光子晶体中量子点的自发辐射及自旋-轨道耦合作用下的光跃迁

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-02T02:16:02Z No. of bitstreams: 1 朱正勇博士学位论文.pdf: 1551245 bytes, checksum: 90077759cea6086e52b0fa567b969d0c (MD5)

Growing 20 cm Long DWNTs/TWNTs at a Rapid Growth Rate of 80-90 mu m/s

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-04-13T16:03:37Z No. of bitstreams: 1 Growing 20 cm Long DWNTsTWNTs at a Rapid Growth Rate of 80-90 mu ms .pdf: 3229914 bytes, checksum: 0259795afb443dc6901c11df5ecd325a (MD5)

GaAs 基1.55 微米异变InGaAs高性能探测器的研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-07T06:25:37Z No. of bitstreams: 1 朱彬：异变1.55微米InGaAs高性能探测器的研究.pdf: 2216549 bytes, checksum: fa478c11726e2e9949d3ef39dfb34370 (MD5)

半导体磁性掺杂和p-型掺杂的第一性原理研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-02T02:17:45Z No. of bitstreams: 1 时洪亮_博士论文.pdf: 2279816 bytes, checksum: 147387269cb21bef3c6552c126ad37a0 (MD5)

First-principles study of UC2 and U2C3

The electronic structure and mechanical properties Of UC2 and U2C3 have been systematically investigated using first-principles calculations by the projector-augmented-wave (PAW) method. Furthermore, in order to describe precisely the strong on-site Coulomb repulsion among the localized U 5f electrons, we adopt the generalized gradient approximation +U formalisms for the exchange-correlation term. We show that our calculated structural parameters and electronic properties for UC2 and U2C3 are in good agreement with the experimental data by choosing an appropriate Hubbard U = 3 eV. As for the chemical bonding nature, the contour plot of charge density and total density of states suggest that UC2 and U2C3 are metallic mainly contributed by the 5f electrons, mixed with significant covalent component resulted from the strong C-C bonds. The present results also illustrate that the metal-carbon (U-C) bonding and the carbon-carbon covalent bonding in U2C3 are somewhat weaker than those in UC2, leading to the weaker thermodynamic stability at high temperature as observed by experiments.

基于SOI的微环谐振器研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-07T08:00:34Z No. of bitstreams: 1 基于SOI的微环谐振器研究.pdf: 5790574 bytes, checksum: 86f1490ce7ba4f3489d089e71623ffdd (MD5)

1.5 μm InGaAs 异变量子阱及InAs 单量子点光学性质的研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-02T02:21:53Z No. of bitstreams: 1 马珊珊--博士学位论文.pdf: 3541117 bytes, checksum: e1fd88257f0900d4c90a12f90c5e0376 (MD5)

First-principles study on the structural and electronic properties of ultrathin ZnO nanofilms

First-principles calculations; ZnO nanofilms; Electronic properties; Quantum effects； NANOBELTS; NANORINGS; WURTZITE; ENERGY Abstract: Using first-principles density-functional calculations, we have studied the structural and electronic properties Of Ultrathin ZnO {0001} nanofilms. The structural parameters, the charge densities, band structures and density of states have been investigated. The results show that there are remarkable charge transfers from Zn to O atoms in the ZOO nanofilms. All the ZOO nanofilms exhibit direct wide band gaps compared with bulk counterpart, and the gap decreases with increased thickness of the nanofilms. The decreased band gap is associated with the weaker ionic bonding within layers and the less localization of electrons in thicker films. A staircase-like density of states occurs at the bottom of conduction band, indicating the two-dimensional quantum effects in ZnO nanofilms.

基于二氧化硅阵列波导光栅的混合集成单纤三向器研制

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-07T08:03:04Z No. of bitstreams: 1 李俊一博士论文.pdf: 2831277 bytes, checksum: e2c0b239ef3998229c613fc3d4276206 (MD5)

InAs/GaAs量子点的非线性光学效应研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-07T00:55:16Z No. of bitstreams: 1 黄霞毕业论文.pdf: 1340687 bytes, checksum: 4ebcdabf0de9d75eab12b618ed9d495a (MD5)

The refractive nonlinearities of InAs/GaAs quantum dots above-bandgap energy

The third-order optical nonlinear refractive properties of InAs/GaAs quantum dots grown by molecular beam epitaxy have been measured using the reflection Z-scan technique at above-bandgap energy. The nonlinear refractive index and nonlinear absorption index of the InAs/GaAs quantum dots were determined for wavelengths from 740 to 777 nm. The measured results are compared with the nonlinear refractive response of several typical III-V group semiconductor materials. The corresponding mechanisms responsible for the large nonlinear response are discussed.

GaN 基垂直腔面发射激光器研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-08T13:07:49Z No. of bitstreams: 1 张江勇毕业论文.pdf: 1659784 bytes, checksum: eb70417dd2986217af3eaaba001bc8fd (MD5)

稀磁半导体（Ga,Mn)As 的超快磁光谱研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-07T02:59:47Z No. of bitstreams: 1 博士学位论文 － 朱永刚.pdf: 3575099 bytes, checksum: cb8ced7665a0624ff54bbfafa2be9c35 (MD5)

Tensile and compressive mechanical behavior of twinned silicon carbide nanowires

Molecular dynamics simulations with the Tersoff potential were used to study the response of twinned SiC nanowires under tensile and compressive strain. The critical strain of the twinned nanowires can be enhanced by twin stacking faults, and their critical strains are larger than those of perfect nanowires with the same diameters. Under axial tensile strain, the bonds of the nanowires are stretched just before failure. The failure behavior is found to depend on the twin segment thickness and the diameter of the nanowires. An atomic chain is observed for thin nanowires with small twin segment thickness under tension strain. Under axial compressive strain, the collapse of twinned SiC nanowires exhibits two different failure modes, depending on the length and diameter of the nanowires, i.e., shell buckling for short nanowires and columnar buckling for longer nanowires.

微纳光学结构增强GaN LED出光效率研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-13T08:02:10Z No. of bitstreams: 1 博士毕业论文_刘宏伟.pdf: 3404178 bytes, checksum: e5e1511387570aa5c92a4cc48df47e81 (MD5)