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排序方式: 共有142条查询结果,搜索用时 15 毫秒
91.
A photovoltaic quantum dot infrared photodetector with InAs/GaAs/AIGaAs structures is reported. The detector is sensitive to normal incident light. At zero bias and 78K, a clear spectral response in the range of 2-7μm has been obtained with peaks at 3.1, 4.8 and 5.7μm. The bandgap energies of GaAs and Al0.2Ga0.8As at 78K are calculated and the energy diagram of the transitions in the Quantum-Dot Infrared Photodetector (QDIP) is given out. The photocurrent signals can be detected up to 110 K, which is state-of-the-art for photovoltaic QDIP, The photovoltaic effect in our detector is a result of the enhanced band asymmetry as we design in the structure. 相似文献
92.
We demonstrate surface emitting distributed feedback quantum cascade lasers emitting at wavelengths from 8.1 μm at 90 K to 8.4 μm at 210 K. The second?order metalized grating is carefully designed using a modified coupled-mode theory and fabricated by contact lithography. The devices show single mode behavior with a side mode suppression ratio above 18 dB at all working temperatures. At 90 K, the device emits an optical power of 101 mW from the surface and 199 mW from the edge. In addition, a double-lobe far-field pattern with a separation of 2.2° is obtained in the direction along the waveguide. 相似文献
93.
94.
Spacer layer thickness fluctuation scattering in a modulation-doped Al<sub>x</sub>Ga<sub>1-x</sub>As/GaAs/Al<sub>x</sub>Ga<sub>1-x</sub>As quantum well 下载免费PDF全文
We theoretically study the influence of spacer layer thickness fluctuation(SLTF) on the mobility of a twodimensional electron gas(2DEG) in the modulation-doped Al x Ga 1 x As/GaAs/Al x Ga 1 x As quantum well.The dependence of the mobility limited by SLTF scattering on spacer layer thickness and donor density are obtained.The results show that SLTF scattering is an important scattering mechanism for the quantum well structure with a thick well layer. 相似文献
95.
利用固源分子束外延(MBE)的方法经SK模式自组装生长由多层InAs/GaAs量子点组成的柱形岛.具体分析了GaAs间隔层厚度,生长停顿时间以及InAs淀积量对发光峰波长的影响.原子力显微镜(AFM)结果显示柱形岛表面的形状和尺寸都比较均匀;室温下不同高度的柱形岛样品的发光波长分别达到1.32和1.4μm,而单层量子点的发光波长仅为1.1μm,充分说明了量子点高度对发光波长的决定性影响,这为调节量子点发光波长提供了一种直观且行之有效的方法.
关键词:
柱形岛
生长停顿
间隔层厚度
PL谱 相似文献
96.
Indium-Induced Effect on Polarized Electroluminescence from InGaN/GaN MQWs Light Emitting Diodes 下载免费PDF全文
Polarization-resolved edge-emitting electroluminescence (EL) studies of In GaN/GaN MQWs of wavelengths from near-UV (390nm) to blue (468nm) light-emitting diodes (LEDs) are performed. Although the TE mode is dominant in all the samples of InGaN/GaN MQW LEDs, an obvious difference of light polarization properties is found in the InGaN/GaN MQW LEDs with different wavelengths. The polarization degree decreases from 52.4% to 26.9% when light wavelength increases. Analyses of band structures of InGaN/GaN quantum wells and luminescence properties of quantum dots imply that quantum-dot-like behavior is the dominant reason for the low luminescence polarization degree of blue LEDs, and the high luminescence polarization degree of UV LEDs mainly comes from QW confinement and the strain effect. Therefore, indium induced carrier confinement (quantum-dot-like behavior) might play a major role in the polarization degree change of InGaN/GaN MQW LEDs from near violet to blue. 相似文献
97.
We report on the realization of GaAs/AlGaAs quantum cascade lasers with an emission wavelength of 9.1 μm above the liquid nitrogen temperature. With optimal current injection window and ridge width of 24 and 60μm respectively, a peak output power more than 500mW is achieved in pulsed mode operation. A low threshold current density Jth = 2.6 kA/cm^2 gives the devices good lasing characteristics. In a drive frequency of i kHz, the laser operates up to 20% duty cycle. 相似文献
98.
分别采用二种不同方法测量分子束外延(MBE)生长GaAs/In0.2Ga0.8As单量子阱结构的导带不连续量ΔEc:1) 考虑样品界面电荷修正的电容-电压(C-V)分布;2) 量子阱载流子热发射产生的电容瞬态(DLTS).C-V测得的ΔEc=0.227eV,大约相当于89% ΔEg.DLTS测得的ΔEc=0.229eV,大约相当于89.9% ΔEg.结果
关键词: 相似文献
99.
利用固源分子束外延设备生长出InAs/InAlAs/InP(001)纳米结构材料, 探讨了As压调制的InAlAs超晶格对InAs纳米结构形貌的影响. 结果表明, As压调制的InAlAs超晶格能控制InAs量子线的形成, 导致高密度均匀分布的量子点的生长. 结果有利于进一步理解量子点形貌控制机理. 分析认为, InAs纳米结构的形貌主要由InAlAs层的各向异性应变分布和In吸附原子的各向异性扩散所决定. 相似文献
100.
A 10.7μm quantum cascade detector based on lattice matched InGaAs/InAlAs/InP is demonstrated and characterized in terms of responsivity, resistivity and detectivity. The device operates in the 8 14μm atmospheric window up to 140 K and shows a peak reponsivity of 14.4mA/W at 78K. With a resistance-area product value of 159Ωcm^2, the Johnson noise limited detectivity D^*J is 2.8 × 10^9 Jones (cmHz^1/2W^-1) at 78K. 相似文献