Implantation induced defects and electrical properties of Sb-implanted ZnO

Defects in Sb implanted Zn O single crystals have been studied by using photoluminescence(PL) spectroscopy,X-ray diffraction(XRD) and Raman scattering.Electrical properties of the samples were analyzed by Hall effect measurement.The results indicate that the annealed Sb-implanted sample is n-type with a free electron concentration of the same amplitude as the calculated implantation concentration.The well-known oxygen vacancy related deep level green PL band is suppressed in the as-implanted sample and recovers to the level close to the as-grown Zn O single crystal after annealing.These phenomena suggest that a large portion of as-implanted Sb atoms occupy oxygen lattice site in an unstable state and move to the interstitial site,forming the complex donor defect upon high temperature annealing,resulting in n-type conduction even if the implantation dose is quite high.     

氩等离子体诱导量子阱混合技术

研究了基于InGaAsP/InP应变多量子阱片的氩等离子体诱导量子阱混合工艺方法.当等离子刻蚀机（ICP）的射频(RF）功率为480 W、ICP功率为500 W、处理时间为1 min时,ICP处理过程中氩（Ar）等离子体对量子阱片的刻蚀深度小于牺牲层的厚度500 nm,晶格缺陷将产生在牺牲层内.样品在纯氮气条件、不同温度下快速退火2 min,缺陷扩散至量子阱层诱发量子阱混合.不同实验条件的样品PL光谱表明：随着退火温度和ICP功率的增加,量子阱片的光致发光谱（PL）峰值波长会发生显著的蓝移,分别在750 ℃和500 W时趋于饱和;此时获得的蓝移为110 nm,PL强度为原生片的55%,量子阱层仍保持了较好的晶格特性.     

UV-Vis and Photoluminescent Spectra of TiO_2 Films

1　IntroductionThestudyofTiO2 photocatalysthasbeenfocusedontheapplicationtopurificationandtreatmentofairandwater[1,2 ] .ManymethodshavebeenusedtoprepareTiO2filmssuchassol gelprocess ,CVD ,sputteringandsoon[2 -4] .Amongthem ,reactivesputteringisoneofthemostunitizedmethodsforobtaininguniformthinfilmswithawell controlledstoichiometry[3 ,5] .Whenonecon sidersphotocatalyticapplications ,animportantaspectofTiO2 film ,besidesthecrystallinephase (anatase) ,isthepresenceofoxygenvacancy[6] .Takedaet…     

UV-vis and photoluminescent spectra of TiO<Subscript>2</Subscript> films

TiO₂ fims have been deposited on glass substrates using DC reactive magnetron sputtering at different oxygen partial pressures from 0. 10 Pa.to 0.65 Pa. The transmittance (UV-vis) and photoluminescence (PL) spectra of the films were recorded. The results of the UV-vis spectra show that the deposition rate of the films decreased at oxygen partial pressure P(O₂)≥0.15 Pa, the band gap increased from 3.48 eV to 3.68eV for direct transition and from 3.27 eV to 3.34 eV for indirect transition with increasing the oxygen partial pressure. The PL spectra show convincingly that the transition for films was indirect, and there were some oxygen defect energy levels at the band gap of the films. With increasing the O₂ partial pressure, the defect energy levels decreased. For the films sputtered at 0.35 and 0.65 Pa there were two defect energy levels at 2.63 eV and 2.41 eV, corresponding to 0.72 eV and 0.94 eV below the conduction band for a band gap of 3.35 eV, respectively. For the films sputtered at 0.10 Pa and 0.15 Pa, there was an energy band formed between 3.12 eV and 2.06 eV, corresponding to 0.23 eV and 1.29 eV below the conduction band. ZHAO Qing-nan : Born in 1963 Funded by Natural Science Foundation of Hubei Province, China.     

Microwave absorbing properties and magnetic properties of different carbon nanotubes

The microwave absorbing properties and magnetic properties of as-grown Fe-filled carbon nanotubes (CNTs), annealed Fe-filled CNTs, and multi-walled CNTs were studied. Vibrating sample magnetometer results showed that the annealed Fe-filled CNTs have the weakest coercivity and strongest saturation magnetization among the three types CNTs, due to the presence of more ferromagnetic α-Fe nanowires. After annealing, the values increased to 291.0 Oe and 28.0 emu/g and the samples showed excellent microwave absorbing properties. The reflection loss was over 5 dB between 11.6 GHz and 18 GHz with a maximum value of 10.8 dB for annealed Fe-filled CNTs (1.1 wt%)/epoxy composite.     

ZnO films on transferable and low thermal resistance graphite substrate grown by ultrasonic spray pyrolysis

ZnO thin films were deposited on graphite substrates by ultrasonic spray pyrolysis method with Zn(CH 3 COO) 2 ·2H 2 O aqueous solution as precursor. The crystalline structure, morphology, and optical properties of the as-grown ZnO films were investigated systematically as a function of deposition temperature and growth time. Near-band edge ultraviolet(UV) emission was observed in room temperature photoluminescence spectra for the optimized samples, yet the usually observed defect related deep level emissions were nearly undetectable, indicating that high optical quality ZnO thin fi lms could be achieved via this ultrasonic spray pyrolysis method. Considering the features of transferable and low thermal resistance of the graphite substrates, the achievement will be of special interest for the development of high-power semiconductor devices with suffi cient power durability.     

硅中氧沉淀缺陷类型的控制及其在加工过程中的变化

本文研究了不同退火条件下,硅中氧沉淀缺陷类型的变化。实验结果表明,棒状缺陷和点状缺陷的数量比随低温成核退火时间的增加而减小;对于相同的成核时间,棒状缺陷和点状缺陷的比随成核温度增加开始上升,后来下降。在不同气氛和不同表面复盖情况下退火,发现在表面发生氧化时,缺陷尺寸随距洁净区距离的缩短而增加,而且缺陷尺寸的变化程度与氧化情况有关;在不发生氧化时,体内点状缺陷基本不变。     

FeS<Subscript>2</Subscript> (pyrite) electrodeposition thin films and study of growth mechanism

With the development of semiconductor solar cells, much attention has been focused on the low-cost, high-performance photovoltaic materials for solar cell fabrications. Sul-fide compounds[1,2], due to their desirable optical properties, were widely used in pre-paring solar cells. Although the Cd-based II-VI compounds solar cell, such as CdS, CdTe, etc.[3,4], processes a higher conversion efficiency than the sulfide-based solar cell does. The iron pyrite (FeS2) characteristic of suitable ba…     

单线阵CCD系统的表面凹坑缺陷检测方法

为解决表面凹坑缺陷与其他平面表面缺陷同时在线检测的问题,提出一种基于单线阵CCD系统进行表面凹坑缺陷检测的方法．根据光辐射照射模型和相机成像模型,建立了基于单线阵CCD的凹坑检测数学模型,由模型推导出图像像素灰度与凹坑深度的关系,利用特定光源和光照角度的关系,进行表面凹坑缺陷的检测．结果表明,由于凹坑边缘部位深度的渐变引起CCD输出电压信号的渐变,凹坑图像呈现边缘像素灰度渐变现象,且随光源光照角度的降低,凹坑图像特征更加突出．边缘灰度渐变的图像特征成为凹坑缺陷与其他平面缺陷相区别的重要特征,有利于凹坑缺陷的检测与识别．     

等离子束辅助沉积制备ZnO薄膜的特性研究

采用等离子束辅助沉积的方法在n-Si(001)衬底上制备出ZnO薄膜。X射线衍射谱显示，所制备的ZnO薄膜有较强的(002)晶面衍射峰，表明ZnO薄膜为c轴择优取向生长的，并且随着退火温度升高，晶粒逐渐增大，衍射峰逐渐增强。光致发光谱测量发现，样品分别在3．28eV和2．48eV存在紫外发射和深能级发射两个较强的发射峰，并且随着退火温度升高，深能级发射逐渐减弱，紫外发射峰得到进一步改善。四探针测试电阻率结果表明，随着退火温度的升高，ZnO薄膜的电阻率呈线性增加。     

MoS 2 中带电点缺陷性能的理论研究

采用一个严谨的、透明的、与体系维度无关的带电缺陷计算理论 TRSM 模型,系统研究了 MoS 2 中点缺陷的形成能。研究结果表明,单层 MoS 2 的所有 n 型或 p 型固有缺陷电离能级都很深,并且 S 空位（V S ）缺陷也不是实验观察到的 n 型导电性的起源。相反,H 原子吸附在 MoS 2 中具有非常低的离化能, 可能是 MoS 2 具有 n 型导电性的原因。     

压力容器中体积缺陷工程评定方法的研究

本文采用基本突然损伤模型的有限元分析研究了体积型缺陷的工程评定方法,提出将体积型缺陷简化为平面缺陷,并采用常用规范对简化后的平面缺陷进行工程评定的方法,本文还研究了共面平面缺陷的复合及自由表面对缺陷的影响问题。计算结果表明,该方法是安全的,可用于缺陷的工程评定。     

离心铸造铸铁汽室套白斑组织的研究

白斑是离心铸造厚壁铸铁缸套的一种异常组织。本文以机车汽室套为例,通过化学成分、显微组织、硬度和电子显微镜微区成分分析以及生产统计资料,研究了白斑的显微组织特点,探讨了白斑组织的形成机理,并提出了解决白斑缺陷的工艺措施。     

Electric properties of Ge quantum dot embedded in Si matrix

The electric characteristics of Ge quantum dot grown by molecular beam epitaxy in Si matrix were investigated by admittance spectroscopy and deep level transient spectroscopy. The admittance spectroscopy measurements show that the activation energy of 0.341 eV can be considered as the emitting energy of hole from the ground state of the quantum dot. And the capacitance variation with temperature of the sample shows a platform at various frequencies with reverse bias 0.5 V, which indicates that the boundary of space charge region is located at the quantum dot layer where the large confined hole concentration blocks the further extension of space charge region. When the temperature increases from 120 K to 200 K, the holes in the dot emit out completely. The position of the platform shifting with the increase of the applied frequency shows the frequency effects of the charges in the quantum dot. The deep level transient spectroscopy results show that the charge concentration in the Ge quantum dot is a function of the pulse duration and the reverse bias voltage, the activation energy and capture cross-section of hole decrease with the increase of pulse duration due to the Coulomb charging effect. The valence-band offsets of hole in Ge dot obtained by admittance spectroscopy and deep level transient spectroscopy are 0.341 and 0.338 eV, respectively.     

光伏航拍红外图像的热斑自动检测方法

针对光伏电站传统巡检技术的高成本、低效率以及准确率不高等问题,提出二阶段式的航拍红外图像热斑检测方法,实现对红外图像中热斑缺陷的组件级定位及精细化分类诊断. 该方法将传统图像处理技术与深度学习方法融合,进一步提升缺陷诊断的准确率与效率. 基于航拍红外图像前、后景灰度值的差异,提出基于边缘检测的组件分割方法来提取光伏组件轮廓以实现组件级定位,该方法以相对较小的硬件需求实现光伏组件有效检出率可达99.3%. 考虑到热斑成因、危害及对应处理方式的差异性,提出基于EfficientNet的红外缺陷分类模型对热斑进行精细的四分类,为电站运维人员提供更为精准的决策支撑,该模型在空间占用20.17 MB的情况下获得97.0%的热斑分类准确率. 经过实验对比分析,论证了本研究所提出的方法在缺陷诊断的效率以及准确率上都较高.     

半绝缘GaAs退火前后深能级的研究

用TSDC(热激去极化电流)法对半绝缘砷化镓(SI-GaAs)退火前后的深能级进行了测量,并对该方法进行理论分析,推导出这一热激过程的动力学方程。用曲线拟合的方法对陷阱能量E等拟合,理论与实验结果吻合。测得SI-GaAs:Cr样品中Cr产生的深能级为E_c-0.716eV,Ec-0.532eV;高纯SI-GaAs样品中EL_2能级为E_c-0.735eV。另外,还测得其它几个深能级。     

石墨烯/h-BN面内异质结构热输运的分子动力学研究

采用非平衡分子动力学方法探究石墨烯/h-BN面内异质结构界面热导的影响因素,讨论了单空位缺陷和Stone-Wales (SW)缺陷在近界面不同位置时的声子热输运活动。模拟结果证明,当h-BN一侧单空位缺陷远离界面,界面热导随之降低; SW缺陷则由共价键类型和位置决定其对界面热导的影响,由此揭示缺陷的类型和位置对界面热导带来的调节作用。此外,讨论了界面处存在单空位缺陷时,温度变化影响界面热导背后的潜在机理。本研究对微观尺度下的二维异质结构材料的热导性能提供理论参考和实验指导。     

灰铸铁件小缺陷焊补的研究

介绍了灰铸铁件小缺陷的特殊性,从焊补工艺上和材料的选用２两方面考虑,有效地降低了焊接裂纹的产生,使母材与焊被金属熔合良好,在试验的基础上,提出了灰铸铁件小缺陷焊补的新材料和新工艺。     

AZ31镁合金板冷拉深变形特点

在室温条件下,对最常用的镁合金AZ31板材在经过不同的退火热处理后进行冷拉深试验研究中,借助有限元数值模拟技术对其拉深变形过程进行分析,探索其冷拉深变形特点及规律,并合理解释在拉深过程中的载荷特点、破裂形态、极限拉深比、各向异性现象、厚度分布规律以及退火工艺条件、模具结构及尺寸对它们的影响规律.     

复杂载荷下含体积性缺陷弯管的塑性极限载荷

通过非线性有限元分析给出了含体积性缺陷弯管在内压、面内弯矩、面外弯矩和扭矩作用下的塑性极限载荷。对与体积型缺陷（长轴、短轴和深度）和管线（外径、壁厚和弯曲半径）有关的几何变量进行了系统的分析,并考虑了内压和面内弯矩、面外弯矩和扭矩的组合。结果表明壁厚、缺陷深度和缺陷方向对极限载荷影响较大。