本文關(guān)鍵詞：高分辨電子顯微學(xué)方法及其在半導(dǎo)體材料研究中的應(yīng)用　出處：《中國(guó)科學(xué)院大學(xué)(中國(guó)科學(xué)院物理研究所)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 高分辨電子顯微學(xué) 解卷處理 GaN缺陷結(jié)構(gòu) 球差校正 非線性效應(yīng)

【摘要】：高分辨電子顯微學(xué)作為從原子尺度評(píng)價(jià)材料內(nèi)部結(jié)構(gòu)的最有力的實(shí)驗(yàn)手段之一,被廣泛應(yīng)用于各種材料的研究。但是,由于透射電鏡成像系統(tǒng)的像差和樣品厚度等的影響,高分辨像未必能反映正確的晶體結(jié)構(gòu)信息。為此往往需對(duì)高分辨像做細(xì)致的像襯分析或使用圖像處理方法等來提升圖像的分辨率以確定晶體結(jié)構(gòu)。隨著球差校正器的出現(xiàn)及廣泛使用,電鏡分辨率提升至0.1 nm甚至更高,多數(shù)情況下可分辨所有原子;并且球差系數(shù)的可調(diào)節(jié)性也為研究人員提供了更多的實(shí)驗(yàn)手段。然而,已有的像襯理論已難以對(duì)球差校正高分辨像作出很好的解釋,因此有必要對(duì)球差校正像的像襯理論及相應(yīng)的圖像處理方法進(jìn)行研究。本論文研究?jī)?nèi)容可分為兩部分:一部分介紹了高分辨電子顯微學(xué)及像解卷處理方法在Ga N薄膜缺陷結(jié)構(gòu)測(cè)定中的應(yīng)用;另一部分介紹了對(duì)球差校正高分辨像中非線性信息的研究工作。具體內(nèi)容包括:1.由200 kV普通電鏡拍攝的分辨率僅為約0.2 nm的高分辨像出發(fā),在原子尺度上測(cè)定了Ga N薄膜中多種缺陷的核心結(jié)構(gòu)。首先,利用解卷處理將原本不直接反映待測(cè)晶體結(jié)構(gòu)的實(shí)驗(yàn)像轉(zhuǎn)變?yōu)榻Y(jié)構(gòu)像,或稱解卷像,在此過程中使用了衍射振幅校正技術(shù),以減弱動(dòng)力學(xué)效應(yīng)對(duì)像襯的影響,提高解卷像的質(zhì)量;在解卷像上,間距僅為0.113 nm的Ga-N原子柱不能彼此完全分開,但仍可利用像襯分析技術(shù)分辨出這兩類原子;之后由解卷像推導(dǎo)出多種缺陷的原子組態(tài),包括層錯(cuò)、不全位錯(cuò)、60°全位錯(cuò)和60°分解位錯(cuò)等,確定了缺陷核心的類型、極性和形成機(jī)制等;其中多種位錯(cuò)核心的原子組態(tài)為首次由實(shí)驗(yàn)像獲得。2.結(jié)合透射交叉系數(shù)(TCC)理論和贗弱相位物體近似(PWPOA)理論對(duì)衍射圖(即高分辨像強(qiáng)度的傅里葉變換)中包含的非線性信息進(jìn)行了研究。利用PWPOA理論獲得出射波函數(shù)的表達(dá)式后,結(jié)合TCC理論得到了衍射圖中線性信息I_1(?)和非線性信息I_2(?)的解析表達(dá)式,對(duì)其強(qiáng)度和相位與樣品厚度和成像條件的關(guān)系進(jìn)行了分析;由于I_1(?)和I_2(?)分別為C_s和Δ1f_(eff)的奇函數(shù)和偶函數(shù),據(jù)此提出了一種分離球差校正像中線性和非線性信息的方法;并研究了非線性信息對(duì)球差校正高分辨像的衍射圖及解卷處理產(chǎn)生的影響。
[Abstract]:High resolution electron microscopy (HREM) is one of the most powerful experimental methods to evaluate the internal structure of materials from the atomic scale, and has been widely used in the study of various materials. Due to the aberration of the TEM imaging system and the thickness of the sample. High resolution image may not reflect correct crystal structure information. For this reason, it is necessary to make careful contrast analysis of high resolution image or to use image processing method to improve the resolution of the image to determine the crystal structure. The appearance and wide use of the device. The resolution of electron microscope is increased to 0.1 nm or higher, and in most cases all atoms can be distinguished. Moreover, the adjustable spherical aberration coefficient also provides more experimental means for researchers. However, the existing contrast theory is difficult to explain the spherical aberration correction high resolution image. Therefore, it is necessary to study the contrast theory of spherical aberration correction image and the corresponding image processing methods. In part, the application of high resolution electron microscopy and image deconvolution in the determination of defect structure of gan thin film is introduced. In the other part, the nonlinear information of spherical aberration correction in high resolution image is introduced. The specific contents include: 1. The resolution taken by 200 kV ordinary electron microscope is only about 0.2. High resolution image at nm. The core structures of various defects in gan thin films were measured at atomic scale. Firstly, the experimental images which did not directly reflect the crystal structure were transformed into structural images, or deconvolution images, using deconvolution processing. In order to reduce the influence of dynamic effect on image contrast and improve the quality of deconvolution image, the diffraction amplitude correction technique is used in this process. In unwinding images, the Ga-N atoms with a distance of only 0.113nm can not be separated completely from each other, but the two kinds of atoms can still be distinguished by contrast analysis. Then, the atomic configurations of various defects are deduced from the deconvolution image, including stacking faults, incomplete dislocations, 60 擄total dislocations and 60 擄decomposed dislocations, and the types, polarity and formation mechanism of defect cores are determined. The atomic configurations of many dislocation cores are obtained from experimental images for the first time. The diffraction patterns are obtained by combining the transmission cross coefficient (TCC) theory with the pseudo-weak phase object approximation PWPOA theory. The nonlinear information contained in the Fourier transform of high resolution image intensity is studied. The expression of the emissive wave function is obtained by using the PWPOA theory. Based on the TCC theory, the linear information in the diffraction pattern is obtained. ) and nonlinear information I _ 2s? The relationship between the intensity and phase, the thickness of the sample and the imaging condition is analyzed. ) and I2C? ) the odd function and even function of C _ s and 螖 _ 1F _ T _ f _ f _ f _ f _ f _ f respectively, and a method for separating the midline and nonlinear information of spherical aberration correction image is presented. The influence of nonlinear information on the diffraction pattern and deconvolution of spherical aberration correction high resolution image is studied.
【學(xué)位授予單位】：中國(guó)科學(xué)院大學(xué)(中國(guó)科學(xué)院物理研究所)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TN304

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相關(guān)期刊論文 前1條

1 李方華,范海福;用Sayre等式復(fù)原高分辨電子顯微象[J];物理學(xué)報(bào);1979年02期

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本文編號(hào)：1433207