用脉冲激光沉积方法制备氮化铝薄膜

介绍了用脉冲激光沉积 (PLD)方法制备AlN薄膜的工作 ,在Si(10 0 )衬底上得到了光滑平整、透明度高的AlN薄膜 ,由实验结果拟合得到能隙宽度为 5 7eV。考察了衬底温度和退火温度的影响。     

液体中激光熔蚀固体靶制备氮化碳纳米晶

本文提出一种独特的激光熔蚀法即在液体中激光熔蚀固体靶制备纳米晶，并且首次在氨水中激光熔蚀石墨靶制备出氮化碳纳米晶。透射电镜（ＴＥＭ）和高分辨率电镜（ＨＲＥＭ）分析表明制备的氮化碳纳米晶由α－Ｃ３Ｎ４、β－Ｃ３Ｎ４和Ｇｒａｐｈｉｔｅ－Ｃ３Ｎ４晶粒组成。     

CO_2激光辅助等离子体激励式化学气相沉积非晶形低氢氮化硅薄膜

利用CO2 激光辅助等离子体激励式化学气相沉积系统 (Laser assistedPlasma enhancedChemicalVaporDeposition ,orLAPECVD) ,在硅 (Si)基片上沉积出非晶形含氢较低的氮化硅 (a∶Si Nx∶H)薄膜。这些薄膜的折射率增加、膜致密性及平整度良好 ,其抗腐蚀性亦明显提升。LAPECVD沉积法是在电容式RF放电解离反应气体的同时 ,以输出功率密度 3 3W cm2 的CO2 激光斜向照射在硅基片上。因为激光斜照在硅基片上所提升的温度只有 5 5℃ ,且可大量减少膜中的氢含量 ,以波长 10 5 8μm激光照射获得的薄膜品质较波长 9 5 2 μm更佳 ,将此一非热效应的发生原因提出推论     

氮化硅/石墨激光合金化涂层的组织结构与性能研究

为获得金属表面特别是高副接触金属表面含自润滑特性且具有高硬度耐磨特性的功能材料 ,研究了 45 # 钢表面激光合金化氮化硅 /石墨复合涂层的工艺方法、组织特征、界面形态及其形成机制 ,利用光学显微镜、扫描电镜和X射线能谱对所形成合金化层的元素分布和含量进行了分析 ,并对试样硬度进行了测定。结果表明 ,合金化层中元素Fe ,Co ,Si,C分布均匀 ;C含量达到了 15 6 9%,大部分以石墨的形式存在 ,具有一定的自润滑性能 ;但在形成合金化层的温度条件下 ,氮化硅分解严重 ;合金化层硬度提高的主要原因是Si Fe ,Co Fe固溶体的强化作用及高碳马氏体的生成和高硬度碳化物的存在。     

Theoretical approach to estimate laser process parameters for drilling in crystalline silicon

This paper presents a simple method for estimating the ablation rate during drilling processes in crystalline silicon wafers. Using data from literature, the physical process of material heating, melting, and ejection can be estimated on a time scale and leads to a temporal separation of the pulse duration in two parts. The latter one offers a theoretical determination of the expected average ablation rate. The results of this approximation coincide with experimental values and offer solutions to increase drilling efficiency. The experiments were done with a q‐switched solid‐state laser emitting at 1064 nm wavelength at pulse durations between 810 ns and 1440 ns. Copyright © 2010 John Wiley & Sons, Ltd.     

LIVCD法制备纳米氮化硅粉末工艺参数对粉体特征影响的研究

激光诱导气相沉积法是制备纳米氮化硅粉末的主要方法之一。在制备纳米粉体过程中,各工艺参数的变化对粉体特征有很大的影响。在激光制Si3N4纳米粉中基本的运行参数有:激光强度(I),反应池压力(P),反应火焰温度(T),反应气体配比(ΦSiH4／ΦNH3),反应气体流速(V)等。通过实验研究了各个工艺参数对粉体特征的影响并分析了其影响的原因。     

高效单晶硅PERC局部背表面场及接触的优化

钝化发射极和背面电池(PERC)技术可有效提高电池效率,在常规p型电池的背面增加了钝化层,并形成了局部背表面场(LBSF)结构.介绍了PERC结构电池的工艺流程,分析了背场(BSF)的形成机制,主要研究了PERC的LBSF制备工艺及影响要素.通过采用激光消融后清洗方法改善了背表面形貌,平整的背表面形貌有利于BSF的形成.通过优化烧结条件,电池的填充因子得到改善.讨论了激光开槽图形对开路电压以及填充因子的影响.测试结果表明,PERC转换效率绝对值提升了0.9％,达到20.83％,填充因子达到80.7％.     

长脉宽激光切割聚晶立方氮化硼工艺研究

为了获得聚晶立方氮化硼（PCBN）最优的激光切割质量和切割效率,依据烧蚀直径和入射激光脉冲能量的函数关系,得出PCBN烧蚀阈值为1.796J/cm2。采用Nd:YAG激光器对型号为BN250的PCBN进行切割试验,分析了切割速率、激光功率以及脉冲频率对切割质量的影响规律。通过切缝的显微观测对比,总结出不同激光工艺参量下PCBN缝宽的变化趋势。结果表明,对于脉宽为100μs的激光,当激光功率为28W、脉冲频率为60Hz、切割速率为20mm/min时,能够获得PCBN激光切割的最优切缝和较高的切割效率。该工艺方法和数据的建立,对今后PCBN或其它超硬材料的激光加工有着重要参考价值。     

氮化硅的选区激光烧结成型研究

应用陶瓷粉末的选区激光烧结(SLS)成型原理,以氮化硅(Si3N4)和环氧树脂(EP)为材料,采用机械混合的方法制备SLS用Si3N4陶瓷粉末,测试其流动性和松装密度,进行选区激光烧结实验并制备试件。采用扫描电子显微镜观察烧结件的微观形貌,测试其三点抗弯强度。结果表明,优化Si3N4和EP粉末的粒径级配可有效增大铺粉密度、烧结件的致密度和强度。粉末粒径接近单层厚度时烧结件易发生移动和翘曲,粒径＜40 μm时,粉末易于粘附铺粉辊。     

高能纳秒激光烧蚀单晶硅的微观结构

高能纳秒激光烧蚀硅时,往往会伴随着相爆炸过程,它决定了烧蚀的形貌特征。基于相爆炸的物理过程,分析了相应的烧蚀形貌：相爆炸的发生会使得硅材料发生大范围的去除,高温熔化材料的混合物向外喷溅,冷却形成放射状的冷却条,期间分布着冷却的球状微粒;超热液体的去除部位形成一个类似花瓣状坑,在坑中由于入射光与散射光的干涉形成条纹,其周期与激光光波相似。     

Hydrogen concentration profiles and chemical bonding in silicon nitride

The complementary techniques of nuclear reaction analysis and infrared absorption were used to study the concentration profiles and chemical bonding of hydrogen in silicon nitride for different preparation and annealing conditions. Silicon nitride prepared by chemical vapor deposition from ammonia-silane mixtures is shown to have hydrogen concentrations of 8.1 and 6.5 at.% for deposition temperatures of 750 and 900‡C, respectively. Plasma deposition at 300‡C from these gases result in hydrogen concentrations of ~22 at.%. Comparison of nuclear reaction analysis and infrared absorption measurements after isothermal annealing shows that all of the hydrogen retained in the films remains bonded to either silicon or nitrogen and that hydrogen release from the material on annealing is governed by various trap energies involving at least one Si-H and two N-H traps. Reasonable estimates of the hydrogen release rates can be made from the effective diffusion coefficient obtained from measurements of the spreading of the implanted hydrogen distribution upon annealing. This article sponsored by the U. S. Department of Energy under Contract AT(29-1)-789.     

硅基纳米微粒的激光烧蚀沉积及可见光发射特性

简要介绍了激光烧蚀沉积硅基纳米微粒的基本方法、沉积原理及其可见光发射特性等 ,并对其发展前景作了初步展望。     

Low-Temperature deposition of dielectric films by microwave plasma enhanced decomposition of hexamethyldisilazane

Hexamethyldisilazane (HMDS) has been used as an organosilicon source for the deposition of dielectric films at low temperatures (200-250° C) by microwave plasma enhanced CVD technique. Hydrogenated films of variable composition of silicon carbonitride, silicon oxynitride and silicon dioxide have been deposited by decomposition of HMDS in the presence of additive gases like NH₃, O₂ and H₂ under different process conditions. Deposited films have been characterized by the measurement of refractive index and buffered HF etch rate, and by the analysis of XPS and infrared transmission spectra. An increase in HMDS partial pressure generally results in the decrease of refractive index. The films show stable C-V characteristics of metal-insulator-semicon-ductor (MIS) capacitors with positive insulator charge density.     

CO2 detection with CNx thin films deposited on porous silicon

In recent years, porous silicon (PSi) has attracted a great deal of attention for sensing applications. However, the high reactivity of PSi surfaces causes serious problems of stability. In this work, we developed new thin films that can serve as stabilizer of PSi for CO₂ gas sensors development. PSi surface was coated with carbon nitride (CN_x) film which is one of the most important interfering to stabilize the PSi layer. CN_x film was deposited by pulsed laser ablation. The effect of CO₂ gas on the sensor response was investigated for different polarization voltages. The electrical properties of (Al/CN_x/PSi/Si) structure were modified in the presence of the gas. The device shows a high sensitivity against CO₂ gas. Furthermore, the current variation of the sensor as a function of time has been investigated. The results show that the Al/CN_x/PSi/Si structure becomes stable after the first two weeks.     

激光诱导六甲基乙硅胺烷制备氮化硅纳米粉体

针对激光气相合成氮化硅纳米粉体的性能与成本的矛盾,在对激光合成反应物的研究与分析的基础上,选择廉价、无氯硫、对CO2激光有强吸收、易于处理的有机硅烷反应物六甲基乙硅胺烷(HMDS)作为价格昂贵、难以处理的硅烷(SiH4)的替代反应物,进行了激光合成氮化硅纳米粉体的研究。