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题名	白宝石（Al_2O_3）光学晶体和α-BaB_2O_4双折射光学晶体的缺陷和生长研究
作者	周国清
学位类别	博士
答辩日期	2000
授予单位	中国科学院上海光学精密机械研究所
导师	干福熹
关键词	Al_2O_3晶体 温梯法 α－BaB_2O_4晶体 晶体生长 晶体缺陷 α－BaB_2O_4规戒律crystal
中文摘要	温度梯度法（TGT）生长大尺寸白宝石Al_2O_3晶体和提拉法生长α－BaB_2O_4晶体都是新发展的研究工作。大尺寸Al_2O_3晶体的制备为研究下一代蓝光LED的衬底材料和优质光学器伯提供了物质保证。本论文包括Al_2O_3晶体和α－BaB_2O_4晶体的生长、缺陷、光学性能研究工作，主要结论概括为以下几点：根据温梯法的生长特点和原料、晶体中杂质离子分析结果，最先提出了该方法生长的大尺寸Al_2O_3晶体带颜色及去色脱碳的退火机理；创造性地探索出一套适合于电阻法生长的Al_2O_3晶体去色脱碳的退火装置、方法；采用先氧化气氛后还原气氛退火的办法使原来带有颜色的Al_2O_3晶体变得无色透明，提高了晶体的完整性；首次采用同步辐射X线光衍射、X射线双晶衍射开貌术等实验手段全面分析了大晶体内部的位错分布及走向，晶体内部的位错密度一般为10~3-10~4cm~(-2)量级，靠近坩埚部位的位错密度高达10~5cm~(-2)；双晶衍射形貌术表明Al_2O_3晶体的大部分区域内完整性很高，部分样品接近于理想完整晶体的摆曲线的半峰宽，仅为10秒弧。通过合理地控制晶体生长程序和选择优质籽晶，TGT法可以生长出高质量的Al_2O_3晶体，但在日体生长过程控制不好的情况下，晶体中存在镶嵌等缺陷结构；Al_2O_3晶体的紫外辐照实验表明该晶体具有很强的抗紫外辐照性能；大 剂量γ射线辐照表时：温梯法生长的Al_2O_3晶体存在位于203nm和227-256nm处的吸收带，分别对应于其本征F心和F~+心的吸收。经先氧化后还原气氛退火后，F心和F~+心的色心浓度明显减少，此外，在ESR谱出现Fe~(3+)，F_2~+和Cr~(3+)等的共振吸收谱。在国际上次首次采用提拉法生长出φ50*40mm~3的α－BaB_2O_4晶体，生长方向为[0001]，晶体完整、无色透明；提出了三种固相反应的原料制备方法，并保证B＿2O＿3过量1mol%；采用独特的生长装置和程序有效地解决了α－BaB_2O_4晶体易开裂的问题；首先采用化学腐蚀法、白光X射线衍射术、射线双晶衍射形貌术等研究了α－BaB_2O_4晶体的位错密度；首次采用同步辐射X射线劳埃定向术研究了α－BaB_2O_4晶体的结晶形态及生长习性；结果发现αBaB_2O_4晶体的缺陷以位错为主，部分α－BaB_2O_4晶体中存在生长条纹。最先采用自准直技术测试了α－BaB_2O_4晶体的两个折射率 n_0和n_e，双折射率Δn = 0.116,推导了其折射率色散方程，设计了Wollaston分光棱镜；采用XeCl准分子激光器(308nm)对α－BaB_2O_4晶体进行了辐照实验，发现晶体在紫外光谱区没有任何吸收，但在红外区不同程度地存在光吸收。
英文摘要	It is completely advanced research work of sapphire crystal with four inches in diameter grown by temperature gradient technique (TGT) and alpha meta borate barium α－BaB_2O_4 crystal grown by Czochralski method. The development of large-sized sapphire ensures the GaN substrate of next generation of LED and optical medium materials. The α－BaB_2O_4 crystal as a novel birefringent crystal is crucial to the progress of light communication in UV region. Several conclusions have been drawn from this thesis as following. The sapphire crystals with φ118 * 80mm~3 in [0001] orientation have been solely grown by temperature gradient technique (TGT) at home and abroad. The sapphires are integrated and transparent, but with a bit of color. The decolorization and decarbonization annealing mechanisms have been forwarded on the basis of combination of crystal growth feature and GDMS results of impurities. One kind of annealing facility and annealing conditions have been found out for sapphire boules grown in resistance-furnace as well as TGT method. The little-colored sapphires turn out completely colorless after being annealed in oxidization and reduction atmosphere successively. The perfectness of sapphire crystals have been greatly improved. The defects in TGT-sapphire are mainly edge-typed dislocation, mosaic and color centers through the chemical etching method, X-ray white-beam diffraction of synchrotron radiation and double-crystal diffraction topography. The typical dislocation density of sapphire is merely 10~3-10~4cm~(-2), but the high dislocation density of 10~5cm~(-2) sometimes occurs at near the wall of Mo crucible. The sapphire crystals with high optical quality can be grown by TGT if the whole growth process are controlled properly. The perfectness of TGT-sapphire is so high that the FWHM of double-crystal diffraction rocking curve is just 10 arcsecond. The sapphire crystals have a strong irradiated-resistance in UV band after exposing it in 308n wavelength for 180 minutes. The transmission curves of sapphire have an absorption peak of 203 nm and absorption band of 227-256nm, which are respectively caused by absorption of F and F~+ color centers, after being irradiated in different doses of γ-ray from ~(60)Co source. Moreover, the resonance absorption of Fe~(3+), Cr~(3+) and F_2~+ is also occurring at ESR spectrum. The α－BaB_2O_4 crystals with 50mm in diameter and 40mm in height have been firstly grown by Czochralski method at home and abroad. The α－BaB_2O_4 crystal is colorless, transparent and without cracking. The cracking problem has been overcome by a special growth procedure. The dislocation density, crystallization morphology and growth habit of α－BaB_2O_4 crystal have been systematically studied by chemical etching method, X-ray laue orientation of synchrotron radiation, double-crystal diffraction topography. The growth striation and irregular dislocation consist of the primary defect in α－BaB_2O_4 crystal. The convex solid-liquid interface is stable during the whole growth process. The two refractive indices of n_0 and n_e is respectively 1.655, 1.539, i.e. Δn = 0.116 and the Sellmier Equation is also deduced. One set of Wollaston prism has been designed according to the refractive indices. The α－BaB_2O_4 crystal has no absorption peak in UV band but a bit of absorption in IR region after irradiation in 308nm wavelength.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/15370]
专题	上海光学精密机械研究所_学位论文
推荐引用方式 GB/T 7714	周国清. 白宝石（Al_2O_3）光学晶体和α-BaB_2O_4双折射光学晶体的缺陷和生长研究[D]. 中国科学院上海光学精密机械研究所. 2000.

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