共查询到17条相似文献,搜索用时 500 毫秒
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采用扫描电镜中的电子背散射衍射(Electron Backscattering Diffraction,EBSD)技术,对硼掺杂的可动悬空硅薄膜和用于激光二极管(LED)的蓝宝石衬底上异质外延生长GaN层中的弹性应变区进行了测量.将菊池图的图像质量(IQ)和Hough转变强度,以及小角度晶界错配的统计数据作为应力敏感参数,研究了单晶材料系统中,微米~亚微米尺度的晶格畸变状态及局域弹性应变场.EBSD测试获得了硅薄膜窗口区域及LED的GaN外延层中的弹性应变分布. 相似文献
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本文采用电子背散射衍射(EBSD),测量纳米异质外延层的织构,及外延层与衬底的晶体取向匹配。测试的材料包括作为YBCO超导膜的过渡层、生长在强立方织构Ni-5at.%W(Ni-W)衬底上的La2Zr2O7(LZO)外延层,及LED器件中生长在蓝宝石衬底上的GaN过渡层和外延层。EBSD测量出LZO外延层具有旋转立方织构,显示出LZO与Ni-W衬底的面内取向(转动45°)及面外取向(沿[001]方向)的匹配关系。EBSD测量出GaN过渡层与蓝宝石衬底的面内取向(转动30°)的匹配关系,显示出由GaN过渡层的晶格畸变而引入的平行于外延生长方向的弹性应变梯度(约500 nm)。 相似文献
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采用化学方法腐蚀部分c面蓝宝石衬底,在腐蚀区域形成一定的图案,利用LP-MOCVD在经过表面处理的蓝宝石衬底上外延生长GaN薄膜.采用高分辨率双晶X射线衍射(DCXRD)、透射光谱分析GaN薄膜的晶体质量和光学质量.分析结果表明,GaN薄膜透射谱反映出的GaN质量与X射线双晶衍射测量的结果一致,即透射率越大,半高宽越小,结晶质量越好;对蓝宝石衬底进行前处理可以大大改善GaN薄膜的晶体质量和光学质量,其(0002)面及(1012)面XRD半高宽(FWHM)分别降低到208.80"及320.76" 相似文献
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采用化学方法腐蚀部分c面蓝宝石衬底,在腐蚀区域形成一定的图案,利用LP-MOCVD在经过表面处理的蓝宝石衬底上外延生长GaN薄膜.采用高分辨率双晶X射线衍射(DCXRD)、透射光谱分析GaN薄膜的晶体质量和光学质量.分析结果表明,GaN薄膜透射谱反映出的GaN质量与X射线双晶衍射测量的结果一致,即透射率越大,半高宽越小,结晶质量越好;对蓝宝石衬底进行前处理可以大大改善GaN薄膜的晶体质量和光学质量,其(0002)面及(1012)面XRD半高宽(FWHM)分别降低到208.80"及320.76" 相似文献
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采用化学方法腐蚀部分 c-面蓝宝石衬底,在腐蚀区域形成一定的图案,利用 LP-MOCVD 在此经过表面处理的蓝宝石衬底上外延生长 GaN 薄膜.采用高分辨率双晶X射线衍射(DCXRD)、光致发光光谱(PL)、透射光谱分析GaN薄膜的晶体质量和光学质量.分析结果表明,CaN 薄膜透射谱反映出的 CaN 质量与 X射线双晶衍射测量的结果一致,即透射率越大,半高宽越小,结晶质量越好;对蓝宝石衬底进行前处理可以大大改善GaN薄膜的晶体质量和光学质量,其(0002)面及(1012)面XRD半高宽(FWHM)分别降低到 208.80arcsec 及 320.76arcsec,而且其光致发光谱中的黄光带几乎可以忽略. 相似文献
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J.F. Luo Y. Ji T.X. Zhong Y.Q. Zhang J.Z. Wang J.P. Liu N.H. Niu J. Han X. Guo G.D. Shen 《Microelectronics Reliability》2006,46(1):178-182
An elastic strain field of the heteroepitaxial GaN layer grown on the sapphire substrate, containing a buffer interlayer, was measured using the electron backscatter diffraction (EBSD). Pattern qualities, Hough transforms and small misorientations of Kikuchi bands on EBSD patterns, as strain sensitive parameters and referred to diffraction intensities, were performed to evaluate the elastically distorted region within the sample. The elastic strain gradient parallel to the growth direction of GaN epilayers was mapped and a strain range from 100 nm to 200 nm was detected. 相似文献
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Effects on AlGaN/GaN high-electron-mobility transistor structure of a high-temperature AlN buffer on sapphire substrate have been studied by high-resolution x-ray diffraction and atomic force microscopy techniques. The buffer improves the microstructural quality of GaN epilayer and reduces approximately one order of magnitude the edge-type threading dislocation density. As expected, the buffer also leads an atomically flat surface with a low root-mean-square of 0.25 nm and a step termination density in the range of 108 cm?2. Due to the high-temperature buffer layer, no change on the strain character of the GaN and AlGaN epitaxial layers has been observed. Both epilayers exhibit compressive strain in parallel to the growth direction and tensile strain in perpendicular to the growth direction. However, an high-temperature AlN buffer layer on sapphire substrate in the HEMT structure reduces the tensile stress in the AlGaN layer. 相似文献
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Wilkinson AJ 《Journal of electron microscopy》2000,49(2):299-310
Two scanning electron microscope (SEM)-based diffraction techniques, i.e. electron channelling contrast imaging (ECCI) and electron back-scatter diffraction (EBSD) are used to study lattice defect and local elastic strain distributions in Si1-xGe(x) epilayers grown on Si substrates patterned with mesas. The ECCI technique allows the misfit dislocations to be imaged in bulk samples. The misfit dislocations caused plastic relaxation of the strain in planar regions between mesas and in the wider mesas. In the narrower mesas the removal of lateral constraint at the mesa side faces had reduced the stress sufficiently to suppress the propagation of dislocations parallel to the closely spaced side faces. The measurements of small changes in the positions of two zone axes in EBSD patterns caused by variations in the local strain field were used to determine the strains and rotations making up the generalized plane strain tensor describing the deformation in the long mesa structures. The strain sensitivity of the method was determined to be approximately +/- 2 x 10(-4). Distributions of strains and rotations across mesas of several dimensions are reported and differ significantly between mesa for which the mesas width to epilayer thickness is high and low. 相似文献
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The crystal quality, stress and strain of GaN grown on 4H-SiC and sapphire are characterized by high resolution X-ray diffraction(HRXRD) and Raman spectroscopy.The large stress in GaN leads to the generation of a large number of dislocations.The Raman stress is determined by the results of HRXRD.The position and line shape of the A1 longitudinal optical(LO) phonon mode is used to determine the free carrier concentration and electron mobility in GaN.The differences between free carrier concentration and electron mobility in GaN grown on sapphire and 4H-SiC are analyzed. 相似文献
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H. Lakner G. Brockt C. Mendorf A. Radefeld F. Scholz V. Härle J. Off A. Sohmer 《Journal of Electronic Materials》1997,26(10):1103-1108
The low pressure metalorganic vapor phase epitaxy growth of wurzite (Al, In, Ga)N heterostructures on sapphire substrates
is investigated by quantitative analytical scanning transmission electron microscopy techniques like atomic number (Z-) contrast
imaging and convergent beam electron diffraction (CBED). Especially (In, Ga)N quantum wells of different thicknesses as well
as superlattices were analyzed with respect to defects, chemical composition variations, interface abruptness and strain (relaxation)
effects. The interfaces in In0.12Ga0.88N/GaN quantum wells appear to be asymmetric. Additionally, we found composition variations of ΔxIn≥0.03 within the InGaN quantum wells. The application of electron diffraction techniques (CBED) yields quantitative information
on strain and relaxation effects. For the case of 17 nm thick InGaN quantum wells, we observed relaxation effects which are
not present in the investigated thin quantum wells of 2 nm thickness. The experimentally obtained diffraction patterns were
compared to simulations in order to get values for strain within the quantum wells. Additionally, the influence of dislocations
on the digression of superlattices is investigated. 相似文献
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A thin GaN LED film, grown on 2-inch-diameter sapphire substrates, is separated by laser lift-off. Atom force microscopy (AFM) and the double-crystal X-ray diffraction (XRD) have been employed to characterize the performance of Gan before and after the lift-off process. It is demonstrated that the separation and transfer processes do not alter the crystal quality of the GaN films obviously. InGaN/GaN multi-quantum-wells (MQW's) structure is grown on the separated sapphire substrate later and is compared with that grown on the conventional substmte under the same condition by using PL and XRD spectrum. 相似文献