【摘要】：隨著慣性約束核聚變(Inertial Confinement Fusion,ICF)工程的發(fā)展,人們對(duì)KDP晶體的需求、質(zhì)量、生長(zhǎng)速度等都提出了更高的要求,可以概括為"快速、大尺寸、高質(zhì)量"。"快速":可以提供工程上所需要的KDP晶片數(shù)量,縮短生長(zhǎng)周期,降低成本。"大尺寸":可以滿足ICF系統(tǒng)裝置中對(duì)晶體尺寸的要求。"高質(zhì)量":可以達(dá)到ICF裝置對(duì)KDP晶體性能要求的指標(biāo),如高的激光損傷閾值、高的透過率、高的光學(xué)均勻性等。近年來,人們對(duì)KDP晶體的研究主要在生長(zhǎng)工藝、光學(xué)質(zhì)量、晶體結(jié)構(gòu)等方面。我們認(rèn)為要從根本上提高KDP晶體的生長(zhǎng)速度、光學(xué)性能,應(yīng)該對(duì)晶體生長(zhǎng)的微觀形貌以及生長(zhǎng)機(jī)制進(jìn)行研究。作為經(jīng)典的水溶液生長(zhǎng)晶體,溫度、過飽和度、雜質(zhì)、pH等介質(zhì)環(huán)境對(duì)KDP晶體的生長(zhǎng)習(xí)性、光學(xué)質(zhì)量等都有著重要的影響。因此,本文主要選擇通過改變生長(zhǎng)溶液的飽和溫度、過飽和度、pH值,以及通過摻雜金屬離子雜質(zhì)、有機(jī)添加劑的方式,來研究各種介質(zhì)因素對(duì)KDP晶體生長(zhǎng)臺(tái)階的微觀形貌、生長(zhǎng)速度的影響,對(duì)不同條件下生長(zhǎng)所得的晶體進(jìn)行激光損傷閾值的測(cè)試,并對(duì)其影響機(jī)理進(jìn)行了初步的探討研究。本論文的主要內(nèi)容如下:1.在不同飽和溫度的溶液,不同的過飽和度下生長(zhǎng)了 KDP晶體,測(cè)試了晶體的激光損傷閾值。利用原子力顯微鏡觀察了不同條件下KDP晶體的表面微觀形貌。通過激光偏振干涉系統(tǒng)實(shí)時(shí)測(cè)量了在不同溫度下,KDP晶體的生長(zhǎng)速度與過飽和度之間的關(guān)系。實(shí)驗(yàn)結(jié)果表明:在低溫度區(qū)域(~35℃C)下,晶體表面生長(zhǎng)臺(tái)階在低過飽和度(σ=0.01)、中間過飽和度(σ=0.05)以及高過飽和度(σ=0.08)下,都出現(xiàn)了聚并升高的現(xiàn)象,宏臺(tái)階包含基本臺(tái)階的個(gè)數(shù)分別平均為21、22、59個(gè)。與此相對(duì)應(yīng)的,臺(tái)階的斜率也在這三個(gè)過飽和度下出現(xiàn)了峰值,分別為9.26×10-3、9.64×10-3、8.47×10-3。另外,在高過飽和度σ=0.08時(shí),晶體表面出現(xiàn)"樹枝狀"臺(tái)階,我們認(rèn)為可能與臺(tái)階上存在著Ehrlich-Schwoebel(E-S)勢(shì)壘有關(guān)。在中溫度區(qū)域(~45℃C、55℃C)下,晶體表面的臺(tái)階聚并程度都在σ=0.04時(shí)出現(xiàn)峰值,此時(shí),在45℃C下生長(zhǎng)的臺(tái)階的高度要略高于55℃C的情況。在晶體生長(zhǎng)過程中,臺(tái)階的斜率都在中間過飽和度區(qū)域出現(xiàn)一個(gè)峰值,45℃C時(shí),斜率的峰值出現(xiàn)在σ=0.06時(shí),而55℃C時(shí)峰值對(duì)應(yīng)的過飽和度要低,在σ=0.04時(shí)。這兩個(gè)峰值位置所對(duì)應(yīng)的臺(tái)階寬度都是急劇降低的。在高過飽和度下,臺(tái)階的聚并程度和臺(tái)階斜率都隨過飽和度的升高而增大,其中55℃C時(shí)更為顯著。在高溫度區(qū)域(~65℃C)下,晶體表面生長(zhǎng)臺(tái)階的聚并程度和臺(tái)階斜率都隨著過飽和度的升高呈現(xiàn)出先增大后減小的趨勢(shì),都在過飽和度σ=0.03時(shí)出現(xiàn)峰值,此時(shí)宏臺(tái)階包含基本臺(tái)階的個(gè)數(shù)大約為48個(gè),臺(tái)階的斜率約為8.8×10-3。在高過飽和度σ=0.08和σ=0.09時(shí),晶體表面出現(xiàn)"凹坑"或者"孔洞",這些"孔洞"被臺(tái)階上的突起所包圍,我們認(rèn)為這些突起是由二維成核機(jī)制產(chǎn)生的,這也說明此時(shí)臺(tái)階的生長(zhǎng)是位錯(cuò)臺(tái)階的推移和二維成核生長(zhǎng)機(jī)制共同作用的結(jié)果。KDP晶體在不同飽和溫度的溶液中,臺(tái)階的推移速度都隨著過飽和度的增加呈現(xiàn)出相似的規(guī)律,晶體生長(zhǎng)過程中的過飽和度死區(qū)σd、線性過飽和度σ*、延長(zhǎng)線通過原點(diǎn)的臨界過飽和度σ'將v(σ)曲線大致分為三個(gè)區(qū)域,這三個(gè)過飽和度都隨著溫度的升高而減小。另外,在相同的過飽和度下,臺(tái)階推移速度隨著溫度的升高而增大。在不同飽和溫度下生長(zhǎng)的KDP晶體的激光損傷閾值都隨著過飽和度的增加呈現(xiàn)出先減低后升高的趨勢(shì),類似于"V"形變化。2.通過摻雜的方式,研究Fe~(3+)雜質(zhì)在不同的溫度、過飽和度下對(duì)KDP晶體生長(zhǎng)習(xí)性的影響。利用原子力顯微鏡技術(shù)和激光偏振干涉技術(shù)分別研究不同條件下KDP晶體(100)表面生長(zhǎng)臺(tái)階的微觀形貌和生長(zhǎng)速度。實(shí)驗(yàn)結(jié)果表明:利用傳統(tǒng)降溫法生長(zhǎng)的KDP晶體,隨著溶液中Fe~(3+)摻雜濃度的升高,臺(tái)階的聚并程度和斜率都增大,臺(tái)階分布的均勻性下降,生長(zhǎng)死區(qū)變大,生長(zhǎng)速度降低。當(dāng)Fe~(3+)濃度為30ppm時(shí),在不同飽和溫度的溶液中,KDP晶體的生長(zhǎng)速度隨著溫度的升高而增大。在高溫區(qū)域(~65℃C、75℃C),KDP晶體在摻雜溶液中的生長(zhǎng)速度要快于在未摻雜的溶液中。在飽和溫度約為55℃C,溶液中的Fe~(3+)濃度為5ppm時(shí),KDP晶體的臺(tái)階的聚并程度只有在低過飽和度(σ=0.02)時(shí)高于未摻雜的情況。此時(shí)臺(tái)階非常直,生長(zhǎng)均勻,并且在寬的臺(tái)階陣列上明顯分布著許多基本臺(tái)階。當(dāng)Fe~(3+)濃度為30ppm時(shí),臺(tái)階的聚并程度隨過飽和度的升高而增大,在相同的過飽和度下都大于未摻雜時(shí)的情況。當(dāng)Fe~(3+)濃度為50ppm時(shí),在低過飽和度下,臺(tái)階的聚并非常高;在高的過飽和度下,臺(tái)階扭折增多,變大。3.在溶液中加入100ppm、500ppm的有機(jī)添加劑CDTA,采用點(diǎn)籽晶快速法生長(zhǎng)了 KDP晶體。利用原子力顯微鏡技術(shù)從原子層面觀察不同濃度的CDTA對(duì)KDP晶體表面生長(zhǎng)臺(tái)階微觀形貌的影響,通過激光偏振干涉技術(shù)測(cè)量KDP晶體在摻雜不同濃度CDTA溶液中的臺(tái)階推移速度。實(shí)驗(yàn)結(jié)果表明:CDTA并沒有進(jìn)入KDP晶體內(nèi)部,CDTA對(duì)晶體生長(zhǎng)的作用主要發(fā)生在溶液中的生長(zhǎng)基元向晶體擴(kuò)散的過程中。有機(jī)添加劑CDTA對(duì)KDP晶體生長(zhǎng)習(xí)性的影響可以分為積極和消極兩個(gè)方面。當(dāng)溶液中添加適量濃度的CDTA時(shí),其能夠與溶液中的金屬雜質(zhì)離子結(jié)合形成配位鍵,降低它們的化學(xué)活性。生長(zhǎng)溶液中,雜質(zhì)的減少,使得晶體生長(zhǎng)的表面變得非常"干凈",雜質(zhì)對(duì)生長(zhǎng)臺(tái)階的釘扎效果降低,甚至消失。此時(shí)晶體表面生長(zhǎng)臺(tái)階的聚并程度急劇降低,主要以基本臺(tái)階為主,臺(tái)階的推移速度也得到大幅度的提高。當(dāng)溶液中加入過量的CDTA時(shí),其與溶液中的金屬雜質(zhì)離子形成螯合物之后,多余的CDTA會(huì)通過氫鍵的作用吸附在晶體的表面上,弱的氫鍵使得CDTA一直處于吸附與解吸附的過程中,當(dāng)其沉積在臺(tái)階陣列上時(shí),大的有機(jī)分子會(huì)形成"山包",這些"山包"不僅會(huì)吸附K+、H2pO4-等生長(zhǎng)基元,使其難以擴(kuò)散,而且也會(huì)阻礙生長(zhǎng)臺(tái)階在晶體表面的推移,此時(shí)臺(tái)階的聚并程度會(huì)有所增加,生長(zhǎng)速度也相應(yīng)的減慢。另外,當(dāng)加入過量的CDTA時(shí),KDP晶體沿X向和Z向的熱膨脹系數(shù)都降低。4.使用H_3PO_4、KOH調(diào)節(jié)溶液的pH值,分別采用傳統(tǒng)降溫法與點(diǎn)籽晶快速法在不同pH值的溶液中,生長(zhǎng)了 KDP晶體,利用原子力顯微鏡觀察晶體(100)面的微觀形貌和臺(tái)階結(jié)構(gòu),通過激光偏振干涉技術(shù)測(cè)量了 KDP晶體在不同pH溶液中的生長(zhǎng)速度,同時(shí)對(duì)生長(zhǎng)的KDP晶體進(jìn)行了激光損傷閾值的測(cè)試。實(shí)驗(yàn)結(jié)果表明:在低過飽和度(σ=0.01)下,KDP晶體表面生長(zhǎng)臺(tái)階的聚并程度隨著pH值的降低而減小,尤其是pH=3.5時(shí),生長(zhǎng)臺(tái)階以基本臺(tái)階為主。當(dāng)溶液的pH值偏離正常值(pH=4.2)時(shí),不論偏高還是偏低,所得到的KDP晶體的激光損傷閾值都有所升高。調(diào)高溶液的pH值到5.2時(shí),晶體表面生長(zhǎng)臺(tái)階上出現(xiàn)突起,這些突起隨著過飽和度的增加而變大。晶體的激光損傷閾值先增加后降低,在過飽和度σ=0.04時(shí),達(dá)到最大值,約為21J/cm2。調(diào)低溶液的pH值到3.5時(shí),隨著過飽和度的增加,晶體的生長(zhǎng)方式不僅存在螺旋位錯(cuò)臺(tái)階同時(shí)也存在二維成核生長(zhǎng)機(jī)制,生長(zhǎng)表面上的二維島不斷疊加和堆垛。晶體的激光損傷閾值在過飽和度σ=0.04和σ=0.06時(shí),分別達(dá)到最大值和最小值,約為27J/cm2和18.3J/cm2。將溶液的pH值調(diào)到pH=2.5時(shí),隨著過飽和度的增加,晶體表面生長(zhǎng)臺(tái)階的聚并程度和陣列寬度都呈現(xiàn)先增大后降低的趨勢(shì),臺(tái)階的斜率則是呈現(xiàn)先降低后增加的趨勢(shì)。晶體的激光損傷閾值總體呈現(xiàn)出降低的趨勢(shì),其中在過飽和度σ=0.08時(shí)出現(xiàn)一個(gè)小的波峰,約為22J/cm2。另外,不論調(diào)高還是調(diào)低溶液的pH值,KDP晶體(100)面的法向生長(zhǎng)速度都有所升高。
[Abstract]:With the development of Inertial Confinement Fusion (ICF) engineering, people have put forward higher requirements for the requirements, quality and growth speed of KDP crystals, which can be summed up as "fast, large size, high quality". "Fast": the number of KDP chips needed in the engineering, the growth cycle and the cost are reduced. "Large size". The requirements for crystal size in the ICF system can be met. "High quality": the ICF device can meet the requirements of the KDP crystal performance, such as high laser damage threshold, high transmittance and high optical uniformity. In recent years, the research on the KDP crystal is mainly in the growth process, optical quality, crystal structure and so on. In order to improve the growth speed and optical properties of KDP crystal fundamentally, the micromorphology and growth mechanism of crystal growth should be studied. As a classic aqueous solution growth crystal, temperature, supersaturation, impurity, pH and other medium environment have important influence on the growth habit and optical quality of the KDP crystal. Therefore, this paper is mainly selected. By changing the saturation temperature, supersaturation, pH value, and the doping of metal ions and organic additives, the influence of various medium factors on the micromorphology of the growth steps of KDP crystals and the growth rate are studied. The main contents of this paper are as follows: 1. the KDP crystals were grown at different saturation temperatures and different supersaturation. The laser damage threshold of the crystal was measured. The surface micromorphology of KDP crystals under different conditions was observed by atomic force microscopy. The laser polarization interference system was realized by laser polarization interference system. The relationship between the growth rate and the supersaturation of KDP crystals at different temperatures was measured. The experimental results showed that under low temperature (~35 C C), the growth steps of the crystal surface were in low supersaturation (sigma =0.01), intermediate supersaturation (sigma =0.05) and high supersaturation (sigma =0.08). The average number of the basic steps is 21,22,59 respectively. Correspondingly, the slope of the step also has the peak value under these three supersaturation, which is 9.26 x 10-3,9.64 x 10-3,8.47 x 10-3. respectively. When the high supersaturation is =0.08, the surface of the crystal appears "dendrite" steps. We think there may be a Ehrlich-Schwoebel on the step. E-S) potential barrier. In the medium temperature region (~45 C C, 55 C C), the step aggregation of the crystal surface is peak at the degree of sigma =0.04. At this time, the height of the steps at 45 C C is slightly higher than that of 55 C C. In the process of crystal growth, the slope of the steps appears at a peak in the middle supersaturation region, at 45 C C, the peak of the slope. When the value appears at Sigma =0.06, the corresponding supersaturation corresponding to the peak at 55 C is lower. At the time of sigma =0.04, the step width corresponding to the two peak positions is sharply reduced. At high supersaturation, the coalescence degree and step slope of the steps increase with the increase of supersaturation, which is more significant at 55 C C. At a high temperature region (~65 C) At the same time, the degree of convergence and the slope of the steps of the crystal surface all increase first and then decrease with the increase of supersaturation, all of which appear at the peak of supersaturation Sigma =0.03, at this time the number of the macro steps contains about 48 basic steps, and the slope of the steps is about 8.8 * 10-3. at high supersaturation Sigma =0.08 and sigma =0.09. The "holes" or "holes" appear on the surface of the body. These "holes" are surrounded by the protrusions on the steps. We think these protrusions are produced by the two-dimensional nucleation mechanism. This shows that the growth of the steps is the result of the lapse of the dislocation steps and the two dimensional nucleation mechanism. The.KDP crystal is in a solution of different saturated temperatures. The speed of the lapse is similar with the increase of supersaturation. The supersaturation dead zone in the crystal growth process is sigma D, linear supersaturation sigma, and the extension line is roughly divided into three regions through the critical supersaturation of the origin, V (sigma) curve, and the three supersaturation decreases with the increase of temperature. In addition, the same oversaturation is made. In addition, the step speed increases with the increase of temperature. The laser damage threshold of KDP crystals growing at different saturation temperatures decreases first and then increases with the increase of supersaturation, similar to "V" shape change.2., by doping, to study Fe~ (3+) impurities at different temperatures and supersaturation to KDP crystals. The influence of body growth habit. The micromorphology and growth rate of KDP crystal (100) surface growth step under different conditions were studied by atomic force microscope and laser polarization interference technique. The experimental results showed that the KDP crystal grown by the traditional cooling method, with the increase of Fe~ (3+) doping concentration in the solution, the degree of convergence of the steps and the degree of convergence. The slope ratio increases, the uniformity of the step distribution decreases, the growth dead zone becomes larger and the growth rate decreases. When the concentration of Fe~ (3+) is 30ppm, the growth rate of KDP crystal increases with the increase of temperature. In the high temperature region (~65 C, 75 C C), the growth rate of KDP crystal in the doped solution is faster than that in the undoped solution. In the solution, when the saturation temperature is about 55 C, and the concentration of Fe~ (3+) in the solution is 5ppm, the degree of convergence of the steps of the KDP crystal is higher than the unadulterated condition at low supersaturation (sigma =0.02). At this time, the steps are very straight, the growth is uniform, and many basic steps are shown on the wide step array. When the Fe~ (3+) concentration is 30ppm, The degree of convergence of the steps increases with the increase of supersaturation and is greater than that of the unadulterate at the same supersaturation. When the concentration of Fe~ (3+) is 50ppm, the step is very high at low supersaturation; at the high supersaturation, the step twisting increases, and the.3. is added to the solution, 100ppm, and the organic additive CDTA of 500ppm. The KDP crystal was grown by a point seed rapid method. The effect of CDTA on the surface growth of KDP crystal on the surface of KDP crystal was observed by atomic force microscopy. The step pushing velocity of KDP crystal in CDTA solution with different concentration was measured by laser polarization interference technique. The experimental results showed that CDTA did not advance. In the KDP crystal, the effect of CDTA on the growth of crystal mainly occurs during the diffusion of the growth base element in the solution. The effect of organic additive CDTA on the growth behavior of KDP crystal can be divided into two positive and negative aspects. When a proper concentration of CDTA is added to the solution, it can be combined with the metal impurity ions in the solution. The reduction of impurities in the growth solution makes the surface of the crystal grow very "clean", and the effect of the impurity on the growth step is reduced and even disappeared. At this time, the convergence of the growth steps of the crystal surface decreases sharply, the main step is the basic steps, and the speed of the step is also greatly improved. When an excess of CDTA is added to the solution, after the formation of a metal impurity ion in the solution, the excess CDTA is adsorbed on the surface of the crystal through the action of hydrogen bonds. The weak hydrogen bond makes the CDTA always in the process of adsorption and desorption. When it is deposited on the step array, the large organic molecules will form " The mountain bags "not only absorb the growth elements such as K+, H2pO4- and so on, make it difficult to spread, but also prevent the growth of the steps on the crystal surface. At this time, the degree of convergence of the steps increases and the growth rate slows down accordingly. In addition, when the excess CDTA is added, the thermal expansion coefficient of the KDP crystal along the X direction and the Z direction is reduced by.4.. The pH value of the solution was adjusted by H_3PO_4 and KOH. The KDP crystal was grown in the solution of different pH values by the traditional cooling method and the dot seed crystal fast method. The micromorphology and the step structure of the crystal (100) surface were observed by atomic force microscopy. The growth rate of KDP crystal in different pH solutions was measured by laser polarization interference technique, and the growth rate of KDP crystal in different pH solutions was measured. The laser damage threshold of the growing KDP crystal is tested. The experimental results show that the degree of convergence of the growth steps of the KDP crystal decreases with the decrease of the pH value at low supersaturation (sigma), especially when the pH value is reduced, especially at pH=3.5, the main steps are the basic steps. When the pH value of the solution deviates from the normal value (pH=4.2), it is high or low. The laser damage threshold of the obtained KDP crystal increases. When the pH value of the high level solution reaches 5.2, the surface growth steps appear on the surface of the crystal. These protrusions become larger with the increase of supersaturation. The laser damage threshold of the crystal increases first and then decreases, and the maximum value is reached when the supersaturation is Sigma =0.04, which is about the pH value of the solution of 21J/cm2.. At 3.5, with the increase of supersaturation, the growth mode of the crystal not only has the spiral dislocation steps but also the two dimensional nucleation growth mechanism, and the two dimensional islands on the growth surface are stacked and stacked continuously. The laser damage threshold of the crystal reaches the maximum and the minimum value at supersaturation Sigma =0.04 and sigma =0.06 respectively, which is about 27J/cm2 and 18.3J/cm. 2. when the pH value of the solution is transferred to pH=2.5, with the increase of supersaturation, the convergence degree and the array width of the crystal surface growth step increase first and then decrease, and the slope of the steps decreases first and then increases. The laser damage threshold of the crystal presents a tendency to decrease in general, in which the supersaturation is Sigma =0.08. A small peak, about 22J/cm2, appeared. In addition, the normal growth rate of KDP crystal (100) plane increased with increasing or decreasing the pH value of the solution.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：O78

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相關(guān)期刊論文 前10條

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本文編號(hào)：2161736