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1.
材料的载流子浓度和迁移率是影响器件性能的关键因素, 变温Hall测试结果证明杂质掺杂AlGaN中的载流子浓度和迁移率随温度 降低而减小.然而极化诱导掺杂的载流子浓度和迁移率不受温度变化的影响.以准绝缘 的GaN体材料作为衬底, 在组分分层渐变的AlGaN中实现的极化诱导掺杂浓度 仅仅在1017 cm-3数量级甚至更低. 本研究采用载流子浓度为1016 cm-3量级的非有意n型掺杂GaN模板为衬底, 用极化诱导掺杂技术在分子束外延生长的AlGaN薄膜材料中实现了高 达1020 cm-3 量级的超高电子浓度. 准绝缘的体材GaN半导体作衬底时, 只有表面自由电子作为极化掺杂源, 而非有意掺杂的GaN模板衬底除了提供表面自由电子外,还能为极化电场 提供更多的自由电子"源", 从而实现超高载流子浓度的n型掺杂. 相似文献
2.
The equation of state and the structure and composition of neutron star matter are investigated in the density region 3.1 × 1011−2 × 1015g/cm3. Below the density 3.1 × 1011 g/cm3 the matter is a solid consisting of neutron-rich nuclei in a degenerate electron gas. At 3.1 × 1011g/cm3 neutrons start to drip out of the nuclei; as the density increases, the lattice spacing continuously decreases while the geometrical size of the nuclei only slightly increases, until at about 15 × 1013g/cm3 the nuclei disappear by coalescing into a homogeneous liquid in an almost continuous phase transition. The maximum proton number per nucleus is 40, which is obtained between the densities 1−2.5 × 1013g/cm3; after that the proton number decreases until at the solid-to-liquid phase boundary it is about 20. In the liquid-core region, muons appear at the density 20.5 × 1013g/cm3. 相似文献
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通过自洽求解一维Poisson-Schrdinger方程,模拟了AlGaN/GaN高电子迁移率晶体管在工作时等效外电场对AlGaN/GaN异质结沟道处二维电子气(2DEG)浓度的影响.分析了逆压电极化效应的作用,从正-逆压电极化现象出发,提出了逆压电极化模型.计算结果显示:逆压电极化明显影响2DEG性质,当Al组分x=0.3,AlGaN层厚度为20 nm时,不考虑逆压电极化,2DEG浓度为1.53×1013cm-2;当等效外电压分别为10和15V
关键词:
AlGaN/GaN高电子迁移率晶体管
Poisson-Schrdinger方程
逆压电极化模型
电流崩塌 相似文献
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We report the first successful optical pumping of cesium atoms to a state of high spin polarization with a CW dye laser tuned to the D1 second resonance line (4593 Å) of the cesium atom. Results of spin polarization versus laser power measurements for cells containing high-density cesium vapors (1013–1015 cm-3) plus mixtures of nitrogen (10–200 torr) and helium (≈1 atmosphere) gases are presented. These experiments have revealed unexpected limits to the spin polarization of dense alkali vapors. 相似文献
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The results of an investigation of the electromagnetic wave polarization, probing high-temperature laser plasma, as well as
spatial-temporal structure of the magnetic fields, electron density, current density, and electron drift velocity are presented.
To create the plasma, plane massive Al targets were irradiated with the second harmonic of a phoenix Nd laser at intensities
up to 5·1014 W/cm2. It was shown that the magnetooptical Faraday effect is the main mechanism responsible for the changing polarization of the
probing wave. Magnetic fields up to 0.4 MG with electron densities ∼1020 cm−3 were measured. Analysis of the magnetic field spatial distribution showed that the current density achieved the value ∼90
MA/cm2 on the laser axis. The radial structure of the magnetic field testified to the availability of the reversed current in the
laser plasma. The spatial and temporal resolutions in these experiments were equaled to ∼5 μsec and ∼50 psec, respectively.
Translated from Preprint No. 35 of the Lebedev Physics Institute, Moscow, 1993. 相似文献
9.
K. H. Park Y. T. Byun Y. Kim S. H. Kim S. S. Choi Y. Chung 《Optical and Quantum Electronics》1995,27(5):363-369
Al0.3Ga0.7As/GaAs/Al0.3Ga0.7As strip-loaded waveguides were fabricated using a broad-beam electron cyclotron resonance (ECR) ion source. It was found that a very smooth etching profile can be obtained by ECR ion etching and the etching rate of Al0.3Ga0.7As is 70 nm min-1. The propagation losses of strip-loaded type III–V compound semiconductor waveguides with various etching depths were studied by the Fabry-Perot cavity method. It was observed that the reflectance at the cleavage increases slightly with etching depth for TE polarization. The propagation loss is measured as 1.5 dB cm-1 for etching depth of 0.7 m, less than 1 dB cm-1 for 0.8 m, and 3.5 dB cm-1 for 1.1 m. 相似文献
10.
Abstract The shock adiabat for liquid xenon in the density range of 5.2–7.9 g/cm3 and pressure range of 8–70 GPa was investigated. The brightness temperature of a shock wave front from 5000 K to ?15,000 K, as well as the electrical conductivity behind the front from 4·103 to 1.2·105 1/Ohm m, were measured. X-ray technique was used to measure quasi-isentropic compression of liquid xenon up to ~13 g/cm3. The equations of state for liquid and solid phases of xenon were found. Anomalous behavior of xenon at p=8.37 g/cm3 was revealed, that is due to a structural transition. 相似文献
11.
Positron annihilation in ammonia gas at temperatures of ?19°C, 22,5°C, and 95°C in the density range 1.76 × 10?4 g/cm3 to 6.63 × 10?3 g/cm3 is investigated. 1Zeff for orthopositronium annihilation is 0.58 ± 0.04 Zeff/ Z for positrons not forming positronium varies from about 117 to 1329. 相似文献
12.
The total and specular light emitted at 2ω by a laser produced plasma (τ = 30 ps, λ = 1 μm) have been measured versus intensity (1012-1014 W/cm2), polarization and angle of incidence of the laser beam. The possibility for second harmonic to arise from resonant absorption, through a rippled critical surface, or from parametric decay instability is discussed. 相似文献
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Two polarization phenomena in Compton scattering by polarized electrons were investigated. In the first experiment, the rotation of the polarization plane of photons passing through magnetized iron and gadolinium was measured. This effect arises from a spin dependence of the Compton forward scattering amplitude. For 228 and 333 keV photons and iron absorbers, the observed rotation angles areφ 0=(3.90±0.57) ×10?3 rad · cm?2 and (4.75±0.58)×10?3 rad · cm?2, respectively. Secondly, the orientation of the photon polarization plane after scattering of unpolarized photons by polarized electrons was measured. This experiment tests time reversal invariance in quantum electrodynamics. No dependence of the polarization plane on the direction of the electron spin was found within 2×10?3. 相似文献
14.
S. Kistler P. Mittelstaedt W. Weyer 《Zeitschrift für Physik A Hadrons and Nuclei》1970,234(5):479-492
The equation of state for cold neutron matter has been derived for densities of 1012–1016 g/cm3. The energy density, the pressure and the velocity of sound have been calculated from nuclear forces by quantum mechanical many body techniques, which are well established in nuclear physics. It is found, that neutron matter is not bound and becomes superluminal and ultrabaric at densities of about 1015 g/cm3. In order to justify these strange results it is shown that the same physical assumptions which lead to the superluminal and ultrabaric behaviour in our calculation yield the same effects also in the lorentz invariant classical models of Zeldovich, Bludman and Ruderman. 相似文献
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This paper reports polarized spectral properties and energy levels of Cr3+ in KAl(MoO4)2 crystal. The absorption and emission cross sections are estimated as 3.72×10-20 cm2 at 669 nm and 2.74×10-20 cm-2 at 823 nm for σ-polarization, respectively. The energy levels of Cr3+ ion in KAl(MoO4)2 crystal were calculated based on the Tanabe-Sugano theory. It is suggested that Cr3+ ions occupy at an intermediate crystal field site in Cr3+:KAl(MoO4)2. 相似文献
16.
The sensitivities of pulsed photo-acoustic and photo-refractive (e.g., thermal lensing) techniques for the measurement of small absorptions in liquids have been evaluated both theoretically and experimentally. Electrostriction limits the sensitivity of both techniques, this limitation is less severe for the photo-refractive technique. The minimum absorption constants observed experimentally, for a 200-μm laser spot size in liquid N2, are 4 × 10-5 cm-1 for the photo-acoustic measurement and 6 × 10-7 cm-1 for the photo-refractive measurement. The calculated electrostrictive limits are 2 × 10-5 cm-1 and 7 × 10-11 cm-1, respectively. 相似文献
17.
氢气氛下生长的区熔硅(磷~1014/cm3)经镉比为10,总通量为(2.9—6.0)×1017n/cm2的中子辐照后,在77K,X波段观测到一种S=1/2的新EPR谱(标号为PK2)。geff值随(011)平面内磁场的角度关系呈三斜对称性。对应于缺陷在硅中一特定取向下的g张量主值及主轴相对于立方晶轴的方向余弦如下:g(±0.0004) n[100] n[010] n[001] g1关键词: 相似文献
18.
S. Banerjee G. Ravindra Kumar L.C. Tribedi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(2):295-300
We present studies of X-ray emission from aluminium under picosecond and femtosecond irradiation in the intensity range 1012-1015 W cm-2. We use a new and simple method to measure spectrally resolved absolute X-ray yields. It is shown that the X-ray yields can be obtained for arbitrary levels of X-ray flux. We
present details of the variation of the absolute yields as a function of wavelength, intensity, polarization and pulse duration
of the incident laser radiation. Electron temperatures in the keV range are observed at 1015 W cm-2 with femtosecond laser pulses.
Received 12 August 1999 and Received in final form 29 November 1999 相似文献
19.
The hyperfine structure of various absorption lines of molecular iodine with wavenumbers between 12980 and 13890 cm–1 has been resolved using Doppler-free polarization spectroscopy. The wavenumbers of theo-component of 17 rovibrational lines of I2 due to the transitionB
3
ou
+
–X1
g
+
with even rotational quantum numbers have been determined with an accuracy of 0.001 cm–1. A comparison of the centers of gravity of these 17 lines with the values of the iodine atlas of Gerstenkorn et al. yields a difference of
thus corroborating the data of the iodine atlas in the red region within limits of error. 相似文献
20.
V. M. Gordienko P. M. Mikheev V. S. Syrtsov 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(1):122-125
The dependence of the polarization plane rotation angle in the BaF2 crystal on the intensity of the femtosecond laser radiation with 0.62 μm wavelength in the ω = ω + ω ? ω process on cubical nonlinearity χ(3) is investigated. An anomalous increase in the efficiency of the cross-polarized radiation generation at I > 2 × 1012 W cm2 is observed for the first time. The 10% efficiency of the orthogonal component generation at the ~3 × 1012 W cm2 intensity is obtained. 相似文献