The Nonlinear Absorption Coefficient of Strong Electromagnetic Waves Caused by Electrons Confined in Quantum Wires

Nguyen Quang Bau,Hoang Dinh Trien 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.1

Analytic expressions for the nonlinear absorption coefficient of a strong electromagnetic wave caused by electrons confined in cylindrical quantum wires are calculated by using the quantum kinetic equation for electrons. The problem is considered for electron-phonon scattering mechanisms (electron-optical phonon scattering and electron-acoustic phonon scattering) in the absence of an external magnetic field and for electron-optical phonon scattering in the presence of an external magnetic field. The dependence of the nonlinear absorption coefficient on the intensity E0 and the frequency of the external strong electromagnetic wave, the temperature T of the system, the radius of the wires R, and the cyclotron frequency wc (for the case of the presence of an external magnetic field) is obtained. The analytic expressions are numerically calculated and discussed for GaAs/GaAsAl quantum wires. The results are compared with those for normal bulk semiconductors and quantum wells to show the differences.

GaAs/ AlGaAs Crescent-shaped Quantum Wires

김남영 광운대학교 신기술연구소 1997 신기술연구소논문집 Vol.26 No.-

A central goal in GaAs /AlGaAs crescent-shaped quantum wires (QWRs) modeling is to find the lowest-energy eigenstates of this structure. The novel numerical technique such as adaptive potential alternating direction implicit (APADI) scheme has been developed to model the quantum-confined crescent-shaped structure. In this new method, the useful decomposition of the potential energy, which accelerates the ground state of Schro¨nger operator in multiple space dimensions would be used to improve the ultimate accuracy. The simulation results are given to show the electronic spectroscopy in GaAs / AlGaAs crescentshaped QWRs.

Design of Wire-Crossing Technique Based on Difference of Cell State in Quantum-Dot Cellular Automata

Sang-Ho Shin,Jun-Cheol Jeon,Kee-Young Yoo 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.4

Engineering and Manipulating Topological Qubits in 1D Quantum Wires

Panagiotis Kotetes,Gerd Sch¨on,Alexander Shnirman 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.10

We investigate the Josephson effect in TNT and NTN junctions, consisting of topological (T)and normal (N) phases of semiconductor-superconductor 1D heterostructures in the presence of a Zeeman field. A key feature of our setup is that, in addition to the variation of the phase of the superconducting order parameter, we allow the orientation of the magnetic field to change along the junction. We find a novel magnetic contribution to the Majorana Josephson coupling that permits the Josephson current to be tuned by changing the orientation of the magnetic field along the junction. We also predict that a spin current can be generated by a finite superconducting phase difference, rendering these materials potential candidates for spintronic applications. Finally,this new type of coupling not only constitutes a unique fingerprint for the existence of Majorana bound states but also provides an alternative pathway for manipulating and braiding topological qubits in networks of wires.

Polarizability of a hydrogenic donor impurity in a ridge quantum wire

R. Khordad,A. Gharaati,M. Haghparast 한국물리학회 2010 Current Applied Physics Vol.10 No.1

We use in this paper the variational method to calculate the polarizability of a hydrogenic donor impurity,in the presence of electric field, in a V-groove GaAs/AlxGa1-xAs quantum wire. The carrier ground states are analytically obtained by an effective potential scheme together with a suitable coordinate transformation that allows the decoupling of the two-dimensional Schrodinger equation. According to the results obtained from the present work for polarizability and binding energy reveals that the impurity position and field direction play important roles.

양자선초격자에서 전기포논공명

김석환,이상칠 한국물리학회 2013 새물리 Vol.63 No.2

The electric conductivity in quantum-wire superlattices with a parabolic confinement potential is investigated as functions of the temperature, the electronic density, the miniband width, and the period of the superlattices, repectively, by using the quantum transport theory. The dependences of the plateau region between neighboring electrophonon resonance (EPR) peaks and of the EPR condition from the relaxation function due to the scattering between an electron and an optical phonon on the confinement frequency of the parabolic confinement potential and on the miniband widths are also studied analytically. Furthermore, the behaviors of the EPR lineshape, such as the antiresonance of the EPR peaks for various confinement frequencies of the parabolic confinement potential and the miniband widths are discussed. 포물선형 구속퍼텐셜을 가지는 양자선초격자에 양자수송 이론을 적용하여전기전도도를 온도, 전자밀도, 미니밴드 너비, 초격자 주기의 함수로구하였다. 또한 전자와 광학포논 사이의 산란에 기인한 이완함수를구하여 전기포논공명 조건과 공명정점 사이의 평활영역 조건을 포물선형구속퍼텐셜의 구속진동수와 미니밴드 너비의 함수로 얻었다. 나아가포물선형 구속퍼텐셜의 다양한 구속진동수와 미니밴드 너비의 함수로반공명과 같은 전기포논공명 선모양에 대한 거동을 논의하였다.

Influence of Phonon Confinement on the Optically-detected Electrophonon Resonance Linewidth in Rectangular Quantum Wires

Tran Cong Phong,Le Thi Thu Phuong,Huynh Vinh Phuc,Pham Tuan Vinh 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.2

We investigate the influence of phonon confinement on the optically-detected electrophonon resonance (ODEPR) effect and ODEPR linewidth in rectangular quantum wires (RQW). The ODEPR conditions as functions of the wire’s size and the photon energy are also obtained. The splittings of ODEPR peaks caused by the confined phonon are discussed. The numerical result for a specific RQW shows that in the two cases of confined and bulk phonons, the linewidth decreases with increasing wire size and increases with increasing temperature. Furthermore, in the small range of the wire’s size (<i>L</i> ≤ 40 nm), phonon confinement plays an important role and cannot be neglected in reaching the ODEPR linewidth.

Cyclotron Resonance Linewidth in GaAs/AlAs Quantum Wires

Huynh Vinh Phuc,Le Dinh Quang,Tran Cong Phong 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.9

In this paper, we study cyclotron-resonance linewidths in an electron-phonon system with the presence of a z-directional triangular potential and a y-directional parabolic potential. A general analytical expression for the absorption power is obtained in the presence of an external static magnetic field applied to the sample along the z-axis. The dependence of the absorption power on the photon energy is numerically calculated and graphically plotted for a specific GaAs/AlAs quantum wire. From graphs of the absorption power, we identified the locations of the cyclotron resonance peaks and obtained the cyclotron resonance linewidth (CRLW) as profiles of the curves. The temperature and the magnetic field dependences of the CRLW have been investigated. The CRLW is shown to increase with increasing temperature and magnetic field. In this paper, we study cyclotron-resonance linewidths in an electron-phonon system with the presence of a z-directional triangular potential and a y-directional parabolic potential. A general analytical expression for the absorption power is obtained in the presence of an external static magnetic field applied to the sample along the z-axis. The dependence of the absorption power on the photon energy is numerically calculated and graphically plotted for a specific GaAs/AlAs quantum wire. From graphs of the absorption power, we identified the locations of the cyclotron resonance peaks and obtained the cyclotron resonance linewidth (CRLW) as profiles of the curves. The temperature and the magnetic field dependences of the CRLW have been investigated. The CRLW is shown to increase with increasing temperature and magnetic field.

Magnetization Anisotropy of Semiconductor Quantum Wires with Magnetoelectric Quantization

김남미,Heesang Kim 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.2

The carrier magnetization of diluted magnetic semiconductor quantum wires having hybrid magnetoelectric quantization has been investigated. The magnetization as a function of the chemical potential shows that magnetic ions in semiconductor quantum wires enhance the magnetization and induce nonzero magnetization in a low-chemical-potential region. Magnetization anisotropy is not predominant in quantum wires while it is manifested in quantum wells because this anisotropy originates from changes in the density of states. The magnetization of quantum wires shows superimposed oscillations due to two hybrid eigenfrequencies. The carrier magnetization of diluted magnetic semiconductor quantum wires having hybrid magnetoelectric quantization has been investigated. The magnetization as a function of the chemical potential shows that magnetic ions in semiconductor quantum wires enhance the magnetization and induce nonzero magnetization in a low-chemical-potential region. Magnetization anisotropy is not predominant in quantum wires while it is manifested in quantum wells because this anisotropy originates from changes in the density of states. The magnetization of quantum wires shows superimposed oscillations due to two hybrid eigenfrequencies.

여러 가지 높이를 갖는 삼각형 구조 InGaAs/GaAs 양자세선 구조 성장

김성일,김영환,한일기,Kim Seong-Il,Kim Young-Whan,Han Il-Ki 한국재료학회 2004 한국재료학회지 Vol.14 No.6

InGaAs/GaAs quantum wire structures were grown by low pressure metalorganic chemical vapor deposition by using selective area epitaxy.$ In_{ 0.2}$$Ga_{0.8}$ As/GaAs quantum wire structures were grown on a $SiO_2$ masked GaAs substrate. Quantum wire structures with sharp tips and smooth side walls were grown. We have grown InGaAs/GaAs quantum wire structures using variously opened width of the $SiO _2$ mask. Even though the opening widths of $SiO_2$ masked GaAs substrate were different, similar shapes of triangular structures were grown. Using various kinds of differently opened $SiO_2$ masked area, it would be possible to grow quantum wire structures with various thicknesses. The quantum wire structures are formed near the pinnacle of the triangular structure. Therefore, the fabrication of the uniquely designed integrated optical devices which include light emitting sources of multiple wavelength is possible.