local density of states and spin polarization as well as the electronic and nuclear spin relaxation mechanisms. Unlike previous calculations, our method accounts for the electron confinement in low dimensional semiconductor nanostructures, resulting in both nuclear spin polarizations and Overhauser shifts that are strongly dependent on position. Our results explain previously puzzling measurements of Overhauser shifts in an Al$_x$Ga$_{1-x}$As parabolic quantum well by showing the connection between the electron spin lifetime and the frequency shifts.
Pseudospin Quantum Computation in Semiconductor Nanostructures  [PDF]
V. W. Scarola,K. Park,S. Das Sarma
Physics , 2003, DOI: 10.1103/PhysRevLett.91.167903
Abstract: We theoretically show that spontaneously interlayer-coherent bilayer quantum Hall droplets should allow robust and fault-tolerant pseudospin quantum computation in semiconductor nanostructures with voltage-tuned external gates providing qubit control and a quantum Ising Hamiltonian providing qubit entanglement. Using a spin-boson model we estimate decoherence to be small $(\sim 10^{-5})$.
Quantum Transport in Semiconductor Nanostructures  [PDF]
C. W. J. Beenakker,H. van Houten
Physics , 2004, DOI: 10.1016/S0081-1947(08)60091-0
Abstract: I. Introduction (Preface, Nanostructures in Si Inversion Layers, Nanostructures in GaAs-AlGaAs Heterostructures, Basic Properties). II. Diffusive and Quasi-Ballistic Transport (Classical Size Effects, Weak Localization, Conductance Fluctuations, Aharonov-Bohm Effect, Electron-Electron Interactions, Quantum Size Effects, Periodic Potential). III. Ballistic Transport (Conduction as a Transmission Problem, Quantum Point Contacts, Coherent Electron Focusing, Collimation, Junction Scattering, Tunneling). IV. Adiabatic Transport (Edge Channels and the Quantum Hall Effect, Selective Population and Detection of Edge Channels, Fractional Quantum Hall Effect, Aharonov-Bohm Effect in Strong Magnetic Fields, Magnetically Induced Band Structure).
Enhancement of Carrier Mobility in Semiconductor Nanostructures by Dielectric Engineering  [PDF]
Debdeep Jena,Aniruddha Konar
Physics , 2007, DOI: 10.1103/PhysRevLett.98.136805
Abstract: We propose a technique for achieving large improvements in carrier mobilities in 2- and 1-dimensional semiconductor nanostructures by modifying their dielectric environments. We show that by coating the nanostructures with high-$\kappa$ dielectrics, scattering from Coulombic impurities can be strongly damped. Though screening is also weakened, the damping of Coulombic scattering is much larger, and the resulting improvement in mobilities of carriers can be as much as an order of magnitude for thin 2D semiconductor membranes, and more for semiconductor nanowires.
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