用MEVVA低能离子注入制备表层SiC/Si异质结构及其室温的光致发光特性

利用金属蒸汽真空弧离子源（MEVVA）进行离子束合成,制备了过剂量C^＋离子注入到单晶硅衬底的样品。然后利用热退火,在表层制备了连续8-SiC层,形成表层SiC／Si的异质结构。利用傅里叶变换红外光谱（FTIR）对其成键特征和微结构进行了分析,通过光电子能谱分析（XPS）和原子力显微镜（AFM）分析了样品的成分分布及其表面形貌。最后对其室温下的光致发光特性随热退火的时间和温度的变化进行了研究。结果表明：光致发光谱（PL）表现出430,560nm两个发光峰,分别对应于纳米碳化硅和块状立方碳化硅发光的特征峰。我们认为小颗粒的晶化碳化硅的尺寸及其相对比例对PL发光峰位和强度有较大的影响,用纳米晶粒量子效应（NSUQC）理论和表面态理论对发光现象及其变化规律进行了初步的解释。     

钛酸锶钡薄膜的室温光学性能研究

采用溶胶-凝胶法制备了(Ba0.75Sr0.25)TiO3薄膜,研究了不同退火温度下样品的物相结构、薄膜的光致发光性能和光学透过率。结果表明:室温下非晶钛酸锶钡薄膜在蓝光激发下具有明显的发光现象,发光波长范围是500～650 nm,峰值在525 nm附近。延长非晶态薄膜的退火时间能够显著提高样品的发光强度,且发光强度随薄膜厚度增加而增大。晶态薄膜有微弱的发光现象。透射谱测试结果表明,钛酸锶钡薄膜在可见光范围内具有良好的光学透过率。     

脉冲激光退火纳米碳化硅的光致发光

采用XeCl准分子脉冲激光退火技术制备了纳米晶态碳化硅薄膜(nc-SiC),并对薄膜的光致发光(PL)特性进行了分析。结果表明,纳米SiC薄膜的光致发光表现为300～600 nm范围内的较宽发光谱带,随退火激光能量密度的增加,nc-SiC薄膜398 nm附近的发光峰相对强度增加,而470 nm附近发光峰相对减小。根据nc-SiC薄膜的结构特性变化, 认为这两个发光峰分别来源于6H-SiC导带到价带间的复合发光和缺陷态发光,并且这两种发光过程存在竞争。     

非晶SiC_xO_y薄膜的可调强光发射机制

采用甚高频等离子体增强化学气相沉积技术,以SiH_4、CH_4和O_2作为反应气源,通过调控O2流量在250℃下制备强光发射的非晶SiC_xO_y薄膜。利用光致发光光谱、荧光瞬态谱、Raman光谱、X射线光电子能谱及红外吸收谱对薄膜的光学性质和微结构进行表征与分析,进而讨论其可调可见光发射机制。实验结果表明,SiC_xO_y薄膜发光性质与薄膜中的氧组分密切相关。随着薄膜中氧组分的增加,其发光峰位由橙红光逐渐向蓝光移动,肉眼可见强的可见光发射。荧光瞬态谱分析表明,薄膜的荧光寿命在纳秒范围。结合X射线光电子能谱和红外吸收谱对薄膜的相结构和化学键合结构进行分析,结果表明薄膜的主要相结构和发光中心随O_2流量的变化是其可调光发射的主要原因。     

薄膜光学 薄膜光学理论与膜系设计

O484.12007043566非晶碳化硅材料与光学微腔的制备与发光=Preparationand luminescence of amorphous SiC material andits opticalmicrocavity[刊,中]/陈德媛(南京大学物理系,固体微结构物理国家重点实验室.江苏,南京(210093)),钱波…//发光学报.?2007,28(1).?121-125利用等离     

ZnO薄膜表面和边缘的发光特性

研究了分子束外延方法生长的ZnO薄膜的光学特性,首先测量样品反射光谱,然后重点研究其光致发光光谱。实验中通过改变激发光的强度,以及采用波导配置和不同的实验几何配置等手段,观察到了ZnO薄膜中起源于激子-激子散射和电子-空穴等离子体复合发光的受激辐射,同时观察到两种配置下自发辐射谱中存在巨大的差异。通过对实验数据和理论计算结果的分析,初步认为造成了从ZnO薄膜表面和侧面得到的PL谱之间的显著区别原因有两种:一是非对称薄膜波导的吸收损耗造成的波长选择效应,二是薄膜波导对掠出射光的类似薄膜微腔的微腔效应。     

非晶微晶过渡区域硅薄膜的微区喇曼散射研究

通过改变氢气对硅烷气体的稀释程度,并保持其他的沉积参量不变,用等离子体增强化学气相沉积(PECVD)方法成功地制备出处于非晶微晶相变过渡区域的硅薄膜样品.测量了样品的室温光电导和暗电导,样品的光电性能优越,在50mW·cm-2的白光照射下,光电导和暗电导的比值达到106.在室温下用微区喇曼谱研究了薄膜的微结构特性,用高斯函数对喇曼谱进行了拟合分析.结果表明,在我们的样品制备条件下,当H2和SiH4的流量比R较小时,样品表现出典型的非晶硅薄膜的结构特性;随流量比R的增大,薄膜表现出两相结构,其中的微晶成分随 关键词： 非晶硅 薄膜 喇曼散射 微结构     

采用PVA方法制备ZnO基发光稀磁半导体

不同的制备工艺对ZnO薄膜的微结构和性能有很大的影响,为了得到成本较低,样品具有较好特性的实验方法,对于制备手段进行了探索。使用PVA溶胶-凝胶法制备了Zn_0.88Co_0.12O薄膜,研究了不同退火工艺对其微结构的影响。对于Zn_0.88Co_0.12O样品的微结构和室温下的铁磁性和发光特性,具体比较分析了产生原因。对比了Co掺杂和复合Co、Fe掺杂Zn_0.88(Co_0.5Fe_0.5)_0.12O样品的微结构,采用振动样品磁强计(VSM)测量了样品的磁特性,发现单一掺杂的薄膜具有更好的晶体质量和更强的磁性。     

硫酸根离子对草酸-硫酸混合酸中制备的多孔阳极氧化铝光致发光特性的影响

采用电化学阳极氧化法,分别在草酸、硫酸及两者不同浓度比的混合酸中制备了AAO薄膜样品,并分别观察了在250,296 nm光激发下的光致发光(PL)特性。结果表明:草酸和混合酸中制备的AAO薄膜,在250~550 nm范围内的光致发光与不同存在或分布形式的草酸杂质形成的发光中心相关。硫酸根离子对混合酸中制备的AAO薄膜的PL特性有很大影响,随硫酸根离子浓度的增加发光峰位逐渐蓝移。分析了出现上述实验现象的原因。     

氦压对类金刚石薄膜结构和光学性质的影响

使用脉冲激光沉积技术在不同氦压下制备了系列无氢类金刚石薄膜,测量了样品的Raman光谱、光吸收光谱和光致发光光谱,采用原子力显微镜测试了薄膜的表面形貌,研究了薄膜的微结构和光学性质与制备条件的依赖关系. 结果表明,该薄膜是由sp2和sp3杂化碳原子组成的非晶碳膜. 薄膜的光学带隙在1.45～1.78 eV. 薄膜的发光在可见光区呈宽带结构,氦压能够对类金刚石薄膜的结构和光学性质产生较大影响. 当氦压从0.05 Pa升高至15 Pa时,sp2团簇变大,带尾态增多,从而导致薄膜的发光增强,光学带隙变窄,发光峰位红移. AFM 形貌表明随着氦压的升高,薄膜的表面由致密光滑变得粗糙,并且许多大小不均匀的球状颗粒出现在薄膜表面.     

Efficient silicon light emitting diodes made by dislocation engineering

Efficient silicon-based light emitting diodes have been fabricated using the dislocation engineering method. Crucially this technique uses entirely conventional ULSI processes. The devices were fabricated by conventional low-energy boron implantation into silicon substrates followed by high-temperature annealing, and strong silicon band edge luminescence was observed. Dislocation engineering is also shown to reduce the thermal quenching for other material systems. Dislocation engineered β-FeSi₂ and Er light emitting devices were fabricated and room temperature electroluminescence at 1.5 μm was observed in both cases.     

硅基光源的研究进展

随着人们对大容量、高速和低成本的信息传播的要求越来越迫切, 近年来硅基光电子学得以蓬勃发展, 但硅基光源一直没有得到真正的解决, 成为制约硅基光电子学发展的瓶颈. 硅的间接带隙本质给高效硅基光源的实现带来很大困难, 实用化的硅基激光是半导体科学家长期奋斗的目标. 本文分别介绍了硅基发光材料、硅基发光二极管和硅基激光的研究进展, 最后总结了目前各种硅基光源面临的问题和未来的发展方向.     

GaN基发光二极管衬底材料的研究进展

GaN基发光二极管(LED)作为第三代照明器件在近年来发展迅猛.衬底材料作为LED制造的基础,对器件制备与应用具有极其重要的影响.本文分析综述了衬底材料影响LED器件设计与制造的关键特性(晶格结构、热胀系数、热导率、光学透过率、导电性),对比了几种常见衬底材料(蓝宝石、碳化硅、单晶硅、氮化镓、氧化镓)在高质量外延层生长、高性能器件设计和衬底材料制备方面的研究进展,并对几种材料的发展前景做出了展望.     

Effect of excimer laser annealing on the silicon nanocrystals embedded in silicon-rich silicon nitride film

The investigations of silicon-rich silicon nitride film grown by plasma-enhanced chemical vapor deposition and then annealed by excimer laser have been carried out systematically. The surface roughness and the crystallization of the films have significantly been improved after the excimer laser annealing. The samples demonstrate visible photoluminescence emission under optical excitation at room temperature. It is found that the emission peak energy as well as emission intensity changes with laser annealing conditions, and the relevant mechanism is discussed in detail. Our investigation exhibits the size controllability of silicon nanocrystals embedded in the silicon nitride film, which implies promising applications in optoelectronic devices such as light-emitting diodes and solar cells.     

KrF准分子激光退火氢化非晶碳化硅薄膜的晶化研究

介绍了利用KrF准分子脉冲激光对氢化非晶碳化硅(a-SiC∶H)薄膜进行激光退火以实现薄膜的结晶化。利用等离子增强化学气相沉积(PECVD)在单晶Si(100)衬底上制备a-SiC∶H薄膜, 再用不同能量密度的激光对薄膜样品进行退火。分析表明, 选用合适能量密度的激光退火能够实现a-SiC∶H薄膜的结晶化, 且结晶颗粒大小随着入射激光能量密度的增加而增大; 显微图表明当入射能量密度超过200 mJ/cm2时, 薄膜表面出现由热弹性波引起的表面波纹现象, a-SiC∶H薄膜结晶过程为液相结晶; 傅里叶红外谱(FTIR)表明随着入射能量密度增加, 薄膜中氢含量降低, Si-C峰增强并且峰位出现蓝移, 薄膜的结晶度提高。     

Amorphous SiC film formation on Si(100) using electron beam excitation

The effect of electron impact on methylsilane (CH₃SiH₃) conversion to amorphous-Si_0.5C_0.5:H (a-Si_0.5C_0.5:H) films on Si(100) has been studied by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption (TPD), and low energy electron diffraction (LEED). It is found that electron impact greatly enhances CH₃SiH₃ decomposition on Si(100) at both 90 K and 300 K, resulting in a-Si_0.5C_0.5:H thin film formation. Thermal annealing of the film causes hydrogen desorption and amorphous silicon carbide (a-SiC) formation. Upon annealing to temperatures above 1200 K, the a-SiC film became covered by a thin silicon layer as indicated by AES studies. Ordered structures are not produced by annealing the a-SiC up to 1300 K.     

Effect of nanometer sized Ni dot/Ag/Pt reflection metal of InGaN light emitting diodes on conversion efficiency of yellow phosphor

Nanometer sized Ni-dot/Ag/Pt metal coating films with different Ni-dot sizes were incorporated in InGaN based blue light emitting diodes as p-type reflection metal to enhance the extraction efficiency of blue light. For the reflectivity change from 84% to 93.7%, the optical output power of blue light before phosphor coating and the luminous flux of white light after phosphor deposition have improved by 49.3% and 58.2% at 350 mA, respectively. For the presented white light devices, the blue and yellow luminescence respectively has been improved relatively up to 1.52 and 1.67 times. The improved extraction efficiency of yellow light from the phosphor integrated blue light emitting diode is thought to be attributed to the reduction of round trip loss of blue and yellow light inside the device due to the enhanced reflectivity of nanometer sized Ni/Ag/Pt p-type reflection metal.     

包含硅量子点的富硅SiNx 薄膜结构与发光特性

采用等离子体增强化学气相沉积法, 以NH₃与SiH₄为反应气体, n型单晶硅为衬底, 低温(220 ℃)沉积了富硅氮化硅(SiN_x)薄膜. 在N₂氛围中, 于500–1100 ℃ 范围内对样品进行了热退火处理. 采用Raman 光谱技术分析了薄膜内硅量子点的结晶情况, 结果表明, 当退火温度低于950 ℃时, 样品的晶化率低于18%, 而当退火温度升为1100 ℃, 晶化率增加至53%, 说明大部分硅量子点都由非晶态转变为晶态. 实验通过Fourier 变换红外吸收(FTIR)光谱检测了样品中各键的键合结构演变, 发现Si–N键和Si–H键随退火温度升高向高波数方向移动, 说明了薄膜内近化学计量比的氮化硅逐渐形成. 实验还通过光致发光(PL)光谱分析了各样品的发光特性, 发现各样品中均有5个发光峰, 讨论了它们的发光来源, 结合Raman光谱与FTIR光谱表明波长位于500–560 nm的绿光来源于硅量子点, 其他峰则来源于薄膜内的缺陷态. 研究了硅量子点的分布和尺寸对发光带移动的影响, 并根据PL峰位计算了硅量子点的尺寸, 其大小为1.6–3 nm, 具有良好的限域效应. 这些结果有助于制备尺寸不同的硅量子点和基于硅量子点光电器件的实现. 关键词： 硅量子点 氮化硅薄膜 光致发光 Fourier 变换红外吸收     

Optical and physicochemical properties of hydrogenated silicon nitride thin films: Effect of the thermal annealing

The effect of thermal annealing on the optical and physicochemical properties of hydrogenated silicon nitride films was studied. These films were deposited by plasma-enhanced chemical vapor deposition from a mixture of silane, ammonia, and nitrogen. Subsequently, the films were annealed at various temperatures ranging from 400°C to 1000°C. The properties of the films were studied using ellipsometry and Fourier transform infrared spectroscopy. The Maxwell Garnet model considers the silicon nitride material as heterogeneous with three distinct phases: silicon, stoichiometric silicon nitride, and hydrogen. Based on the ellipsometric analysis, the annealing treatment leads to reduce the volume fraction of both hydrogen and silicon. As a result, the stoichiometry parameter significantly increases from 1.24 to 1.32 making it closer to the stoichiometric silicon nitride one. According to the infrared data, a noticeable decrease in the total hydrogen concentration in the films was obtained with respect to the annealing temperature.     

退火及溅射气氛对氮化硅薄膜光致发光的影响

利用射频磁控反应溅射方法制备富硅的氮化硅薄膜。衬底材料为抛光的硅片,靶材为硅靶,在Ar-N₂气环境下,通过改变两种气体的组分比来改变样品成分,并在高纯N₂气氛下对其进行高温退火处理。用X射线光电子能谱(XPS)和X射线衍射(XRD)对样品进行了表征,并测试了样品的光致发光谱 (PL)。实验结果表明：X射线光电子能谱中出现了Si—N键合结构,同时还有少量的Si—O键生成,通过计算得出Si/N比值约为1.51,制备出了富硅的氮化硅薄膜;薄膜未经退火前,在可见光区域没有观察到明显的光致发光峰,经过高温退火后,XRD中新出现的衍射峰证实了纳米硅团簇的生成,PL图谱中在可见光区域出现了光致发光峰的蓝移现象,结合XRD结果,用纳米晶的量子限域效应对上述现象进行了合理解释。