15;Yb:YAlO3晶体的生长和光谱研究

本文采用中频感应提拉法成功生长了Yb掺杂浓度高达15;的YAlO3晶体,晶体尺寸约30mm×120mm,晶体质量较好.对生长的晶体沿垂直于b轴方向进行了切割,将样品分别在氢气和氧气中退火后进行了吸收和荧光测试.在氧气中退火后的样品具有较大的峰值吸收宽度,但同时也增加了基线的吸收系数.分析表明在940nm泵浦下,1011nm和1037nm将是实现激光输出的候选波长.     

紊流模型模拟分析旋转对提拉大直径单晶硅的影响

本文采用紊流模型对提拉大直径单晶硅时,对晶体旋转、坩埚旋转及二者共同作用三种情况下,熔体内的流线、等温线、氧的浓度分布、紊流粘性系数、紊动能等作了数值模拟,发现晶体的旋转能提高氧的径向均匀性,紊流粘性系数和紊动能随着坩埚转速的提高先增加后下降.晶体坩埚同时旋转时并不能有效降低紊流粘性系数,但能使子午面上的流动受到抑制,等温线更为平坦,有利于晶体生长.     

钼酸铅单晶生长及其缺陷研究

本文通过CZ法生长钼酸铅单晶,讨论了温度梯度、拉速、转速等生长参数对晶体质量的影响,分析了晶体开裂、包裹物等宏观缺陷以及位错等微观缺陷的形成机理,并从晶体形态、包裹体和位错密度变化方面探讨了晶体生长参数与晶体缺陷之间的内在关系,从而优化温度梯度等生长参数.温度梯度为20～25℃/cm,晶体转速为28r/min,拉速为1.6mm/h时,生长出的晶体形态完整,无开裂现象,晶体中无气泡包裹体,位错密度明显减小,晶体尺寸达φ40mm×70mm,无散射颗粒,在波长0.42～5.5μm范围内,平均透光率为72.6;.     

Effect of impurities on the growth of {113} interstitial clusters in silicon under electron irradiation

The growth and shrinkage of interstitial clusters on {113} planes were investigated in electron irradiated Czochralski grown silicon (Cz-Si), floating-zone silicon (Fz-Si), and impurity-doped Fz-Si (HT-Fz-Si) using a high voltage electron microscope. In Fz-Si, {113} interstitial clusters were formed only near the beam incident surface after a long incubation period, and shrank on subsequent irradiation from the backside of the specimen. In Cz-Si and HT-Fz-Si, {113} interstitial clusters nucleated uniformly throughout the specimen without incubation, and began to shrink under prolonged irradiation at higher electron beam intensity. At lower beam intensity, however, the {113} interstitial cluster grew stably. These results demonstrate that the {113} interstitial cluster cannot grow without a continuous supply of impurities during electron irradiation. Detailed kinetics of {113} interstitial cluster growth and shrinkage in silicon, including the effects of impurities, are proposed. Then, experimental results are analyzed using rate equations based on these kinetics.     

高温超导衬底大尺寸LaAlO_3单晶体生长研究

铝酸镧(LaAlO3)单晶是超导研究领域使用最普遍的单晶体之一,详细介绍了采用下称重,CZ法(Czo-chralski)生长大尺寸(Φ80mm)LaAlO3单晶的工艺条件,并对影响晶体质量的主要因素进行了分析、讨论,给出了解决晶体质量问题的手段和有效途径。     

Characterization of a Czochralski grown silicon crystal doped with 1020 cm‐3 germanium

A dislocation‐free silicon single crystal doped with 10²⁰ cm^‐3 germanium (Ge) has been grown using the Czochralski (CZ) growth technique. The Ge concentration in the seed‐end and tang‐end of the crystal was 8×10¹⁹cm^‐3and 1.6×10²⁰ cm^‐3, respectively. The effective segregation coefficient of Ge, the distribution of flow pattern defects (FPDs) and the wafer warpage have been characterized. Both the effective segregation coefficient and the equilibrium segregation coefficient of Ge in silicon were evaluated. Then, the density of FPDs was traced from seed‐end to tang‐end of the ingot, a suppression of FPDs by Ge doping was shown. That is probably because the Ge atoms consume free vacancies and thus a higher density of smaller voids is formed. Furthermore, the mechanical strength of wafers has also been characterized by batch warpage analysis. The warpage in the seed‐end was larger than that in the tang‐end of the ingot, showing that the mechanical strength of wafers is enhanced by Ge doping. Such improvement is interpreted by an enhanced dislocation pinning effect associated with the enhanced nucleation of grown‐in oxygen precipitates in the Ge‐doped silicon wafers. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and spectroscopic characterization of Zr:Fe:LiNbO3 crystals with various Li/Nb ratios

In this paper, Zr:Fe:LiNbO₃ crystals with various Li/Nb ratios were grown by the Czochralski method from melts having compositions varying between 48.6 and 58 mol% Li₂O. X-ray powder diffraction (XRD), inductively coupled plasma optical emission/mass spectrometry (ICP-OE/MS), ultraviolet–visible (UV–vis) absorption and the infrared (IR) spectrum were measured and are discussed in terms of the spectroscopic characterization. It was found that as the Li/Nb ratio increases in the melt, the Li/Nb ratio in the crystal also increases, the distribution coefficients of Fe and Zr ions decrease, the absorption edge shifts to a shorter wavelength, and the ZrO₂ threshold concentration of the samples decreases.     

Three‐dimensional study of the pressure field and advantages of hemispherical crucible in silicon Czochralski crystal growth

The effects of several growth parameters in cylindrical and spherical Czochralski crystal process are studied numerically and particularly, we focus on the influence of the pressure field. We present a set of three‐dimensional computational simulations using the finite volume package Fluent in two different geometries, a new geometry as cylindro‐spherical and the traditional configuration as cylindro‐cylindrical. We found that the evolution of pressure which is has not been studied before; this important function is strongly related to the vorticity in the bulk flow, the free surface and the growth interface. It seems that the pressure is more sensitive to the breaking of symmetry than the other properties that characterize the crystal growth as temperature or velocity fields. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Simulation of temperature and flow fields in an inductively heated melt growth system

The goal of the research presented here is to apply a global analysis of an inductively heated Czochralski furnace for a real sapphire crystal growth system and predict the characteristics of the temperature and flow fields in the system. To do it, for the beginning stage of a sapphire growth process, influence of melt and gas convection combined with radiative heat transfer on the temperature field of the system and the crystal‐melt interface have been studied numerically using the steady state two‐dimensional finite element method. For radiative heat transfer, internal radiation through the grown crystal and surface to surface radiation for the exposed surfaces have been taken into account. The numerical results demonstrate that there are a powerful vortex which arises from the natural convection in the melt and a strong and large vortex that flows upwards along the afterheater side wall and downwards along the seed and crystal sides in the gas part. In addition, a wavy shape has been observed for the crystal‐melt interface with a deflection towards the melt. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Ce:Lu2Si2O7闪烁晶体的结构和光谱特性

采用中频感应提拉法生长出Ce:Lu₂Si₂O₇（Ce:LPS） 晶体. 通过x射线粉 末衍射分析，晶体结构属单斜晶系的C2/m空间群. 光学显微镜下可观测到晶体的（110 ）解理. 在室温下测试了Ce:LPS晶体的吸收光谱、激发光谱和发射光谱. 结果表明，Ce:LPS 晶体的吸收峰只有两个，分别位于302和349 nm，且与激发峰的位置一致，归因于Ce³⁺ 的4f¹→5d¹跃迁的特征吸收所致. 发射光谱具有Ce^{3+< /sup>典型的双峰特征 ，经Gaussian多峰值拟合，带状谱是由384和407 nm两个发射峰叠加而成，且后者的强度明 显高于前者. 关键词： 2Si₂O₇')" href="#">Ce:Lu₂Si₂O₇ 提拉法 晶体结构 光学 特性}