Molecular dynamics study on splitting of hydrogen-implanted silicon in Smart-Cut® technology

Defect evolution in a single crystal silicon which is implanted with hydrogen atoms and then annealed is investigated in the present paper by means of molecular dynamics simulation. By introducing defect density based on statistical average, this work aims to quantitatively examine defect nucleation and growth at nanoscale during annealing in Smart-Cut~ technology. Research focus is put on the effects of the implantation energy, hydrogen implantation dose and annealing temperature on defect density in the statistical region. It is found that most defects nucleate and grow at the annealing stage, and that defect density increases with the increase of the annealing temperature and the decrease of the hydrogen implantation dose. In addition, the enhancement and the impediment effects of stress field on defect density in the annealing process are discussed.     

Relaxation of a defect subsystem in silicon irradiated with high-energy heavy ions

The relaxation of a silicon defect subsystem modified by the implantation of high-energy heavy ions was studied by varying the electrical properties of irradiated Si crystal annealed at a temperature of 450°C. It is shown that quenched-in acceptors are introduced into Si crystals as a result of irradiation with comparatively low doses of Bi ions and subsequent relatively short annealing (no longer than 5 h); the distribution of these quenched-in acceptors has two peaks located at a depth of about 10 μm and at a depth corresponding approximately to the ions’ projected range (43.5 μm). The peaks in the distribution of quenched-in acceptors correspond to the regions enriched with vacancy-containing defects. As the heat-treatment duration increases, the acceptor centers are transformed into donor centers with the centers’ spatial distribution remaining intact. Simultaneously, an almost uniform introduction of quenched-in donors occurs in the entire crystal beyond the depth corresponding to the projected range of ions. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 37, No. 5, 2003, pp. 565–569. Original Russian Text Copyright ? 2003 by Smagulova, Antonova, Neustroev, Skuratov.     

Influence of radiation defects on diffusion of arsenic and antimony in implanted silicon

Diffusion of implanted Sb and As in silicon layers with various contents of radiation defects is investigated during furnace thermal annealing and rapid thermal annealing (RTA). The defect concentration was varied by the additional introduction of Si⁺ ions. As the defect concentration in the layer increases, the antimony diffusivity increases both during lamp annealing and during furnace thermal annealing, which is governed by diffusion over excess vacancies. The As diffusivity increases with an increase in the concentration of radiation defects in the layer during the lamp annealing and decreases during furnace thermal annealing. The increase in the As diffusivity during RTA is attributed to interstitial Si atoms. The observed decrease in the As diffusivity is caused by the impurity capture by excess vacancies as the traps. However, at defect concentrations much higher than the impurity concentration, the As diffusivity increases but remains substantially lower than the intrinsic value. It follows from the results that the rate of intrinsic As diffusion along the interstitial channel is higher than along the vacancy channel.     

Defect formation in PbTe under the action of a laser shock wave

Mechanisms of the defect formation in PbTe thin films on BaF₂ substrates under shock-wave action are studied, and the kinetics of the annealing of the resulting nonequilibrium crystal defects at room temperature is analyzed. The respective roles of the first-and second-order annealing reactions in settling of the equilibrium state of the defects are estimated. The contributions of Frenkel pair annihilation in both sublattices and migration of interstitials to sinks to a change in the total concentration of nonequilibrium defects at different stages of annealing are considered.     

Defect engineering in implantation technology of silicon light-emitting structures with dislocation-related luminescence

Results obtained in development of physical foundations of ion implantation technology for fabrication of silicon light-emitting structures (LESs) based on dislocation-related luminescence and intended for operation at wavelengths close to ∼1.6 μm are summarized. The development of the concept of defect engineering in the technology of semiconductor devices makes it possible to determine the fundamental aspects of the process of defect formation; reveal specific features of the emission spectra related to changes in the implantation conditions of Er, Dy, Ho, O, and Si ions and the subsequent annealing; and design light-emitting structures with a desirable spectrum of luminescent centers and extended structural defects. The technological conditions in which only a single type of extended structural defect (Frank loops, perfect prismatic loops, or pure edge dislocations) is introduced into the light-emitting layer are found, which enables analysis of the correlation between the concentration of extended defects of a certain type and the intensity of lines of the dislocation-related luminescence. The key role of intrinsic point lattice defects in the origination and transformation of extended structural defects and luminescent centers responsible for the dislocation-related luminescence is revealed. It is found that the efficiency of luminescence excitation from the so-called D1 centers, which are of particular interest for practical applications, varies by more than two orders of magnitude between structures fabricated using different technological procedures. High-efficiency silicon light-emitting diodes with room-temperature dislocation-related luminescence have been fabricated.     

Special features of optical and photoelectric properties of nominally undoped and Cu-doped CdS single crystals

Experimental data on the effect of fast reactor neutrons on the absorption spectra, photoconductivity, and luminescence of nominally undoped and Cu-doped CdS single crystals are reported. It is shown that defect clusters formed as a result of neutron irradiation exhibit the properties of getters for easily migrating optically active impurities in the crystal lattice. In neutron-irradiated samples, the defects can be annealed in two stages. The first stage (100–150°C) involves the annealing of point defects, while the second stage (250–420°C) involves mainly the annealing of defect clusters. The degradation of the defect clusters is accompanied with the enrichment of the lattice with Cd and S vacancies.     

热处理中As压对半绝缘GaAs缺陷的影响

在 95 0°C和 1 1 2 0°C温度下 ,对非掺杂半绝缘 LECGa As进行了不同 As气压条件下的热处理 ,热处理的时间为 2～ 1 4小时。发现不同 As压条件下的热处理可以改变 Ga As晶片的化学配比 ,并导致本征缺陷和电参数的相应变化。在 95 0°C和低 As气压条件下进行 1 4小时热处理 ,可在样品体内 (表面 1 5 0 μm以下 )引入一种本征受主缺陷 ,使电阻率较热处理前增加约 5 0 % ,霍尔迁移率下降 70 %。这种本征受主缺陷的产生是由于热处理过程中样品内发生了 As间隙原子的外扩散。提高热处理过程中的 As气压可以抑制这种本征受主缺陷的产生。真空条件下在 1 1 2 0°C热处理 2～ 8小时并快速冷却后 ,样品中的主要施主缺陷 EL2浓度约下降一个数量级 ,提高热处理过程中的 As气压可以抑制 EL2浓度下降。这种抑制作用是由于在高温、高 As气压条件下 ,发生了间隙原子向样品内部的扩散     

Special features of the mechanism of defect formation in CdS single crystals subjected to irradiation with high doses of fast reactor neutrons

Electrical and optical properties of CdS single crystals irradiated with a dose ≥10¹⁸ cm^?2 of fast reactor neutrons have been studied. It is established that clusters of defects are formed in irradiated material, and cadmium vacancies are dominant in these clusters. In the case when the defect clusters are decomposed in the course of radiation-stimulated annealing or thermal annealing in the temperature range Φ ≈ (200–400)°C, the crystal lattice becomes enriched with Cd vacancies. It is assumed that subthreshold effects play an important role in formation of defect clusters, and that these effects are related to preferential excitation of the K shells in Cd atoms and their Coulomb ejection from the core of a cluster.     

液晶显示器Mura缺陷及测量方法浅析

Mura缺陷是液晶显示器(LCD)中常见的不良现象,直接影响到显示图像质量.本文对液晶显示器Mura缺陷进行了详细的综述,首先概述了Mura缺陷的种类及主要来源,然后介绍了Mura缺陷的三类测量方法:人工视觉识别法、电学测量法、光学测量法.人工视觉识别法利用滤光片观察样品,成本较低,但无法做到客观的评定产品等级;电学测量法适用于电气缺陷造成的Mura;基于机器视觉的光学测量法是当前研究的热点,对于各种原因造成的Mura缺陷均具有良好的检测效果.详细分析了各种检测方法的特点,最后进行归纳总结.     

含负折射率材料的1维光子晶体掺杂缺陷模研究

为了研究含有负折射率材料的光子晶体掺杂缺陷模的光学传输特性,利用传输矩阵理论进行数值分析。采用插入和替代两种方式对排列整齐的光子晶体进行掺杂,产生了缺陷模式。结果表明,引入正折射率缺陷只能在布喇格带隙中产生缺陷模,引入负折射缺陷能够同时在全方位光子带隙和布喇格带隙中产生缺陷模。同时研究了掺杂方式、入射方向、缺陷厚度、缺陷位置、缺陷类型对缺陷模式的影响,并对含有两层缺陷的光子晶体进行研究,得到两缺陷层的距离与带隙产生的关系,即距离越近越容易产生缺陷模式,且缺陷模的深度越深。这对于制造新型的全方位滤波器是有指导作用的。