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151.
A resonant cavity-enhanced (RCE) quantum dot (QD) field-effect transistor (RCEQDFET) is designed for single- photon detection in this paper. Adding distributed Bragg reflection (DBR) mirrors to the single-photon detector (SPD), we improve the light absorption efficiency of the SPD. The effects of the reflectivity of the mirrors, the thickness and light absorption coefficient of the absorbing layer on the detector's light absorption efficiency are investigated, and the resonant cavity is determined by using the air/semiconductor interface as the mirror on the top. Through analyzing the relationship between the refractive index of AlxGal_xAs and A1 component, we choose A1As/Alo.15Gao.85As as the material of the mirror on the bottom. The pairs of A1As/Alo.15Gao.85As film are further determined to be 21 by calculating the reflectivity of the mirror. The detector is fabricated from semiconductor heterostructures grown by molecular beam epitaxy. The reflection spectrum, photoluminescence (PL) spectrum, photocurrent response, and channel current of the detector are tested and the results show that the RCEQDFET-SPD designed in this paper has better performances in photonic response and wavelength selection. 相似文献
152.
采用分子束外延技术对δ掺杂GaAs/AlxGa1-xAs二维电子气(2DEG)样品进行了生长. 在样品生长过程中, 分别改变掺杂浓度(Nd)、空间隔离层厚度(Wd) 和AlxGa1-xAs中Al组分(xAl)的大小, 并在双温(300 K, 78 K)条件下对生长的样品进行了霍尔测量; 结合测试结果, 分别对Nd, Wd及xAl与GaAs/AlxGa1-xAs 2DEG的载流子浓度和迁移率之间的关系规律进行了细致的分析讨论. 生长了包含有低密度InAs量子点层的δ掺杂GaAs/AlxGa1-xAs 2DEG 样品, 采用梯度生长法得到了不同密度的InAs量子点. 霍尔测量结果表明, 随着InAs量子点密度的增加, GaAs/AlxGa1-xAs 2DEG的迁移率大幅度减小, 实验中获得了密度最低为16×108/cm2的InAs量子点样品. 实验结果为内嵌InAs量子点的δ掺杂GaAs/AlxGa1-xAs 2DEG的研究和应用提供了依据和参考.
关键词:
二维电子气
InAs量子点
载流子浓度
迁移率 相似文献
153.
We have obtained the parameter-phase diagram, which unambiguously defines the parameter region for the use of InAs/GaAs quantum
dot as two-level quantum system in quantum computation in the framework of the effective-mass envelope function theory. Moreover,
static electric field is found to efficiently prolong decoherence time. As a result, decoherence time may reach the order
of magnitude of milli-seconds as external static electric field goes beyond 20 kV/cm if only vacuum fluctuation is taken as
the main source for decoherence. Our calculated results are useful for guiding the solid-state implementation of quantum computing. 相似文献
154.
155.
带延时光学双稳装置分岔点处的光放大效应 总被引:1,自引:0,他引:1
调节在倍周期分岔第一个分岔点处的带延时光学双稳装置(OBD),对与系统谐振的光学小信号具有放大作用.本文对此作了理论分析. 相似文献
156.
Extremely low density InAs quantum dots (QDs) are grown by molecular beam droplet epitaxy. The gallium deposition amount is optimized to saturate exactly the excess arsenic atoms present on the GaAs substrate surface during growth, and low density InAs/GaAs QDs (4× 10^6 cm^-2) are formed by depositing 0.65 monolayers (MLs) of indium. This is much less than the critical deposition thickness (1.7 ML), which is necessary to form InAs/GaAs QDs with the conventional Stranski-Krastanov growth mode. The narrow photoluminescence linewidth of about 24 meV is insensitive to cryostat temperatures from IO K to 250K. All measurements indicate that there is no wetting layer connecting the QDs. 相似文献
157.
结合垂直腔面发射激光器(VCSEL)原理以及量子点增益特点,计算了有源层p掺杂结构的量子点VCSEL的材料增益和3 dB带宽,发现p掺杂结构可以大大提高频率特性.结合VCSEL激射条件和阈值特性,分析了对VCSEL结构的要求;分析了分布参数对频率特性的影响,对其外部封装提出了要求.设计了高频率响应的含氧化限制层的1.3 μm量子点VCSEL结构.
关键词:
量子点
垂直腔面发射激光器
微分增益
3 dB带宽 相似文献
158.
High-density and narrow size-distribution InAs quantum dots formed by a modified two-step growth
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We develop a modified two-step method of growing high-density and
narrow size-distribution InAs/GaAs quantum dots (QDs) by molecular
beam epitaxy. In the first step, high-density small InAs QDs are
formed by optimizing the continuous deposition amount. In the second
step, deposition is carried out with a long growth interruption for
every 0.1 InAs monolayer. Atomic force microscope images show that
the high-density ($\sim $5.9$\times $10$^{10}$\,cm$^{ - 2})$ good
size-uniformity InAs QDs are achieved. The strong intensity and
narrow linewidth (27.7\,meV) of the photoluminescence spectrum show
that the QDs grown in this two-step method have a good optical
quality. 相似文献
159.
酞菁锌的电子光谱和三阶非线性光学性质 总被引:2,自引:0,他引:2
用INDO/SDCI方法研究了酞菁锌的电子结构,紫外-可见光谱,三阶三线性光学系数及其色散效应。发现由于酞菁锌中Zn(Ⅱ)对γ的贡献很小使酞菁锌与酞菁的<γ>几乎相等。根据我们的计算结构对此进行了合理的解释。 相似文献
160.