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71.
A new self-heating effect model for 4H-SiC MESFETs is proposed based
on a combination of an analytical and a computer aided design (CAD)
oriented drain current model. The circuit oriented expressions of
4H-SiC low-field electron mobility and in-complete ionization rate,
which are related to temperature, are presented in this model, which
are used to estimate the self-heating effect of 4H-SiC MESFETs. The
verification of the present model is made, and the good agreement
between simulated results and measured data of DC I-V curves with
the self-heating effect is obtained. 相似文献
72.
73.
激光二极管斜抽运的多增益段串接的液体激光器能够明显地提高激光光束质量、获得较高的输出功率.针对斜抽运子增益段工作时所涉及的流动、传热和壁面耦合,建立了计算子增益段流场热分布的流-热-固耦合模型,应用有限单元法完成了其瞬态流场热分布的数值模拟.该方法排除了不精确的换热系数对计算结果的影响,使得换热系数不再是计算的先决条件,而只是计算结果之一,并且为评价流道形状、流速、吸收系数等因素对流场热的影响,以及进一步改进和控制液体激光介质的流场热分布,提供了可靠的分析方法.数值模拟研究表明:换热系数是空间位置的函数, 相似文献
74.
This paper reports that the Raman spectra have been recorded on the
metal-organic chemical vapour deposition epitaxially grown GaN
before and after the Mn ions implanted. Several Raman defect modes
have emerged from the implanted samples. The structures around
182 cm-1 modes are attributed to the disorder-activated Raman scattering, whereas the 361 cm-1 and 660 cm-1 peaks are assigned to nitrogen vacancy-related defect scattering. One additional peak at 280 cm-1 is attributed to the vibrational mode of gallium vacancy-related defects and/or to disorder activated Raman scattering. A Raman-scattering study of lattice recovery is also presented by rapid thermal annealing at
different temperatures between 700 °C and 1050 °C on Mn implanted GaN epilayers. The behaviour of peak-shape change and
full width at half maximum (FWHM) of the A1(LO) (733 cm-1) and EH2 (566 cm-1) Raman modes are explained on the basis of implantation-induced lattice damage in GaN epilayers. 相似文献
75.
Fabrication and characterization of the normally-off N-channel lateral 4H–SiC metal–oxide–semiconductor field-effect transistors 下载免费PDF全文
In this paper, the normally-off N-channel lateral 4H–Si C metal–oxide–semiconductor field-effect transistors(MOSFFETs) have been fabricated and characterized. A sandwich-(nitridation–oxidation–nitridation) type process was used to grow the gate dielectric film to obtain high channel mobility. The interface properties of 4H–Si C/SiO_2 were examined by the measurement of HF I–V, G–V, and C–V over a range of frequencies. The ideal C–V curve with little hysteresis and the frequency dispersion were observed. As a result, the interface state density near the conduction band edge of 4H–Si C was reduced to 2 × 10~(11) e V~(-1)·cm~(-2), the breakdown field of the grown oxides was about 9.8 MV/cm, the median peak fieldeffect mobility is about 32.5 cm~2·V~(-1)·s~(-1), and the maximum peak field-effect mobility of 38 cm~2·V~(-1)·s~(-1) was achieved in fabricated lateral 4H–Si C MOSFFETs. 相似文献
76.
Atomic-layer-deposited Al_2O_3 and HfO_2 on InAlAs: A comparative study of interfacial and electrical characteristics 下载免费PDF全文
Al_2O_3 and HfO_2 thin films are separately deposited on n-type InAlAs epitaxial layers by using atomic layer deposition(ALD).The interfacial properties are revealed by angle-resolved x-ray photoelectron spectroscopy(AR-XPS).It is demonstrated that the Al_2O_3 layer can reduce interfacial oxidation and trap charge formation.The gate leakage current densities are 1.37×10~6 A/cm~2 and 3.22×10~6 A/cm~2 at+1V for the Al_2O_3/InAlAs and HfO_2/InAlAs MOS capacitors respectively.Compared with the HfO_2/InAlAs metal-oxide-semiconductor(MOS) capacitor,the Al_2O_3/InAlAS MOS capacitor exhibits good electrical properties in reducing gate leakage current,narrowing down the hysteresis loop,shrinking stretch-out of the C-V characteristics,and significantly reducing the oxide trapped charge(Q_(ot)) value and the interface state density(D_(it)). 相似文献
77.
Study of a double epi-layers SiC junction barrier Schottky rectifiers embedded P layer in the drift region 下载免费PDF全文
<正>This paper proposes a double epi-layers 4H—SiC junction barrier Schottky rectifier(JBSR) with embedded P layer (EPL) in the drift region.The structure is characterized by the P-type layer formed in the n-type drift layer by epitaxial overgrowth process.The electric field and potential distribution are changed due to the buried P-layer,resulting in a high breakdown voltage(BV) and low specific on-resistance(R_(on,sp)).The influences of device parameters,such as the depth of the embedded P+ regions,the space between them and the doping concentration of the drift region,etc.,on BV and R_(on,sp) are investigated by simulations,which provides a particularly useful guideline for the optimal design of the device.The results indicate that BV is increased by 48.5%and Baliga's figure of merit(BFOM) is increased by 67.9%compared to a conventional 4H-SiC JBSR. 相似文献
78.
利用Sentaurus搭建了碳化硅漂移阶跃恢复二极管(DSRD)与雪崩整形二极管(DAS)全电路仿真模型,研究了碳化硅等离子体器件在脉冲锐化方面的能力,并且通过器件内部等离子浓度分布解释了这两种器件实现脉冲锐化的机制。借助碳化硅DSRD可以将峰值超过千伏的电压脉冲的前沿缩短到300 ps;碳化硅DSRD与DAS的组合可以输出脉冲前沿在35 ps、峰值超过2 kV的电压脉冲。仿真与实验发现当触发脉冲与碳化硅DAS匹配时,可以实现快速开启后快速关断,得益于碳化硅DAS这种神奇现象,可以将峰值在两千伏以上脉冲的半高宽缩小到百皮秒量级;通过频谱分析发现脉冲经过DAS整形后,其最高幅值-30 dB对应的频谱带宽扩大了37倍,达到7.4 GHz。 相似文献
79.
Mn-doped graphene is investigated using first-principles calculations based on the density functional theory(DFT).The magnetic moment is calculated for systems of various sizes,and the atomic populations and the density of states(DOS)are analyzed in detail.It is found that Mn doped graphene-based diluted magnetic semiconductors(DMS)have strong ferromagnetic properties,the impurity concentration influences the value of the magnetic moment,and the magnetic moment of the 8×8 supercell is greatest for a single impurity.The graphene containing two Mn atoms together is more stable in the 7×7 supercell.The analysis of the total DOS and partial density of states(PDOS)indicates that the magnetic properties of doped graphene originate from the p–d exchange,and the magnetism is given a simple quantum explanation using the Ruderman–Kittel–Kasuya–Yosida(RKKY)exchange theory. 相似文献
80.
The effect of substrate doping on the flatband and threshold voltages of strained-Si/SiGe p metal-oxide semiconductor field-effect transistor (pMOSFET) has been studied. By physically deriving the models of the flatband and threshold voltages, which have been validated by numerical simulation and experimental data, the shift in the plateau from the inversion region to the accumulation region as the substrate doping increases has been explained. The proposed model can provide valuable reference to the designers of strained-Si devices and has been implemented in software for extracting the parameters of strained-Si MOSFET. 相似文献