Defect behaviors in n-channel power VDMOSFETs during HEFS and thermal post-HEFS annealing

The results of positive/negative Fowler-Nordheim high electric field stress and thermal post-high electric field stress annealing of commercial n-channel power VDMOSFETs have been presented. They have shown that gate bias sign has an influence on the fixed trap behavior during high electric field stress, but has no influence on any defect type behavior during thermal post-high electrical field stress annealing. In addition, slow switching traps have different behavior, but fast switching traps have the same behavior during thermal post-high electrical field stress annealing and thermal post-irradiation annealing.     

Relationship of annealing time and intrinsic defects of unintentionally doped 4H-SiC

With annealing temperature kept at 1573 K, the effects of annealing time on stability of the intrinsic defects in epitaxial unintentionally doped 4H-SiC prepared by low pressure chemical vapour deposition have been studied by electron spin resonance (ESR) and low temperature photoluminescence. This paper reports the results shown that annealing time has an important effect on the intrinsic defects in unintentionally doped 4H-SiC when annealing temperature kept at 1573 K. When the annealing time is less than 30 min, the intensity of ESR and photoluminescence is increasing with annealing time prolonged, and reaches the maximum when annealing time is 30 min. Then the intensity of ESR and photoluminescence is rapidly decreased with the longer annealing time, and much less than that of as-grown 4H-SiC when annealing time is 60 min, which should be related with the interaction among the intrinsic defects during the annealing process.     

非故意掺杂4H-SiC外延材料本征缺陷的热稳定性

采用电子顺磁共振（ESR）和低温光致发光（PL）技术,研究了退火温度对低压化学气相沉积法（LPCVD）制备的非故意掺杂 4H-SiC材料中本征缺陷稳定性的影响.结果发现,当退火时间为10 min和30 min时,本征缺陷浓度均随着退火温度的升高而增大,当退火温度达到1573 K时材料中本征缺陷浓度达到最大,继续升高退火温度将使材料中本征缺陷浓度迅速降低.退火温度对材料中本征缺陷的影响主要是由于退火中本征缺陷的稳定化过程及本征缺陷之间发生强烈的相互作用引起的. 关键词： 高温退火 本征缺陷 电子顺磁共振谱 光致发光     

Growth kinetics of titanium silicide during heating by RTA and furnace annealing

A comparison of growth kinetics of titanium silicide obtained from the reaction of titanium layers on silicon after heating either by conventional thermal annealing or by rapid thermal annealing (RTA) has been undertaken. Very close results have been found for both treatments when sufficient care has been taken to avoid oxygen contamination during any step of the process. This indicates that no enhanced silicidation reaction is due to RTA itself. However, for oxygen contaminated samples, the kinetics remains essentially the same for RTA while it is showed down for furnace annealing. Then in contrast with conventional annealing, RTA is able to reduce the oxygen influence and to give the real kinetics even on samples containing large amounts of oxygen.     

Influence of rapid thermal annealing on the specific features of defect generation in silicon wafers during the formation of effective internal getters

The specific features of the defect generation in silicon wafers subjected to a rapid thermal annealing during the formation of an internal getter have been investigated using optical microscopy and transmission electron microscopy. It has been established that rapid thermal annealing leads to a significant intensification of the decomposition of a supersaturated solid solution of oxygen in silicon, especially in the central region of the wafer. This intensification is responsible for the appearance of characteristic differences in sizes, densities, and morphological features of the microdefects generated in the samples subjected to a rapid thermal annealing as compared to the samples after a conventional heat treatment. The results obtained have demonstrated that the use of rapid thermal annealing has undoubted advantages in the formation of effective internal getters in silicon wafers.     

具有纳米氧化层的磁性隧道结的热稳定性研究

研究发现在磁隧道结的反铁磁层和被钉扎铁磁层之间插入一层纳米氧化层，可以使磁隧道结的退火温度增加了40℃，即明显地提高了磁隧道结的温度稳定性.通过卢瑟福背散射实验直接观察到产生这一效应的原因是该纳米氧化层有效地抑制了Mn元素在退火过程中的扩散，从而使TMR值在较高的退火温度下得以保持. 关键词： 磁性隧道结 隧穿磁电阻 热稳定性 纳米氧化层     

材料中He深度分布演化的Monte Carlo模拟研究

基于He泡生长的迁移-合并机理,用Monte Carlo方法模拟了对材料进行等温退火过程中He深度分布的演化,探讨了不同参数对这一演化的影响.研究表明:材料中He泡的初始浓度和尺寸将影响He深度分布的变化,而退火温度则对演化速率起重要作用但对最终的He深度分布影响较小;随着反应的进行,整个系统的演化是逐渐趋缓的. 关键词： He 深度分布 Monte Carlo模拟     

The electrical properties of thin permalloy films

The magnetic properties of thin Permalloy films have been the subject of many investigations, but the work on their electrical properties is very limited [1]. By observing the change in electrical resistance with temperature the structural transformations taking place during the annealing of the condensates can be inferred.The authors of [1] did not undertake a detailed study of the electrical properties of Permalloy. They used Permalloy 79NMA in their investigation, and the dependence of the change in electrical resistance on the temperature of annealing in a magnetic field enabled them to reach conclusions about the nature of the uniaxial anisotropy of thin films.In the present work a detailed study has been made of the electrical resistance of Permalloy films in relation to the temperature of the substrate during evaporation and annealing; the temperature coefficient of resistance (TCR) has also been studied.     

Peculiarities of post-irradiation annealing of MgO crystals

The influence of high-temperature annealing on absorption spectra of nominally pure and impure MgO crystals irradiated in a nuclear reactor has been investigated. In nominally pure crystals, as a whole, the accumulation of defect aggregates of non-monotonous character takes place during the whole cycle of the action of radiation plus post-irradiation annealing: the creation of defects in the process of irradiation, their destruction by annealing at 700 °C and repeated creation at higher annealing temperature. In irradiated impure crystals, where the mentioned defects exist in larger quantities, their thermal reanimation is not observed after the decay at 700 °C.     

Rapid thermal annealing of high dose arsenic-implanted silicon

A model for rapid thermal annealing of high dose arsenic-implanted silicon layers is proposed. The kinetics of arsenic clustering was taken into account. Assuming that all arsenic is initially electrically active, the clustering rate is found to be enhanced during the early stage of annealing in comparison with results reported for conventional furnace tempering [1]. An influence of a low temperature preannealing on the diffusion behaviour of arsenic has not been observed.     

Characterization of Cd implanted and annealed GaAs and InP by perturbed angular correlation (PAC) spectroscopy

Investigations of ^111mCd implanted GaAs and InP crystals using the microscopically sensitive perturbed angular correlation technique show that the implanted Cd is incorporated on unperturbed substitutional lattice sites during rapid thermal annealing at significant lower temperatures than for electrical activation is required. In GaAs the higher implantation temperature at 473 K did not show any influence on this annealing stage, whereas as higher implantation dose hinders the annealing. We conclude that not only the local environment of the implant but also the long-range lattice perfection has to be restored for the electrical activation of implants in III-V compound semiconductors.     

Radiation damage by implanted ions in GaAs and GaP

Abstract

The production of lattice disorder in GaAs and GaP by Te ions up to 40 keV has been investigated. For GaAs the build up of damage with implanted ion dose is linear until a saturation level is reached. For Gap, two linear regions are evident; a slow build up of damage to ?15 per cent of the saturation level, followed by a faster rate of increase up to the final 100 per cent level. Radiation annealing, for GaP samples, both by the heavy ion beam during implantation and by the helium beam during back-scattering measurements has been observed. The annealing temperatures required for re-ordering the lattice depend on the percentage of damage present. Samples damaged up to the saturation level require annealing at ?500°C, whilst 300°C is sufficient for samples damaged to ?50 per cent of the saturation value.     

Transformation of point defects in silicon dioxide during annealing

In our previous studies, we have demonstrated that annealing of silicon dioxide in the absence of oxygen leads to the formation of silicon clusters near the surface. The mechanism of the formation of silicon clusters by this technique has not been sufficiently investigated. However, it has been found that the rate of the formation of nanoclusters and their sizes depend on the concentration of point defects in the silicon dioxide and on the concentration of impurities, for example, hydroxyl groups. As a continuation of these studies, in the present work we have investigated changes in the concentration of point defects in silicon dioxide films during high-temperature annealing. A new method has been proposed for the evaluation of changes in the concentration of point defects in silicon dioxide films before and after annealing. A model of the transformation of point defects in silicon dioxide into silicon nanoclusters due to the high-temperature annealing has been developed.     

Enhancement of Photoluminescence Intensity of GaInNAs/GaAs Quantum Wells by Two-Step Rapid Thermal Annealing

We investigate the effect of rapid thermal annealing on InGaNAs/GaAs quantum wells. At optimized annealing temperatures and times, the greatest enhancement of the photoluminescence intensity is obtained by a special two-step annealing process. To identify the mechanism affecting the material quality during the rapid thermal annealing, differential temperature analysis is applied, and temperature- and power-dependent photoluminescence is carried out on the samples annealed under different conditions. Our experiment reveals that some composition redistribution or other related ordering processes may occur in the quantum-well layer during annealing. Annealing at a lower temperature for a long time primarily can remove defects and dislocations while annealing at a higher temperature for a short time primarily homogenizes the composition in the quantum wells.     

Anomalous thermal bleaching of color centers in calcium fluorapatite

A study has been made of the radiation-induced paramagnetic color centers in calcium fluorapatite on annealing. It is found that there is an anomalous increase in the center concentration during isothermal annealing. An explanation is given via a model for diffusion of point defects and groups involving charge redistribution. It is found that the dislocation structure affects the thermal bleaching of the color centers.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 34–37, April, 1975.     

DLTS studies of deep levels in semiconducting N-CdTe single crystals

Deep levels created by annealing of Al-doped n-CdTe single crystals have been studied by the Deep Level Transient Spectroscopy (DLTS) technique. Eight levels have been detected in the energy range from 0.04 to 0.07 eV below the conduction band edge. The thermal ionization energies and the capture cross sections for electrons in these levels have been obtained. The dependence of concentrations of the levels on the Cd vapor pressure during annealing and on the cooling process after annealing has been determined.     

Relaxation of the state with induced transverse magnetic anisotropy in the soft magnetic nanocrystalline alloy Fe73.5Si13.5Nb3B9Cu1

The residual lattice strains of nanocrystals, which are responsible for the formation of states with transverse magnetic anisotropy in samples of the Fe-Si-Nb-B-Cu alloys (Finemets) subjected to annealing under tensile loading with the subsequent relaxation annealing at temperatures in the range from 500 to 600°C, have been measured using X-ray diffraction. The relative extension and compression of interplanar spacings have been compared with the induced magnetic anisotropy constants determined from the magnetic hysteresis loops. It has been shown that, during the relaxation annealing at the nanocrystallization temperature (500?C540°C), the observed decrease in the residual strains is accompanied by a decrease in the transverse magnetic anisotropy constant. A linear correlation between the relative extension and compression of the interplanar spacings for different crystallographic planes and magnetic anisotropy constant has been revealed. The deviation from linearity is observed after annealing at a temperature of 600°C, which is explained by a possible increase in sizes of nanocrystals, changes in their structure, and partial crystallization of the amorphous matrix.     

Change in the substructure of cold worked aluminum crystals on subsequent heating

In this research, a relationship has been established between the polygonization of aluminum single crystals on annealing and the hardening curve for single crystals of fec metals. It has been shown by the Guinier-Tennevin X-ray focusing method that only high-temperature (600–640 °C) polygonization develops on annealing single crystals of pure (99.99%) aluminum cold worked by extension at –196 °C within stages I and II of the hardening curve. In crystals cold worked to the end of stage II, and in the whole of stage III, the polygonization process takes place at an appreciable rate even during low-temperature (450 °C) annealing. Subsequent high-temperature annealing of these single crystals leads to an increase in the degree of perfection of the crystal lattice of the subgrains whose formation began during low-temperature annealing.     

低温退火对重掺砷直拉硅片的氧沉淀形核的作用

通过对比研究重掺砷直拉硅片和轻掺n型直拉硅片经过低温(450—800℃)和高温(1000℃)两步退火的氧沉淀行为,阐明了低温退火对重掺掺砷直拉硅片的氧沉淀形核的作用.研究指出：重掺砷硅片在450℃和650℃退火时的氧沉淀形核比在800℃退火时更显著,这与轻掺硅片的情况截然相反;此外,与轻掺硅片相比,重掺砷硅片在450℃和650℃退火时氧沉淀的形核得到增强,而在800℃退火时氧沉淀的形核受到抑制.分析认为,重掺砷硅片在450℃和650℃退火时会形成砷-空位-氧(As-V-O)复合体,它们促进了 关键词： 重掺砷直拉硅片 氧沉淀形核 低温退火     

Extended defects in hydrogen-implanted (111) silicon wafer treated by high temperature annealing process

Hydrogen impurity has been an active topic of research in material science and en-gineering[1—3]. Many studies indicated that chemically active hydrogen can affect theproperties of the materials including silicon. For example, hydrogen may lead to theembrittlement of silicon crystals[4] and the passivation of the deep-level impurities[5].More interestingly, high dose of hydrogen in silicon by ion implantation can evidentlychange the material structure. {111} and {100} platelet defects were ob…