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81.
Shizuo Fujita Tsuyoshi Tojyo Tetsu Yoshizawa Shigeo Fujita 《Journal of Electronic Materials》1995,24(3):137-141
Post-growth thermal annealing (e.g., 500°C, 30 min), is proposed as one of the promising techniques to realize and to improve
the quality of p-type ZnSe layers grown by metalorganic vapor phase epitaxy (MOVPE). The layers were grown at low temperature
(350°C) by photo-assisted MOVPE with doping nitrogen from tertiarybutylamine (t-BuNH2). The flow rate of t-BuNH2 was limited to be relatively low, in order to avoid heavy doping, with which as-grown layers exhibited electrically high-resistivity;
but the thermal annealing converted the layers to p-type. As the as-grown layers exhibited the stronger donor-to-acceptor
pair recombination lines or the weaker donor-bound excitonic emission (Ix) lines in photoluminescence, the annealed layers resulted in higher net acceptor concentration, which was 1 x 1017 cm−4 at the optimum conditions at present. 相似文献
82.
Guanghan Fan J Iwan Davies Nicholas Maung Maxwell J Parrott John O Williams 《Journal of Electronic Materials》1987,16(3):209-209
Epitaxial layers of ZnSe ranging in thickness from 5μm to 30 μm have been grown on GaAs (100) substrates over the temperature
range 240° C to 340° C by atmospheric pressure MOVPE employing dimethylzinc and hydrogen selenide. An optimum growth temperature
of 280 ± 5° C has been identified and when grown at this temperature the ZnSe epitaxial layers exhibit low resistivity (ρ
298
K
≤ 10 ohm · cm), a low compensation ratio (θ
298
K
= 0.27), a carrier mobility (μ
298
K
) of 250 ±10 cm
2
V
-1
s
-1
) and are
n
-type (
n
298
K
= 8.0 × 10
14
cm
-3
). The ratio of photoluminescence intensity measured at 298K and at 12 K is high (10
4
) and is dominated by a sharp emission due to excitons bound to neutral donors at 2.7956 eV. Mass spectrometric investigations
of the chemical reactions occurring inside the reactor in the presence of the GaAs substrate indicate significant surface-controlled
reactivity in the region of 280° C.
The online version of the original article can be found at 相似文献
83.
K. Hashimoto Y. Koide O. Tadanaga T. Oku N. Teraguchi Y. Tomomuea A. Suzuki Masanori Murakami 《Journal of Electronic Materials》1996,25(12):1823-1831
In order to explore a possibility of forming an intermediate semiconductor layer with low Schottky barrier by the conventional
deposition and annealing technique, the electrical properties of Cd and Te-based contacts on the nitrogendoped ZnSe substrates
have been investigated. Cd in the Cd/W contact reacted with the ZnSe substrate after annealing at temperatures above 250°C
and formed epitaxial Ccx}Zn1−xSe layers, leading to reduction of the “turn-on” voltage (VT) from about 11 to 6 V (here, a slash “/” between Cd and W means the deposition sequence). The reduction of the Vn} value by annealing at elevated temperatures was also observed for the Bi-Cd/W and In-Cd/W contacts. The average Cd composition
(x) in the Cdn}Zn1−xSe layers was measured to be larger than 0.9, which agreed with the values estimated from the calculated Cd-Zn-Se phase diagrams.
The ohmic behavior was strongly influenced by the thickness of the CdxZn1−xSe layer, the density of misfit dislocations formed at the interface between the Cdx Zn1−x Se and the ZnSe, and/or the total area of the Cd Zn. Se layers covering the ZnSe surface. The present result suggests that
formation of the large-areal CcxZn1−xSe layers with thin thickness is crucial to achieve further reduction of the VT value by the conventional deposition and annealing technique. Also, the VT reduction was not obtained for the Te/W contact even after annealing at temperatures close to 300°C, which was explained
to be due to absence of ternary ZnSe1−xTen intermediate layers. 相似文献
84.
The doping profile in semiconducting epitaxial layers is often deduced from the behavior of the capacitance of a Schottky
contact evaporated onto the surface of the layer as a function of the bias voltage. It is shown on the example of Au/ZnSe/GaAs
heterostructures that the heterojunction with the substrate in series with this Schottky contact leads to erroneous profiles,
if no special care is taken in the choice of the frequency used in measuring the capacitance. This frequency must be chosen
below the cutoff frequency which is apparent in the graphs of the capacitance vs the frequency. 相似文献
85.
ZnSe-GaAs heterovalent heterostructures were fabricated by metalorganic vapour phase epitaxy and characterized structurally
and electrically. A study on growth behaviour of GaAs on ZnSe revealed that either the 2-dimensional or the 3-dimensional
growth mode may occur depending on the growth conditions. This growth behaviour is applied to the construction of low-dimensional
structures. Successful fabrication of quantum well structures and GaAs islands buried into ZnSe is demonstrated by means of
X-ray diffraction and transmission electron microscopy. The electrical properties of the heterostructures are also described. 相似文献
86.
L. Wang J. H. Simmons M. H. Jeon R. M. Park C. J. Stanton 《Journal of Electronic Materials》1996,25(2):177-181
In this paper, nonlinear optical properties of CdxZn1-xSe/ZnSe (x = 0.2) multiple quantum wells were studied by low temperature steady-state and transient photoluminescence at high
excitation densities. The biexciton transition was observed on the low energy side of the exciton transition. Based on the
characteristics of stimulated emission observed in similar structures, we suggest the biexciton transition as the mechanism
for stimulated emission. Optical degradation was also studied by room temperature photoluminescence using femtosecond laser
pulses as the excitation source. The results confirm the formation of nonradiative recombination centers with a saturating
degradation effect after about 10 min of exposure. 相似文献
87.
Highly conductivep-type ZnSe layers have been grown on GaAs substrates by vapor phase epitaxy in an open system. Iodine and hydrogen were used
as transport agents. The ZnSe layers exhibited a conductivity up to 50 (Ωcm)−1 and a carrier concentration of 4 × 1018 cm−3 together with a Hall mobility of 100 cm2/Vs. These values are the highest ones reported so far. Low-temperature photoluminescent spectra indicated new bound excitons.
Electroluminescent metal/p-ZnSe/n-GaAs heterojunctions exhibited blue emission at 2.68 eV dominating the spectra. 相似文献
88.
L. H. Kuo L. Salamanca-Riba J. M. Depuydt H. Chèng J. Qiu 《Journal of Electronic Materials》1994,23(3):275-281
Nitrogen doped ZnSe/GaAs heterostructures grown at 150 and 250°C were studied by transmission électron microscopy (TEM). The
density of threading dislocations and the interfacial dislocation structure in ZnSe/GaAs heterostructures are related to the
N-doping concentration. In addition, in-situ TEM heating studies show that Frank partial dislocations formed below critical
thickness in N-doped ZnSe/GaAs are the sources for nucleation of a regular array of misfit dislocations at the ZnSe/GaAs interface.
By the dissociation of the Frank partial dislocations and interaction reactions between the dislocations, the 60° misfit dislocations
form. The Frank partial dislocations bound stacking faults which usually form in pairs at the film/substrate interface. The
density of stacking faults increases with increasing N-doping concentration. Thus, at high N-doping levels, the dislocation
nucleation sources are close together and not all of the Frank partial dislocations dissociate, so that a high density of
threading dislocations results in samples with high N-doping concentrations. The high density of threading dislocations in
the ZnSe film are found to be associated with a reduction or saturation of the net carrier density. 相似文献
89.
In situ optical reflection measurement was employed to study surface processes during the MOVPE growth of ZnSe films under an alternate supply of diethylzinc (DEZn) and dimethylselenide (DMSe) using H2 and/or N2 as carrier gases. We have found that the time-dependent reflection signal exhibits a unique saw-toothed pattern during the DEZn supply, which is attributed to the adsorption and structural change of the DEZn. In contrast, the influence of DMSe on the time-dependent signal appears to be rather marginal. A growth mechanism is proposed based on these experimental results, through which the important role of ambient hydrogen is discussed. 相似文献
90.
Mitsuru Funato Hiroaki Kitani Shizuo Fujita Shigeo Fujita 《Journal of Electronic Materials》1996,25(2):217-222
The effects of GaAs buffer layer and lattice-matching on the nature of deep levels involved in Zn(S)Se/GaAs heterostructures
are investigated by means of deeplevel transient spectroscopy (DLTS). The heterojunction diodes (HDs) where nZn(S)Se is grown
on p+-GaAs by metalorganic vapor phase epitaxy are used as a test structure. The DLTS measurement reveals that when ZnSe is directly
grown on a GaAs substrate, there exist five electron traps A-E at activation energies of 0.20, 0.23, 0.25, 0.37, and 0.53
eV, respectively. Either GaAs buffer layer and lattice-matching may reduce the incorporation of traps C, D, and E, implying
that these traps are ascribed to surface treatment of GaAs substrate and to lattice relaxation. Concentration of trap B, which
is the most dominant level, is proportional to the donor concentration. However, in the ZnSSe/GaAs sub. HD, another trap level,
instead of trap B, locates at the almost same position as that of trap B, and it shows anomalous behavior that the DLTS peak
amplitude changes drastically as changing the rate windows. This is explained by the defect generation through the interaction
between sulfide and a GaAs substrate surface. For the trap A, the concentration is a function of donor concentration and lattice
mismatch, and the origin is attributed to a complex of donor induced defects and dislocations. 相似文献