Compact Reconfigurable Binary-Decision-Diagram Logic Circuit on a GaAs Nanowire Network

We describe a reconfigurable binary-decision-diagram logic circuit based on Shannon's expansion of Boolean logic function and its graphical representation on a semiconductor nanowire network. The circuit is reconfigured by using programmable switches that electrically connect and disconnect a small number of branches. This circuit has a compact structure with a small number of devices compared with the conventional look-up table architecture. A variable Boolean logic circuit was fabricated on an etched GaAs nanowire network having hexagonal topology with Schottky wrap gates and SiN-based programmable switches, and its correct logic operation together with dynamic reconfiguration was demonstrated.

高功率GaN基激光器列阵的工艺制作和特性研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-13T08:09:45Z No. of bitstreams: 1 季 莲--高功率GaN基激光器列阵的工艺制作和特性研究.pdf: 2893344 bytes, checksum: 91687f7e5453fbcf7e91203e116a216e (MD5)

(In,Cr)As 量子点的结构与磁性

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-21T05:26:37Z No. of bitstreams: 1 孟海娟--(In,Cr)As 量子点的结构与磁性.pdf: 3989937 bytes, checksum: e18f17f209e486458dc27d0ef94e173c (MD5)

Rashba electron transport in one-dimensional quantum waveguides

The properties of Rashba wave function in the planar one-dimensional waveguide are studied, and the following results are obtained. Due to the Rashba effect, the plane waves of electron with the energy E divide into two kinds of waves with the wave vectors k(1)=k(0)+k(delta) and k(2)=k(0)-k(delta), where k(delta) is proportional to the Rashba coefficient, and their spin orientations are +pi/2 (spin up) and -pi/2 (spin down) with respect to the circuit, respectively. If there is gate or ferromagnetic contact in the circuit, the Rashba wave function becomes standing wave form exp(+/- ik(delta)l)sin[k(0)(l-L)], where L is the position coordinate of the gate or contact. Unlike the electron without considering the spin, the phase of the Rashba plane or standing wave function depends on the direction angle theta of the circuit. The travel velocity of the Rashba waves with the wave vector k(1) or k(2) are the same hk(0)/m*. The boundary conditions of the Rashba wave functions at the intersection of circuits are given from the continuity of wave functions and the conservation of current density. Using the boundary conditions of Rashba wave functions we study the transmission and reflection probabilities of Rashba electron moving in several structures, and find the interference effects of the two Rashba waves with different wave vectors caused by ferromagnetic contact or the gate. Lastly we derive the general theory of multiple branches structure. The theory can be used to design various spin polarized devices.

基于横向外延生长的GaN LED 特性研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-13T08:18:55Z No. of bitstreams: 1 毕业论文_王良吉.pdf: 5299270 bytes, checksum: 6b0aeaa63a52321331f321143a5b0a09 (MD5)

Fe/GaAs结构体系中自旋注入与探测的研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-21T05:28:49Z No. of bitstreams: 1 吴昊_Fe-GaAs结构体系中自旋注入与探测的研究.pdf: 6719940 bytes, checksum: e75d378a532a0ba454bd429b8b7b66b7 (MD5)

Temperature dependence of hole spin relaxation in ultrathin InAs monolayers

The temperature dependence of hole spin relaxation time in both neutral and n-doped ultrathin InAs monolayers has been investigated. It has been suggested that D'yakonov-Perel (DP) mechanism dominates the spin relaxation process at both low and high temperature regimes. The appearance of a peak in temperature dependent spin relaxation time reveals the important contribution of Coulomb scatterings between carriers to the spin kinetics at low temperature, though electron-phonon scattering becomes dominant at higher temperatures. Increased electron screening effect in the n-doped sample has been suggested to account for the shortened spin relaxation time compared with the undoped one. The results suggest that hole spins are also promising for building solid-state qubits.

二维光子晶体平板光开关与传感特性研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-21T05:32:59Z No. of bitstreams: 1 陈率--二维光子晶体平板光开关与传感特性研究.pdf: 3086910 bytes, checksum: 3d5e741ebf5125471bc1baa11c312cac (MD5)

稀磁半导体(Ga,Mn)As 中自旋动力学的探索与研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-07-02T05:55:53Z No. of bitstreams: 1 罗晶：稀磁半导体 (Ga,Mn)As中自旋动力学的探索与研究.pdf: 2131823 bytes, checksum: 74e83e69fc6f6b1c7247db0e1c2a8e51 (MD5)

Mechanical and chemical bonding properties of ground state BeH2

The crystal structure, mechanical properties and electronic structure of ground state BeH2 are calculated employing the first-principles methods based on the density functional theory. Our calculated structural parameters at equilibrium volume are well consistent with experimental results. Elastic constants, which well obey the mechanical stability criteria, are firstly theoretically acquired. The bulk modulus B, Shear modulus G, Young's modulus E, and Poisson's ratio upsilon are deduced from the elastic constants. The bonding nature in BeH2 is fully interpreted by combining characteristics in band structure, density of states, and charge distribution. The ionicity in the Be-H bond is mainly featured by charge transfer from Be 2s to H 1s atomic orbitals while its covalency is dominated by the hybridization of H 1s and Be 2p states. The Bader analysis of BeH2 and MgH2 are performed to describe the ionic/covalent character quantitatively and we find that about 1.61 (1.6) electrons transfer from each Be (Mg) atom to H atoms.

40 Gb/s 光电探测器小信号测试法和大信号测试系统研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-21T07:30:12Z No. of bitstreams: 1 张邦宏--40 Gbs 光电探测器小信号测试法和大信号测试系统研究.pdf: 3057511 bytes, checksum: 0c2a4acd2c1687f6c3ee554b01030fed (MD5)

Electrically controllable RKKY interaction in semiconductor quantum wires

We demonstrate in theory that it is possible to all-electrically manipulate the RKKY interaction in a quasi-one-dimensional electron gas embedded in a semiconductor heterostructure, in the presence of Rashba and Dresselhaus spin-orbit interaction. In an undoped semiconductor quantum wire where intermediate excitations are gapped, the interaction becomes the short-ranged Bloembergen-Rowland superexchange interaction. Owing to the interplay of different types of spin-orbit interaction, the interaction can be controlled to realize various spin models, e.g., isotropic and anisotropic Heisenberg-like models, Ising-like models with additional Dzyaloshinsky-Moriya terms, by tuning the external electric field and designing the crystallographic directions. Such controllable interaction forms a basis for quantum computing with localized spins and quantum matters in spin lattices.

光外差法产生微波信号的基础研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-21T07:31:55Z No. of bitstreams: 1 张红广--博士学位论文.pdf: 2315275 bytes, checksum: 318b15e019abb6984f9f8bf9dc912e56 (MD5)

宽带隙半导体纳米材料的制备及物理化学性质的研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-07-21T01:25:08Z No. of bitstreams: 1 出站报告 孟秀清.pdf: 2264422 bytes, checksum: 95e11be05edd4dd8691cdaf8fdbeb368 (MD5)

Quantum tunneling through graphene nanorings

We investigate theoretically quantum transport through graphene nanorings in the presence of a perpendicular magnetic field. Our theoretical results demonstrate that the graphene nanorings behave like a resonant tunneling device, contrary to the Aharonov-Bohm oscillations found in conventional semiconductor rings. The resonant tunneling can be tuned by the Fermi energy, the size of the central part of the graphene nanorings and the external magnetic field.