全文获取类型
收费全文 | 158篇 |
免费 | 2篇 |
专业分类
化学 | 44篇 |
晶体学 | 2篇 |
数学 | 11篇 |
物理学 | 36篇 |
无线电 | 67篇 |
出版年
2020年 | 2篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2013年 | 14篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2008年 | 2篇 |
2007年 | 7篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 9篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 8篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 8篇 |
1972年 | 2篇 |
1971年 | 4篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 2篇 |
1966年 | 1篇 |
1903年 | 1篇 |
排序方式: 共有160条查询结果,搜索用时 125 毫秒
1.
J. Hong E. S. Lambers C. R. Abernathy S. J. Pearton R. J. Shul W. S. Hobson 《Journal of Electronic Materials》1998,27(3):132-137
Dry etching of InGaP, AlInP, and AlGaP in inductively coupled plasmas (ICP) is reported as a function of plasma chemistry (BCl3 or Cl2, with additives of Ar, N2, or H2), source power, radio frequency chuck power, and pressure. Smooth anisotropic pattern transfer at peak etch rates of 1000–2000Å·min?1 is obtained at low DC self-biases (?100V dc) and pressures (2 mTorr). The etch mechanism is characterized by a trade-off between supplying sufficient active chloride species to the surface to produce a strong chemical enhancement of the etch rate, and the efficient removal of the chlorinated etch products before a thick selvedge layer is formed. Cl2 produces smooth surfaces over a wider range of conditions than does BCl3. 相似文献
2.
Y.K. Chen M.C. Wu W.S. Hobson S.J. Pearton A.M. Sergent M.A. Chin 《Photonics Technology Letters, IEEE》1991,3(5):406-408
High-power lattice-strained AlGaAs/InGaAs graded index separate-confinement heterostructure (GRINSCH) quantum-well lasers emitting at a 980-nm wavelength have been grown by organometallic vapor phase epitaxy (OMVPE) and fabricated with a self-aligned ridge-waveguide structure. Using a 3- mu m-wide and 750- mu m-long AR-HR coated laser, 30 mV of optical power was coupled into optical fibers with 28.6% efficiency. A dominating single-lobe far-field radiation pattern was obtained from a wedge-shaped ridge-waveguide laser for output power as high as 240 mW with a maximum output power of 310 mW.<> 相似文献
3.
Pearton S.J. Ren F. Katz A. Fullowan T.R. Abernathy C.R. Hobson W.S. Kopf R.F. 《Electron Devices, IEEE Transactions on》1992,39(1):154-159
The use of rapid isothermal processing (RIP) is detailed for each of the three annealing steps in the fabrication of heterostructure-based devices such as heterojunction bipolar transistors (HBTs). RIP can be used for the alloying of ohmic metal contacts, annealing of ion-bombarded regions for device isolation or parasitic capacitance reduction, and for conventional implant activation annealing. High-speed (f T=65 GHz) HBTs were achieved using RIP for all of the required heating steps. The authors compare the use of several types of silicon carbide-coated graphite susceptors for eliminating slip formation on 2- and 3-in-diameter GaAs wafers during high-temperature implant activation annealing 相似文献
4.
Fabrication and characteristics of high-speed implant-confined index-guided lateral-current 850-nm vertical cavity surface-emitting lasers 总被引:2,自引:0,他引:2
Dang G.T. Mehandru R. Luo B. Ren F. Hobson W.S. Lopata J. Tayahi M. Chu S.N.G. Pearton S.J. Chang W. Shen H. 《Lightwave Technology, Journal of》2003,21(4):1020-1031
Process technology of high-speed implant-apertured index-guide lateral-current-injection top dielectric-mirror quantum-well 850-nm vertical cavity surface-emitting lasers (VCSELs) has been developed. Oxygen and helium implantation for aperture definition and extrinsic capacitance reduction, dielectric mirror formation, p- and n-ohmic contact formation, VCSEL resistance, and thermal analysis were investigated. Employing this technology, GaAs/AlGaAs-based 850-nm VCSELs with small signal modulation bandwidths up to 11.5 Gb/s and an eye diagram generated at 12 Gb/s by a pseudorandom bit sequence of 2/sup 31/-1 were achieved. The bit-error rates were below 10/sup -13/. The threshold current is as low as 0.8 mA for 7-/spl mu/m-diameter current apertures and typical slope efficiencies of 0.45-0.5 mA/mW were obtained. 相似文献
5.
It is experimentally demonstrated that the image resolution from an in-line Fraunhofer hologram degrades appreciably when the centre of the diffraction pattern from a 5-bar resolution target is located asymmetrically in the hologram aperture. This effect is confirmed and analysed using calculated and experimentally measured images from holograms of a one-dimensional wire. Increasing asymmetry results in an increasing error in the measured linewidth, and a reduction of image resolution. A simple model based on average fringe contrast is used to predict this decrease in resolution with transverse object position. 相似文献
6.
A new approach to integrating hardware multiplication, division, and square-root is presented. We use a fully integrated control path which simultaneously reduces part of the redundant partial-remainder and performs a truncated multiplication of the next quotient or square-root digit by the divisor or square-root value. A separate (parallel) full precision iterative multiplier is used for partial remainder production. Strategic details of a radix-8 implementation are discussed. It is shown that a maximally redundant digit set is a viable choice for high performance in this case 相似文献
7.
Strain compensated InGaAs-GaAsP-InGaP laser 总被引:1,自引:0,他引:1
N.K. Dutta W.S. Hobson D. Vakhshoori H. Han P.N. Freeman J.F. de Jong J. Lopata 《Photonics Technology Letters, IEEE》1996,8(7):852-854
The performance characteristics of InGaAs-GaAsP-InGaP strain compensated laser emitting near 1 /spl mu/m are reported. The ridge waveguide lasers have room temperature threshold current of 18 mA and differential quantum efficiency of 0.45 W/A/facet. The linewidth enhancement factor is smaller and gain coefficient is larger for these strain compensated lasers compared to that for conventional strained layer laser. This may be due to higher effective compressive strain in the light emitting layer of these devices which reduces the effective mass. The observed larger gain coefficient is consistent with the measured larger relaxation oscillation frequency of these lasers compared to that for a conventional strained layer laser. 相似文献
8.
U. K. Chakrabarti S. J. Pearton W. S. Hobson C. R. Abernathy 《Plasma Chemistry and Plasma Processing》1993,13(2):333-350
Vinyl iodide (C2H3I) microwave discharges with additions of H2 and Ar are found to provide faster etch rates than conventional CH4/H2/Ar discharges for InP, InGaAs, GaAs, and AlGaAs. This is a result of the relatively high volatilities of indium, gallium, and aluminum iodide species. The etched features are smooth and anisotropic over a wide range of do self-biases (–150 to –350 V), process pressures (1–20mTorr), and microwave powers (150–500 W). The polymer that forms on the mask during the plasma exposure can be readily removed in O2 discharges. Electron spectroscopy for chemical analysis (ESCA) showed that the etched surfaces are slightly deficient in the group V elements under most conditions, but changes to the optical properties of the semiconductors are minimal. No defects are visible by transmission electron microscopy (TEM) in GaAs or InP samples etched at dc biases –250 V. 相似文献
9.
10.
The enzyme catalysed oxidation of ferrocene and some substituted ferrocenes to the corresponding ferricinium ions by hydrogen peroxide in the presence of native or immobilized horseradish peroxidase has been studied. Initial and maximum rates of oxidation have been determined. It was found that the oxidation was independent of the hydrogen peroxide concentration. The oxidation of ferrocene was effected also by horseradish peroxidase in a coupled system with glucose oxidase in the absence of any added hydrogen peroxide. 相似文献