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11.
K. A. Jones R. T. Lareau T. Monahan J. R. Flemish R. L. Pfeffer R. E. Sherriff C. W. Litton R. L. Jones C. E. Stutz D. C. Look 《Journal of Electronic Materials》1995,24(11):1641-1648
Symmetric δ-doped InGaP and AlGaAs PHEMT structures have been grown by organometallic vapor phase epitaxy with properties
that approach those of MBE grown AlGaAs structures. The 300 and 77K carrier concentrations for the InGaP PHEMT were 2.72 and
2.56 × 1012 cm2
−2 and the mobilities were 5,920 and 22,000 cm2
2/V.s. These excellent values suggest that problems associated with switching the anion at the channel heterojunction have
been overcome. The corresponding values for the AlGaAs PHEMT were 2.51 and 2.19 × 1012 cm2
−2 and 6,500 and 20,400 cm2/V.s. The uniformity in the indium concentration in the InGaAs layer as determined by photoluminescence, photoreflection,
double crystal x-ray diffraction, and Rutherford backscattering was found to be good, but the percent In in the AlGaAs pseudo-morphic
high electron mobility transistor (PHEMT) was less than that in the InGaP PHEMT even though the programmed values were the
same. The uniformity in the doping distribution as determined by secondary ion mass spectroscopy and electrochemical capacitance-voltage
measurements was found to be good, but it decreased with distance from the center of the susceptor. Also, most of the dopants
in the δ-doped InGaP and AlGaAs layers were activated. 相似文献
12.
We study the technology of local anodic oxidation (LAO) by the AFM tip applied to semiconductor heterostructures with two-dimensional electron gas. The aim is to design mesoscopic rings with persistent current and one subband occupied. For this purpose the need is to oxidize narrow lines that represent energy barriers high enough. Using the electrostatic model, we explain the electric field distribution in the system tip-sample just before LAO starts. We study the influence of the conductivity of the cap layer on LAO and explain the origin of the saddle-like profile lines, observed in the experiment. Using Monte Carlo simulation we show that the carrier redistribution in the system with LAO energy barriers effectively lowers the barrier height. In the experimental part we have grown InGaP/AlGaAs/GaAs heterostructures by organometalic vapor phase epitaxy with an active layer only 31 nm below the surface. We have prepared oxide lines on the heterostructures by LAO and characterized them by the temperature-dependent transport measurement. 相似文献
13.
Tirthajyoti Sarkar 《Microelectronics Journal》2007,38(2):285-298
Optical modulation by varying the intensity, wavelength, or switching time can dynamically alter the performance parameters of direct optically controlled power semiconductor device. Understanding the effect of optical parameters on these parameters from a first principle approach is necessary for making optimal design choices and gaining design insights. We focus on performance parameters whose variations with direct optical modulation have not been reported previously for a power semiconductor such as switching times and on-state resistance. We carry out analytical modeling and two-dimensional (2D) finite-element simulations for a GaAs/AlGaAs based superjunction lateral optically controlled power transistor that has been fabricated and successfully tested for high-voltage capability. It is shown that optical power density can modulate on-state resistance and more importantly the trade-off curve between breakdown voltage and on-state resistance. A closed-form analytical equation relating switching times with optical parameters via logarithmic function is derived and the nonlinear variation of on-state resistance and switching time with optical wavelength is illustrated. We also derive the analytical expression for power device rise time as a function of optical signal rise time and show that they are related by Lambert's W-function with exponential coefficients. 相似文献
14.
The photoluminescence (PL) at low temperature of three delta-doped AlGaAs/GaAs heterostructures is investigated under continuous and pulsed excitations. The PL under continuous excitations allows the identification of the trapping centres and probes the carrier's transfer to the GaAs channel. The time-resolved photoluminescence (TRPL) inquires about carrier dynamics and gives radiative lifetimes of different levels. The DX level shows two time constants of the intensity decay relating the splitting of the valence band under impurity strains which reduce the crystal symmetry. The two time constants evolve with temperature and exhibit an increase near T=50 K. 相似文献
15.
V. Frese G. K. Regel H. Hardtdegen A. Brauers P. Balk M. Hostalek M. Lokai L. Pohl A. Miklis K. Werner 《Journal of Electronic Materials》1990,19(4):305-310
The MOCVD of AlGaAs and GaAs from coordinatively saturated group III source materialsi.e. 1–3-dimethyl-aminopropyl-l-galla-cyclohexane ((C5H10)Ga(C2N(CH3
2) and the corresponding Al compound) was investigated. It was demonstrated that these precursors, which are inherently free
of alkoxy contamination, are suitable for epitaxial growth of GaAs layers and structures of GaAs/AlGaAs. For comparison, data
achieved with TEA (Al(C2H5)3) or TiBA (Ali(C4H9)3) and TEG (Ga(C2H5)3) are presented. A basic finding of this study is that due to the low thermal stability of TEA, TiBA and TEG the layers grown from these compounds suffer from insufficient homogeneity of layer thickness and composition.
In contrast, the coordinatively saturated compounds show a reactivity suitable for large area growth. Additionally, intrinsic
impurity (N, C) uptake appears to be low and electrical as well as PL data show the satisfactory quality of GaAs and AlGaAs
layers grown from this new type of precursors. Specifically, a reduction of oxygen incorporation compared to growth from the
standard trialkyls is indicated by PL measurements on layers grown at different temperatures. 相似文献
16.
A dilute mixture of CCl4 in H2 has recently been shown to be a suitable carbon doping source for obtainingp-type GaAs grown by metalorganic chemical vapor deposition (MOCVD) with carbon acceptor concentrations in excess of 1 × 1019cm−3. To understand the effect of growth parameters on carbon incorporation in CCl4 doped Al
x
Ga1−x
As, carbon acceptor concentration was studied as a function of Al composition, growth temperature, growth rate, and CCl4 flow rate using electrochemical capacitance-voltage profiling. The carbon incorporation as a function of Al composition,
growth temperature and CCl4 flow rate was also measured by secondary ion mass spectroscopy (SIMS). All layers were grown by low pressure MOCVD using
TMGa and TMAl as column III precursors, and 100% AsH3 as the column V source. Increased Al composition reduced the dependence of carbon concentration on the growth temperature.
Reduced growth rate, which resulted in substantially decreased carbon acceptor concentrations in GaAs, had an insignificant
effect on the carrier concentration of Al0.4Ga0.6As. A linear relationship between hole concentration and CC14 flow rate in AlxGa1−x
As for 0.0 ≤x ≤ 0.8 was observed. These results are interpreted to indicate that adsorption and desorption of CCl
y
(y ≤ 3) on the Al
x
Ga1-x
As surface during crystal growth plays an important role in the carbon incorporation mechanism. 相似文献
17.
Rong-Ting Huang Dumrong Kasemset N. Nouri C. Colvard D. Ackley 《Journal of Electronic Materials》1989,18(5):603-609
A unique multi-wafer OMVPE reactor with capability to produce atomic-layer abrupt-ness is demonstrated. Uniform GaAs and AlGaAs epitaxial layers were grown on four two-inch wafers or one three- or four-inch wafer. Thickness variation across a three-inch wafer was less than ±2%, while the variation of Al solid composition was less than ±1%. Multiple AlGaAs/GaAs quantum wells ranging in size from 10Å to 140Å were grown with heterointerface roughness less than one monolayer. The electrical properties of HEMT device were studied. Variations of sheet carrier concentration and electron mobility were ±6% and ±5% respectively across a three-inch wafer. The carrier con-centration profile, mobility spectrum and device characteristics of DH-HEMT are also presented. These results indicate that this OMVPE reactor can grow good device struc-tures for microwave and millimeter-wave power device applications. 相似文献
18.
报道了一种在倍增区引入AlxGa1-xAs带隙梯度结构的谐振腔增强型雪崩光探测器,并提出优化其后工艺制作的新方法.通过将Al0.4Ga0.6As(28 nm)一Al0.2Ga0.8As(10 nm)-GaAs(50 nm)带隙梯度结引入雪崩探测器的高场区,可以实现对探测器噪声和频率响应两个主要性能的优化.数值仿真表明,该结构探测器具有较小的噪声(有效离化系数为0.1),约33 GHz的3 dB带宽(增益为5),在增益为15时可获得420 GHz的增益带宽积.在实际的后工艺制作中,提出使用苯并环丁烯树脂进行InP/空气隙DBR反射镜与雪崩探测器结构粘合的方法,简化了工艺流程.摘要: 相似文献
19.
Dance Spirkoska Anna Fontcuberta i Morral Joseph Dufouleur Qiushi Xie Gerhard Abstreiter 《固体物理学:研究快报》2011,5(9):353-355
Modulation doped AlGaAs/GaAs core–shell nanowire structures were grown by molecular beam epitaxy. A Si delta‐doping was introduced in the AlGaAs shell around the {110} facets of the GaAs core. The wires are typically highly resistive at low temperatures. However, they show a pronounced persistent photoconductivity effect indicating activation of free carriers from the delta‐doped shell to the GaAs core. The n‐type character of the channel is demonstrated by applying a back‐gate voltage. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
20.
The Electron Paramagnetic Resonance (EPR) and Optically-Detected Magnetic Resonance (ODMR) work on Si-donors in Al
x
Ga1-
x
As is reviewed in the context of the shallow-deep bistability (DX) problem. Three donor states are important. Little work has been published on donors tied to theT-minimum. However, there are many results forX-donors. In AlAs/GaAs heterostructures, well-resolved spectra reveal a donor state comprised of independentX
x
andX
y
valleys with theXz valley unpopulated due to the hetero-epitaxial strain. As Al mole fraction decreases, intervalley coupling is evident from
the line positions and linewidths. The published attempts to observe and identify the deep (relaxed) state are inconclusive.
Some suggestions for future work are presented. 相似文献