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GaN的声表面波特性研究 总被引:1,自引:0,他引:1
采用金属有机物化学气相外延方法在(0001)面蓝宝石上生长了高质量、高阻的未掺杂(0001)面GaN薄膜。为精确测量GaN薄膜材料的声表面波特性,在GaN薄膜表面上沉积了金属叉指换能器,叉指换能器采用等叉指结构,叉指的数目为40对,叉指间距为15μm。采用脉冲法测量了声表面波在自由表面和金属表面上的速度,并通过计算得到了机电耦合系数(κ^2)。所测量的声表面波速度(ν)为5667m/s,机电耦合系数(κ^2)为1.9%。 相似文献
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采用一种新方法生长多层InGaN/GaN量子点,研究所生长样品的结构和光学特性。该方法采用了低温生长和钝化工艺,所以称之为钝化低温法。第一层InGaN量子点的尺寸平均宽度40nm,高度15nm,量子点密度为6.3×1010/cm2。随着层数的增加,量子点的尺寸也逐渐增大。在样品的PL谱测试中,观察到在In(Ga)As材料系中普遍观察到的量子点发光的温度特性---超长红移现象。它们的光学特性表明:采用钝化低温法生长的纳米结构中存在零维量子限制效应。 相似文献
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本文讨论了一个角形区域上边界条件有间断点的Laplace方程混合边值问题 的适定性,并给出了完整的解答. 相似文献
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We consider the singular Riemann problem for the rectilinear isentropic compressible Euler equations with discontinuous flux,more specifically,for pressureless flow on the left and polytropic flow on the right separated by a discontinuity x=x(t).We prove that this problem admits global Radon measure solutions for all kinds of initial data.The over-compressing condition on the discontinuity x=x(t) is not enough to ensure the uniqueness of the solution.However,there is a unique piecewise smooth so... 相似文献
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袁海荣 《数学物理学报(B辑英文版)》2019,(2)
We show existence of time-periodic supersonic solutions in a finite interval, after certain start-up time depending on the length of the interval, to the one space-dimensional isentropic compressible Euler equations, subjected to periodic boundary conditions. Both classical solutions and weak entropy solutions, as well as high-frequency limiting behavior are considered. The proofs depend on the theory of Cauchy problems of genuinely nonlinear hyperbolic systems of conservation laws. 相似文献
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