天然金刚石晶体缺陷的同步辐射形貌研究

本文利用北京同步辐射白光形貌术研究了辽宁天然金刚石晶体的缺陷问题，实验结果表明，金刚石晶体中存在有位错，生长带和生长带和孪晶等缺陷，文中对位错进行了详细讨论，并确定其特征量。     

Nd∶GGG激光晶体的同步辐射X射线白光形貌研究

应用同步辐射X射线白光形貌术,对Nd∶GGG晶体中的缺陷进行了研究,观察到晶体中的主要缺陷是生长条纹和位错,对生长条纹产生的机理和位错的类型进行了分析讨论,生长条纹是由于温度波动引起生长率的起伏产生的,确定晶体中的位错有刃型位错、螺旋位错和混合位错。根据生长条纹和位错的生成机制,提出了一些改进生长工艺的措施和方法,为生长质量更高的晶体提供了参考。     

Nd:GGG激光晶体的同步辐射X射线白光形貌研究

应用同步辐射X射线白光形貌术,对Nd:GGG晶体中的缺陷进行了研究,观察到晶体中的主要缺陷是生长条纹和位错,对生长条纹产生的机理和位错的类型进行了分析讨论,生长条纹是由于温度波动引起生长率的起伏产生的,确定晶体中的位错有刃型位错、螺旋位错和混合位错.根据生长条纹和位错的生成机制,提出了一些改进生长工艺的措施和方法,为生长质量更高的晶体提供了参考.     

合成金刚石晶体缺陷的同步辐射形貌研究

采用同步辐射白光貌相术研究合成金刚石单晶体中的晶体缺陷,观察到晶体中存在籽晶,籽晶周围存在着大量的位错线.位错线起源于籽晶表面,终止于晶体表面.计算了位错束的空间走向和位错密度.分析了晶体的生长阶段和影响晶体缺陷的主要因素,指出通过减少籽晶表面的缺陷,保持生长条件的稳定,能够有效地降低合成金刚石晶体中缺陷的密度,提高合成金刚石晶体的完整性.     

用光弹性模型显示刃型位错的应力场

位错是晶体材料中实际存在的一种结构缺陷。位错理论可以解释晶体材料的生长、相变、扩散、范性形变、加工硬化、回复、再结晶等重要现象,以及其它许多物理、化学性质。研究位错与位错、位错与其它晶体结构缺陷之间的交互作用,能说明晶体材料的许多性质。其交互作用起因于它们应力场的交互作用。因此,研究位错应力场也是位错理论中一个重要的问题。熟悉位错的基本原理,不仅对于从事材料科学与工程的广大科技人员是必要的,而且对于从事实际工作的技术人员和工程师也都是必要的。位错的应力场,一般应用弹性力学研究弹性体中相当于位错的畸变的方法,简化成为连续性介     

KTiOAsO4晶体的生长缺陷研究

研究ＫＴｉＯＡｓＯ₄晶体的生长缺陷,对于改善它的性能和应用前景,有很大的意义．本文利用化学腐蚀光学显微术和同步辐射Ｘ射线形貌术研究了ＫＴｉＯＡｓＯ_４晶体的缺陷,实验结果表明,两种腐蚀剂对于显示ＫＴＡ晶体的表面缺陷效果显著,ＫＴＡ晶体中主要的缺陷有铁电畴、生长层、扇形界、位错和包裹物．讨论了这些缺陷形成的原因。     

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...     

天然金刚石包体的同步辐射研究

利用北京同步辐射白光形貌术和同步辐射荧光分析对天然金刚石包体进行了研究,结果发现,晶体中存在有很多极细小的包体及大量位错,文中对包体进行分析,并确定出因其产生的位错的特征量。     

BiB3O6晶体的褐色缺陷

利用同步辐射白光形貌术和透射电子显微镜,对BiB3O6晶体的缺陷进行研究.靠近籽晶部位,可以观察到包藏、位错和生长扇面边界,而远离籽晶的位置,没有发现任何微观的缺陷.通过实验观察,孪晶和生长扇面边界可能是导致晶体中褐色区域的形成原因.提出了消除缺陷的方法.     

193 nm激光下不同含量Y杂质CaF2晶体辐照损伤研究(英文)

氟化钙晶体的抗辐照性能是其在深紫外光刻应用中的关键性能之一,目前氟化钙晶体在193nm激光辐照下的损伤过程尚不清楚。本文报道了193 nm激光辐照下氟化钙晶体的损伤行为及影响损伤的关键缺陷因素。通过193nm激光辐照试验,发现晶体损伤主要表现为晶体内部产生的辐照诱导色心与表面产生的辐照诱导损伤坑。通过紫外–可见分光光度计对辐照诱导色心分析,并将不同色心吸收系数与Y杂质含量进行线性拟合。结果表明:Y离子具有与F心结构波函数发生重叠的低位轨道,两者发生轨道杂化易形成色心稳定结构;线性拟合结果表明Y离子含量与氟化钙晶体本征色心之间存在线性关系,说明Y元素是影响色心形成的关键杂质离子。实验表征了辐照诱导损伤坑的元素分布和结构缺陷。EDS结果表明损伤坑处伴随着钙元素含量上升和氟元素含量下降,证实H心扩散、F心聚集导致了辐照损伤;EBSD结果表明表面辐照损伤优先在位错处产生。因此,降低杂质含量及位错密度是提高氟化钙晶体在193 nm激光下抗辐照损伤性能的重要途径。     

Investigation on defects in HPHT-grown diamond single crystals

In the diamond single crystals synthesized at high temperature and high pressure using FeNi as catalyst, there are usually supersaturated vacancies and inclusions formed during the diamond crystal growth and rapid cooling from high temperature. Some defects such as prismatic dislocation loops, stacking faults and array of dislocations are closely related to such supersaturated vacancies and inclusions. The supersaturated vacancies agglomerate into discs on the (111) close-packed planes, subsequent collapse of the discs forms the dislocation loops and stacking faults. The thermal internal stresses, which are caused by the difference of thermal contraction between the diamond and the inclusions due to the difference of thermal coefficients between them as the diamond is cooled from high temperature, may be relieved by the formation of array of dislocations. In the present paper, these defects in the diamond single crystals were directly examined by transmission electron microscopy (TEM). The characteristics and formation process of these defects were analyzed briefly.     

Interaction of Fine Fe Particles with Structural Defects on {111} Faces of Synthetic Diamond Crystals in a Hydrogen Atmosphere

Data are presented on the interaction of fine Fe particles with structural defects on the octahedral faces of synthetic diamond crystals during catalyzed diamond gasification in a hydrogen atmosphere at 900°C. The defects were revealed by etching in molten NaNO₃. The results indicate that the penetration of metal particles into the crystal bulk is only possible at the outcrops of screw dislocations. The density of such defects determines whether lateral (parallel to the face) or normal (perpendicular to the face) etching prevails.     

大尺寸掺硼宝石级金刚石单晶的高温高压合成及电学性质研究

在5.4GPa、1200～1400℃条件下,进行掺硼金刚石单晶的合成研究。成功合成出了重0.2g,径向尺寸达6.0mm的优质掺硼金刚石单晶。考察了合成体系中硼添加量对晶体透光度的影响。利用伏安特性和霍尔测试,得到了掺硼金刚石单晶常温电阻率、霍尔系数及霍尔迁移率和合成体系中硼添加量的关系。研究发现,随着合成体系中硼添加量的增加,晶体的电阻率和霍尔迁移率都呈下降趋势;霍尔系数随硼添加量的增加先下降后上升。随着硼添加量的增加:晶体常温电阻率下降,表明硼杂质已进入到金刚石晶体中。霍尔迁移率的下降,可能是晶体缺陷增多对载流子散射所致。霍尔系数先减小后增大,这可能与进入金刚石的硼元素量增大及晶体缺陷增多有关。     

Study of crystal defects using ion channelling and channelling radiation

The channelling technique to study crystal defects is described and its applications to various kind of defects to study their atomistic nature have been reviewed. Special emphasis has been placed on the applications to extended defects like dislocations. Finally a related new technique being developed for the last few years, namely the channelling radiation technique has been discussed along with its applications to study the dislocations.     

X-ray topography study on imperfections in synthetic mica (fluorophlogopite) crystal

The X-ray diffraction topography study of imperfections in synthetic mica (fluorophlogopite) crystal is reported. The main defects in synthetic fluorophlogopite crystal are one-dimensional disorder, sub-grain boundaries and dislocations. The orientations of the sub-grain boundaries and dislocations are normal to the growth front. Many defects in synthetic micas originate from the seed crystal. By controlling the orientation of the seed crystal, large-sized fluorophlogopite crystals with almost no central defects have been synthesized. In view of its excellent chemical and electrical properties, flat surface and strong X-ray diffraction intensity, large-sized fluorophlogopite crystal will find many important applications in various fields.     

Dislocation Mechanism of Diamond Crystal Growth from Fe—Ni—C System at High Temperature—High Pressure

Some dislocations,which are generated in the diamond single crystal during the diamond crystal growth from Fe-Ni-C system,may affect diamond crystal growth mode at high temperature-high pressure(HPHT). The concentric dislocation loops were successfully examined by Moire images.The surface morphologies of growing and as-grown diamond single crystals were observed by scanning electron microscopy(SEM).The concentric dislocation loops formation process and their effect on the diamond crystal growth mode were analyzed.It should be noted that whatever the nature of the dislocation is ,should the Burgers vector of dislocation has a component at the direction normal to the growth interface,the dislocation will make the face parallel to the growth interface grow into spiral face.The presence of consecutive spiral steps on the diamond crystal surface also provides a direct evidence of the dislocation mechanism of diamond crystal growth.     

The effect of annealing on residual stress and dislocation propagation in silicon slices with damaged layer induced by scribing

The effect of annealing on residual stress and dislocation propagation in silicon slices with a damaged layer induced by diamond scribing, laser scribing and diamond blade cutting was studied by infra-red photoelastic measurements and dislocation pit observations. Residual stress and dislocation propagation both showed clear annealing temperature dependence at temperatures above 500° C, although the residual stress was greatly reduced by a small degree of dislocation propagation. The experimental results can be explained using the stress recovery theory by the model of the damaged layer with a mosaic crystal layer and a single crystal layer with micro-cracks and dislocations.     

4H-SiC高速同质外延研究

研究了生长温度为1400℃时4H-SiC同质外延膜的生长速率、表面形貌及缺陷. 拉曼表征并结合KOH腐蚀表明外延膜中未出现3C-SiC多晶, 为单一的4H-SiC晶型. 通过KOH腐蚀发现, 低生长速率和高C/Si比有利于衬底表面的基平面位错(BPDs)转变成露头刃位错(TEDs). 在高生长速率下, 外延膜的表面三角形缺陷和位错密度会显著增加. 通过引入界面层, 可以实现生长初期的平滑过渡, 极大地降低高生长速率下外延膜的缺陷密度.     

Study of individual grown-in and indentation-induced dislocations in GaN by defect-selective etching and transmission electron microscopy

Vickers diamond indentation at 370°C has been employed to introduce dislocations into the plate-like (000-1) N-polar GaN single crystals. It has been established that using standard Vickers diamond indenter, well-defined ‘rosettes’ of defects are formed under 1.5–2 N load applied for 10 min. The resolved patterns of dislocation-related etch pits are formed using molten KOH–NaOH eutectic (E) at 200°C for 1.5–2 min. Individual grown-in dislocations are revealed by this E etch in the GaN matrix. Transmission Electron Microscopy confirmed the correlation of etch pits to individual dislocations emerging at the surface. Nano-crystalline material was found in the highly deformed central region of the indentation rosette. The structure of these nano-crystals was analyzed using electron diffraction. Speculative explanation on a phase transition induced by high local pressure is briefly discussed.     

Defect-and-impurity state of type Ib diamond single crystals of cubic habit

Type Ib diamond single crystals of size to 5–6 mm and to 2.4 carats in weight have been grown at high pressures and temperatures. The defect-and-impurity state and dislocation structures of these crystals have been studied using the IR and optical microscopies as well as the method of the selective etching. To produce type Ib crystals of cubic habit has been made possible by the minimization of the growing temperature. Defect regions in the form of a cone with the basis 0.2–1.8 mm in diameter and 0.5–2.5 mm in height are contained by these crystals. The study of the cone-shaped defect regions using the selective etching showed that at the exposure on the faces the etching pits are of the tetragonal shape and the dislocation density in them exceeds the density of dislocations in crystals that were grown under the usual conditions by 70 to 100 times. The observed defect regions are formed in the course of the diamond crystals growth as the temperature decreases by ~ 30–35°C at the crystallization front because of the increasing heat sink in the direction of a seed crystal.