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Scattering behaviours to the two-dimensional electron gasinduced by the Al composition fluctuation in AlxGa1-xNbarrier in AlxGa1-xN/GaN heterostructures 下载免费PDF全文
<正>This paper reports that cathodoluminescence(CL) measurements have been done to study the alloy fluctuation of the Al0.3Ga0.7N layer in Al0.3Ga0.7N/GaN heterostructures.The CL images and linescanning results demonstrate the existence of compositional fluctuation of Al in the Al0.3Ga0.7N barrier.A model using aδ-shape perturbation Hamilton function has been proposed to simulate the scattering probability of the two dimensional electron gases (2DEG) induced by Al composition fluctuation.Two factors,including conduction band fluctuation and polarization electric field variation,induced by the Al composition fluctuation have been taken into account.The scattering relaxation time induced by both factors has been estimated to be 0.31 ns and 0.0078 ns,respectively,indicating that the variation of the piezoelectric field is dominant in the scattering of the 2DEG induced by Al fluctuation. 相似文献
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Thin tungsten nitride (WNx) films were produced by reactive DC magnetron sputtering of tungsten in an Ar-N2 gas mixture. The films were used as Schottky contacts on AlGaN/GaN heterostructures. The Schottky behaviours of WNx contact was investigated under various annealing conditions by current-voltage (I-V ) measurements. The results show that the gate leakage current was reduced to 10-6 A/cm2 when the N2 flow is 400 mL/min. The results also show that the WNx contact improved the thermal stability of Schottky contacts. Finally, the current transport mechanism in WNx/AlGaN/GaN Schottky diodes has been investigated by means of I-V characterisation technique at various temperatures between 300 K and 523 K. A TE model with a Gaussian distribution of Schottky barrier heights (SBHs) is thought to be responsible for the electrical behaviour at temperatures lower than 523 K. 相似文献
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Optimization of a solar-blind and middle infrared two-colour photodetector using GaN-based bulk material and quantum wells 下载免费PDF全文
This paper calculates the wavelengths of the interband
transitions as a function of the Al mole fraction of AlxGa1-xN bulk material. It is finds that when the Al mole fraction is
between 0.456 and 0.639, the wavelengths correspond to the solar-blind
(250~nm to 280~nm). The influence of the structure parameters of
AlyGa1-yN/GaN quantum wells on the wavelength and absorption
coefficient of intersubband transitions has been investigated by
solving the Schr?dinger and Poisson equations self-consistently. The
Al mole fraction of the AlyGa1-yN barrier changes from
0.30 to 0.46, meanwhile the width of the well changes from 2.9~nm to
2.2~nm, for maximal intersubband absorption in the window of the air
(3~μm <λ <5~μm). The absorption coefficient of the
intersubband transition between the ground state and the first
excited state decreases with the increase of the wavelength. The
results are finally used to discuss the prospects of GaN-based bulk
material and quantum wells for a solar-blind and middle infrared
two-colour photodetector. 相似文献
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This paper investigates the behaviour of traffic flow in traffic systems with a new model based on the NaSch model and cluster approximation of mean-field theory. The proposed model aims at constructing a mapping relationship between the microcosmic behaviour and the macroscopic property of traffic flow. Results demonstrate that scale-free phenomenon of the evolution network becomes obvious when the density value of traffic flow reaches at the critical point of phase transition from free flow to traffic congestion, and jamming is limited in this scale-free structure. 相似文献
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Effects of Dislocation on High Temperature Transport Characteristics of Unintentionally Doped GaN 下载免费PDF全文
High temperature transport characteristics of unintentionally doped GaN have been investigated by means of high temperature Hall measurements from room temperature to 500^o C. The increment of electron concentration from room temperature to 500^o C is found to vary largely for different samples. The dispersion of temperature dependence of electron concentration is found to be directly proportional to the density of dislocations in GaN layers calculated by fitting the FWHM of the rocking curves in x-ray diffraction measurements (XRD). The buildup levels in persistent photoconductivity (PPC) are also shown to be directly proportionM to the density of dislocations. The correlation of XRD, Hall and PPC results indicate that the high temperature dependence of electron density in unintentional doped GaN is directly dislocation related. 相似文献
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以单层二硫化钼(MoS2)为代表的过渡金属硫族化合物半导体材料具有良好的光学、电学性质,近十年来引起了人们广泛的研究兴趣.合成高质量单层MoS2薄膜是科学研究及工业应用的基础.最近科研人员提出了盐辅助化学气相沉积生长单层薄膜的方法,大大提高了单层MoS2薄膜的生长速度及晶体质量.本文基于此方法,提出利用氯化钠(NaCl)的双辅助方法,成功制备了高质量的单层MoS2薄膜.光致发光(PL)谱显示其发光强度比无NaCl辅助生长的样品有了明显的提高.本文提出的NaCl双辅助生长方法为二维材料的大规模生长提供了思路. 相似文献