室温辐射探测器用碲锌镉晶体的退火改性研究进展

碲锌镉(CdZnTe)作为一种重要的Ⅱ-Ⅵ族化合物半导体,因其具备优异的光电性能,成为制备室温辐射探测器的理想材料。但生长态的CdZnTe晶体中不可避免地会引入Cd空位、沉淀/夹杂相、杂质和位错等缺陷,严重影响了所制备器件的质量和光电性能。因此,需对生长态晶体进行退火改性处理以提高晶体的质量。本文分析了CdZnTe材料中存在的主要缺陷,重点综述了退火改性工艺如退火温度、退火时间、退火气氛以及退火方式对CdZnTe晶体质量及探测器性能的影响。     

高温退火对PVT法生长的AlN晶体质量的影响（英文）

在PVT法生长AlN晶体的过程中,很难保持理想的热力学平衡状态,不可避免地会产生晶体缺陷。高温退火技术对提高晶体完整性十分有效，受到了广泛关注。本工作在N₂气氛环境下对PVT法生长的AlN晶片进行高温退火研究。为了评价退火前后AlN晶体的质量和结构变化情况,进行了高分辨率X射线衍射(HRXRD)和拉曼光谱分析。通过室温光致发光(PL)和吸收光谱对AlN晶体的光学性质以及与杂质相关的带隙变化情况进行了表征。在1400～1800℃退火后, AlN晶体质量显著提高。1400℃退火后,(10-12)晶面的X射线摇摆曲线的半峰宽(FWHM)从104.04 arcsec减小到79.92 arcsec。随着退火温度升高,吸收性能明显增强,带隙增大,说明高温退火处理有利于提高AlN晶体的质量。二次离子质谱(SIMS)结果表明,退火过程降低了C杂质,增加了AlN晶体的带隙,这与光吸收结果一致。     

热退火对KDP晶体微结构的影响

用X射线衍射和Raman光谱技术研究了KDP晶体165℃退火前后微观结构的变化。实验发现退火24h可以减小晶体生长过程中带来的晶格的畸变，提高了晶体的完整性，缩小晶体中键长和键角的变化范围，使晶体内应力得以部分释放。对于快速生长的晶体，退火的效果更加显著。     

提拉法Tm:YAG晶体的生长缺陷研究

采用提拉法(CZ)生长了质量优异的Tm:YAG晶体.部分晶片在1000℃的空气气氛中退火25h.借助光学显微镜、扫描电子显微镜(SEM),结合化学腐蚀法,对Tm:YAG晶体退火前后(111)面的缺陷特征进行了研究. Tm:YAG晶体(111)面的位错腐蚀坑呈三角形. 在偏光显微镜下观察了退火前后Tm:YAG晶体(111)面的应力双折射.同时应用高分辨X射线衍射法测定了晶体的完整性.实验结果表明,长时间空气气氛下高温退火有效降低了晶体中总的位错密度,提高了晶体质量.     

Hg1-xMnxTe晶体的生长及电学性能

利用ＡＣＲＴ－ＶＢＭ法生长Ｈｇ１－ｘＭｎｘＴｅ晶体，并对所得晶体作出宏观和微观质量评价，为改善晶体的电学性质，将生长态的晶体在低温下长时间退火。实现了晶片的反型，Ｈａｌｌ电测量的结果表明位错的数量、分布及富Ｔｅ相、晶界、杂质等的存在都对晶体的电学性质有显著的影响。     

退火工艺对SiO2-Al2 O3-MgO-F系玻璃陶瓷分相和析晶的影响

以SiO2、Al2O3、MgO和AlF3为主要原料,采用高温熔融法,在一定温度下将原料熔化,然后将熔体浇铸到预热的模具中,经不同退火工艺得到基础玻璃。将此玻璃快速加热到析晶温度,进行相同的析晶处理,得到玻璃陶瓷样品。应用TEM、SEM和XRD等技术,系统研究了退火工艺对SiO2-Al2O3-MgO-F系玻璃陶瓷分相和析晶的影响。结果表明：随着退火温度的提高,玻璃的结构逐渐得到松弛,促进了Mg^2 和F^-离子的扩散,玻璃内分相程度逐渐增大,其分相形貌由液滴状→连通状→团簇状过渡;玻璃的分相程度对高温析晶时晶体的析出形态也有一定影响,与低温退火的玻璃相比较,高温退火时析出的云母晶体更加均匀;随着退火时间的延长,析出的晶体变得越来越细小,晶体间的交错度和晶体的均匀程度逐渐增大。     

退火对提拉法生长Lu2Si2O7:Ce晶体闪烁性能的影响

Lu2Si2O7:Ce (LPS:Ce)表现出较高的光输出,平均值约26000photons/MeV (简写为ph/MeV),但通过提拉法获得的晶体发光效率很低. 实验对LPS:Ce晶体进行了不同气氛下的退火,研究退火条件对LPS:Ce的发光效率等闪烁性能的影响. 发现在Ar气氛下退火对LPS:Ce发光效率的提高没有作用,在空气气氛下退火后可显著提高LPS:Ce的发光效率. 通过不同退火工艺的比较,确定了提高LPS:Ce发光效率的最佳退火制度:空气气氛下,退火温度1400℃,退火时间根据样品的大小决定,样品越大,需要的退火时间越长. 同时讨论了退火过程中,LPS:Ce吸收谱和UV-ray激发发射谱的变化趋势.     

碲锌镉单晶片的退火方法

探索了一种Cd1-xZnxTe(CZT)探测器晶片退火的新装置和新方法,该装置可以方便有效的对CZT单晶片进行同组分源退火研究.利用XRD、红外透射谱和晶体电阻率表征了采用该装置在富Cd的同组分CZT粉末源包裹下,选择适宜的退火温度和时间进行退火后的CZT单晶片,晶片的电阻率有一定的提高,红外透过率有一定改善.XRD分析表明,经过退火后,CZT单晶片中的cd组分含量有一定增加.采用该方法退火后,晶体品质有一定提高.     

Y3+:PbWO4晶体低剂量辐照行为研究

三价稀土离子(Ｌａ^３＋、Ｌｕ^３＋和Ｙ^３＋等)掺杂显著地提高了钨酸铅晶体的辐照硬度,但是部分Ｙ^３＋掺杂钨酸铅晶体表现出特殊的低剂量辐照行为,即光产额辐照后升高,并且辐照硬度对退火温度较敏感 本研究挑选了存在这一现象的Ｙ^３＋:ＰｂＷＯ_４晶体,测试不同温度的退火处理对晶体透过率、光产额和辐照硬度的关系,发现:辐照后光产额升高的现象同时存在于晶体的晶种端,而不是只集中在晶体顶端,并且和辐照前后晶体在４００~５００ｕｍ波段附近的透过率变化有关;生长态Ｙ^３＋:ＰＷＯ晶体中导致４３０ｕｍ吸收带的色心的稳定性很低,低剂量辐照对该色心有“漂白”作用,辐照剂量率加大则晶体表现出光产额的降低;分段晶体的系列退火实验解释了辐照硬度对退火温度较为敏感这一现象,为进一步深入研究提供了实验基础．     

Y3+:PbWO4晶体低剂量辐照行为研究

三价稀土离子（La^3 ,Lu^3 ,和Y^3 等）掺杂显著地提高了钨酸铅晶体的辐照硬度,但是部分Y^3 掺杂钨酸铅晶体表现出特殊的低剂量辐照行为,即光产额辐照后升高,并且辐照硬度对退火温度较敏感,研究研究挑选了存在这一现象的Y^3 :PbWO4晶体,测试冰同温度的退火处理对晶体透过率,光产额和辐照硬度的关系,发现,辐照后光产额升高的现象同时存在于晶体的晶种端,而不是只集中在晶体顶端,并且和辐照前后晶体在400－500nm波段附近的透过率变化有关;生长态Y^3 :PbWO4晶体中导致430nm吸收带的色心的稳定性很低,低剂量辐照对该色心有“漂白”作用,辐照剂量率加大则晶体表现出光产额的降低,分段晶体的系列退火实验解释了辐照硬度对退火温度较为敏感这一现象,为进一步深入研究提供了实验基础。     

Growth and characterization of gel grown pure and mixed iron-manganese levo-tartrate crystals

Several applications of iron tartrate and manganese tartrate compounds are reported in the literature. In the present investigation, we have grown pure and mixed iron (II)-manganese levo-tartrate crystals by single diffusion gel growth technique. Crystals with spherulitic morphology were harvested. The colouration of the crystals changed from black to pinkish brown upon increasing the content of manganese in the crystals. The crystals were characterized by FTIR spectroscopy, powder XRD, TGA, VSM and dielectric study. Crystal structures of different mixed crystals were studied. From TGA it was observed that on heating the hydrated crystals became anhydrous and then converted into oxides. Paramagnetic nature of the crystals was revealed from VSM study. The variation of the dielectric constant with frequency was studied. The results are discussed.     

Growth and study of some gel grown group II single crystals of iodate

Single crystals of calcium iodate and barium iodate were grown by simple gel technique by single diffusion method. The optimum conditions were established by varying various parameters such as pH of gel solution, gel concentration, gel setting time, concentration of the reactants etc. Crystals having different morphologies and habits were obtained. Prismatic, dendritic crystals of barium iodate and prismatic, needle shaped, hopper crystals of calcium iodate were obtained. Some of them were transparent, some transluscent, and few others were opaque. Both the crystals were studied using XRD, FT-IR, and thermal analysis. The crystals were doped by iron impurity. The effect of doping was studied using IR spectroscopy and thermal analysis.     

四丁基溴化铵水合物结晶过程的可视化研究

对静止状态下四丁基溴化铵水溶液在铜板表面上的降温结晶过程进行了研究。结合降温过程的温度测量和可视化研究,得出了水和不同质量分数四丁基溴化铵水合物结晶温度曲线,分析了曲线的异同,并对结晶过程的图像进行了分析讨论。研究表明:铜板表面结晶生成的位置具有随机性;质量分数为10%的TBAB溶液中A型晶体较B型晶体更容易生成,质量分数分别为20%和30%的TBAB溶液中A型晶体与B型晶体同时生成。结晶生长速度与铜板表面纹理方向有关。     

ZnO single crystals: Synthesis and characterization

Zinc oxide crystals grown in a single basic mineralizer in hydrothermal autoclaves are of poor quality. The crystals are transparent, pale green or pale yellow in color depending on different technical growth conditions. The quality of crystals under different conditions was observed by X-ray rocking curves measurement. The use of ultra-pure nutrient improves their perfection and purity. Zinc oxide bulks that were grown by the hydrothermal method in a mixture of KOH and LiOH aqueous solutions are of good quality.     

高掺锌富锂铌酸锂体抗光损伤能力的研究

以Czochralski法生长Zn(6mol%)：LiNbO3,Li/Nb=0.94,0.97,1,1.02。测试晶体的光损伤阈值。采用质子交换法制作高掺锌富锂铌酸锂晶体光波导,研究了它们的抗光损伤能力。     

Synthesis of black cBN single crystal in hBN-Li3N-B system

Generally, cBN crystals exhibit many colors from white, yellow to black due to different impurities and defects present in them. In this paper, black cBN crystals with relatively integrated octahedral morphology were obtained in hBN-Li₃N-B system under high temperature and high pressure. The color, morphology and property of the synthesized cBN crystals were extensively studied. X-ray diffraction (XRD) and Raman spectroscopy were used to characterize the synthesized cBN single crystals. We found that boron entered into the synthesized black cBN crystals through the way of substituting N vacancy and resulted in a change in color and morphology. We brought out a different coloration mechanism compared with a previous study according to the results in this system. The residual stress in the synthesized cBN crystals, which was calculated by the results of Raman spectroscopy, decreased markedly with the increase in the content of additive boron.     

氢对钛晶体弹性模量影响的第一原理研究

为了研究氢对钛晶体弹性模量的影响,采用基于密度泛函理论的第一原理赝势平面波方法对α-Ti、β-Ti、不同钛-氢原子比的α-Ti-H和β-Ti-H晶体模型进行了完全几何优化,计算了优化后晶体的弹性模量,通过差分电荷密度分析了氢影响钛晶体弹性模量的作用机理.计算得到的Ti/H原子比为16∶1的α-Ti-H晶体的弹性模量小于α-Ti晶体,而Ti/H原子比为8∶1的α-Ti-H晶体的弹性模量大于α-Ti晶体.不同Ti/H原子比的β-Ti-H晶体的弹性模量均大于β-Ti晶体.研究表明,氢降低了低氢含量的α-Ti-H晶体的弹性模量,提高了β-Ti-H晶体的弹性模量.     

Influence of NH4Cl on the < 1 0 0> directed growth and properties of ADP crystal

Good quality, pure and ammonium chloride added < 1 0 0> directed ADP single crystals with different sizes were grown by Sankaranarayanan-Ramasamy method with the vision to improve the properties of the crystal. The grown crystals have cylindrical morphology and the crystals were subjected to UV-Vis., DTA, microhardness, laser damage threshold, dielectric, piezoelectric and SHG studies. The addition of ammonium chloride improves the quality and yields crystals with transparency more than 80% in minimum duration of growth. Higher laser damage threshold and mechanical stability were observed in ammonium chloride added ADP crystals. Low dielectric loss shows that the grown crystal contains minimum defects. Good piezoelectric behaviour was observed for the grown crystals. The SHG efficiency of the crystals was obtained using Nd-YAG laser, which is approximately 3 times that of pure ADP and shows the suitability of the ingot for nonlinear optical applications.     

Fabrication of heterostructures of halogen-bridged quasi-one-dimensional mixed-valence transition metal complexes

Single-heterostructure crystals of a series of halogen-bridged quasi-one- dimensional mixed-valence transition metal complexes (HMMCs) were fabricated by selective coordination epitaxial growth (SCE growth). The overgrowth crystals of the HMMC were grown on the columnar crystals of the substrate HMMC in solution. The single-heterostructure crystals were epitaxially grown only when the two HMMCs had similar crystal structures. If their crystal structures were different, no heterostructure crystal was grown. This result suggests that the degree of mismatch between the crystal structures of the substrate and the overgrowth is the predominant factor which determines the SCE growth of the HMMCs.     

Crystal growth and characterization of Deuterated Glycine Phosphite single crystals

Deuterated Glycine Phosphite single crystals were grown by low temperature solution growth method using high purity deuterated water as solvent. Deuteration content of the as grown crystals was improved by repeated recrystallisation process. Structural perfection, transparency and the functional groups present in the grown crystals were identified using different characterization analyses. Dielectric behaviors of the as grown specimens were examined through thermal and impedance analysis. Partial deuteration of the grown crystal was confirmed from the DSC and dielectric results.