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Author: Dipta Saha Publisher: ISBN: Category : Languages : en Pages : 123
Book Description
The calculations of CR spectra, valence Landau suband structure, and average z component of the spins explain the differences between the CR measurements that are observed in molecular beam epitaxy (MBE) and metal organic vapor phase epitaxy (MOVPE) samples, and the higher Curie temperature in the MOVPE structures. In the OPNMR experiments on AlGaAs/GaAs MQW, the sign change of the calculated electron spin polarization agrees with the sign change of the OPNMR signal. This sign change has not been observed in bulk GaAs. The strain effect and density of states in the strained MQW are responsible for this sign change. The calculated magneto-absorption with biaxial strain effects included more accurately reproduces the experimental results of AlInSb/InSb parabolic MQW. Comparing the results with that of the AlInSb/InSb square MQW indicates that the shape of the confinement affects the magneto-absorption significantly.
Author: Dipta Saha Publisher: ISBN: Category : Languages : en Pages : 123
Book Description
The calculations of CR spectra, valence Landau suband structure, and average z component of the spins explain the differences between the CR measurements that are observed in molecular beam epitaxy (MBE) and metal organic vapor phase epitaxy (MOVPE) samples, and the higher Curie temperature in the MOVPE structures. In the OPNMR experiments on AlGaAs/GaAs MQW, the sign change of the calculated electron spin polarization agrees with the sign change of the OPNMR signal. This sign change has not been observed in bulk GaAs. The strain effect and density of states in the strained MQW are responsible for this sign change. The calculated magneto-absorption with biaxial strain effects included more accurately reproduces the experimental results of AlInSb/InSb parabolic MQW. Comparing the results with that of the AlInSb/InSb square MQW indicates that the shape of the confinement affects the magneto-absorption significantly.
Author: Xingyuan Pan Publisher: ISBN: Category : Languages : en Pages :
Book Description
ABSTRACT: Next generation of semiconductor device will not only based on the charge transport properties of the carrier, but also their spin degree of freedom. In order to understand or predict how those devices work one need to understand the spin-dependent electronic structures of both bulk and low-dimensional semiconductors. We have theoretically studied the spin-dependent Landau levels for electrons or holes in bulk GaAs system and AlInSb/InSb multiple quantum wells system. We use the envelope function approximation for the electronic and magneto-optical properties of AlInSb/InSb superlattices. Our model includes the conduction electrons, heavy holes, light holes and the split-off holes for a total of 8 bands when spin is taken into account. It is a generalization of the Pidgeon-Brown model to include the wave vector dependence of the electronic states, as well as quantization of wave vector due to multiple quantum well superlattice effects. In addition, we take strain effects into account by assuming pseudomorphic growth conditions. For bulk GaAs system, we calculated the spin-dependent absorption coefficients which can be directly compared with the optically pumped NMR experiment. We show that the optically pumped NMR is a complimentary tool to traditional magneto optical absorption measurement, in the sense that optically pumped NMR is more sensitive to the light hole transitions which are very hard to resolve in the traditional magneto absorption measurement. For the AlInSb/InSb multiple quantum well system, we calculated both the magneto absorption spectra and 10 the cyclotron resonance spectra. We compare both spectra to experimental results and achieve a good agreement. This agreement assures us that our understanding of the valence band structure of the narrow gap InSb materials are correct.
Author: Marcin L. Sadowski Publisher: Springer Science & Business Media ISBN: 9401141584 Category : Science Languages : en Pages : 443
Book Description
Optical methods for investigating semiconductors and the theoretical description of optical processes have always been an important part of semiconductor physics. Only the emphasis placed on different materials changes with time. Here, a large number of papers are devoted to quantum dots, presenting the theory, spectroscopic investigation and methods of producing such structures. Another major part of the book reflects the growing interest in diluted semiconductors and II-IV nanosystems in general. There are also discussions of the fascinating field of photonic crystals. `Classical' low dimensional systems, such as GsAs/GaAlAs quantum wells and heterostructures, still make up a significant part of the results presented, and they also serve as model systems for new phenomena. New materials are being sought, and new experimental techniques are coming on stream, in particular the combination of different spectroscopic modalities.
Author: Junichiro Kono Publisher: CRC Press ISBN: 148226921X Category : Science Languages : en Pages : 636
Book Description
This volume forms a solid presentation in several important areas of NGS research, including materials, growth and characterization, fundamental physical phenomena, and devices and applications. It examines the novel material of InAs and its related alloys, heterostructures, and nanostructures as well as more traditional NGS materials such as InSb, PbTe, and HgCdTe. Several chapters cover carbon nanotubes and spintronics, along with spin-orbit coupling, nonparabolicity, and large g-factors. The book also deals with the physics and applications of low-energy phenomena at the infrared and terahertz ranges.
Author: Publisher: ISBN: Category : Languages : en Pages : 12
Book Description
First-principles calculations were performed of a variety of materials systems of potential interest in spintronics. A comprehensive study was made of transitional metal doping in SiC and their magnetic properties. The trends in magnetic properties and in the preference for rocksalt versus zincblende structure were studied for the entire series of transition metal nitrides. The LSDA+U method was implemented in the FP-LMTO approach and applied to rare-earth nitrides and related compounds. A study was made of half-metallicity in zincblende transition metal compounds. A study was made of Mn doping of ScN. It was found to be a potentially interesting dilute magnetic semiconductor system. Exchange interactions in this system were calculated using a linear response approach and cluster variation method calculations indicate a Tc above room temperature should be feasible in this material. Calculations of the optical spectra of antifeorromagnetic MnN were compared with experimental data.
Author: Shuoyuan Chen Publisher: ISBN: Category : Languages : en Pages :
Book Description
Localized surface plasmon resonance (LSPR) in semiconductor nanostructures have attracted intense attention recently for its broad application in bio-imaging, chemical sensing, photocatalysis, and photovoltaics. Compared to the LSPR in metallic nanocrystals (NCs), LSPR in semiconductor NCs is highly tunable in the infrared region by tailoring chemical composition and stoichiometry. Moreover, LSPR along with external magnetic field allows the exploration of magneto-plasmonic coupling in single-phase semiconductors, opening up the magneto-optical ways to control charge carriers. In this thesis, we focus on the LSPR as well as magneto-optical properties of indium nitride (InN), providing valuable insights into the insufficiently researched III-V group semiconductors. Wurtzite phase InN NCs were successfully synthesized using the low-temperature colloidal method, and the plasmon intensity is tunable by changing the synthesis environment and varying doping concentrations of aluminum and titanium ions. Due to the combined effects of conduction band non-parabolicity and intraband transition, our InN NCs with different plasmon intensities have an almost fixed plasmonic energy of 0.37 eV. Besides, the optical bandgap of pure InN NCs ranges from 1.5 to 1.75 eV, depending on the reaction conditions, while that of the Al and Ti-doped InN varies from 1.65 to 1.85 eV. The plasmon-dependent phonon change is evaluated by the Raman spectroscopy. Differences in the longitudinal-optical (LO) phonon mode was observed for InN with high and low plasmon intensity. The magneto-optical properties of InN NCs were measured by the magnetic circular dichroism (MCD). The field-dependence and temperature-independence of the measured MCD spectra were investigated, and the plasmon-induced polarization of carriers was demonstrated. Tuning of the carrier polarization by varying LSPR and external magnetic field corroborates the hypothesis of non-resonant coupling between plasmons and excitons in a single-phase semiconductor. The results of this work demonstrate that LSPR can act as a degree of freedom in manipulating electrons in technologically-important III-V nanostructures and lead to potential applications in photonics and quantum computing at room temperature. Finally, InN nanowires (NWs) with LSPR were fabricated via low-temperature chemical vapor deposition (CVD) approach, laying the groundwork for the future research of LSPR and magneto-plasmonics in a one-dimensional system.
Author: Dipta Saha
Author: Dipta Saha
Author: Xingyuan Pan
Author: Marcin L. Sadowski
Author: Feng Liu
Author: Junichiro Kono
Author: 
Author: Sung-Ryul Yang
Author: 
Author: Shuoyuan Chen
Author: Michal Grochol