高剂量注氮对注氧隔离硅材料埋氧层中正电荷密度的影响

为研究注氮改性对注氧隔离硅材料中埋氧层性质的影响,向其埋氧层内注入了10¹⁶ cm^-2的高剂量氮.实验结果表明,与未注氮的埋氧层相比,所有注氮的埋氧层中的正电荷密度显著增加.实验还发现,注氮后的退火可使埋氧层内的正电荷密度进一步上升.但与注氮导致的埋氧层内正电荷密度的显著上升相比,退火时间对注氮的埋氧层内正电荷密度的影响不大.电容-电压测量结果显示,在埋氧层内部,注氮后未退火的样品与在1100 ℃的氮气气氛下退火2.5 h的样品相比,二者具有近似相同的等效正电荷 关键词： 注氧隔离 埋氧 注氮 正电荷密度     

基于Si-rich SiNx/N-rich SiNy多层膜结构电致发光特性研究

利用等离子体增强化学气相沉积法制备了富硅氮化硅/富氮氮化硅多层膜,并以此氮化硅基多层膜作为有源层构建电致发光器件,在室温下观察到了较强的电致可见发光.在此基础上,研究多层膜结构中作为势垒层的富氮氮化硅层对器件电致发光性质的影响,实验结果表明通过改变势垒层的Si/N组分,调制其势垒高度,器件的电致发光效率可得到显著地提高.     

基于Si-rich SiNx/N-rich SiNy多层膜结构电致发光特性研究

利用等离子体增强化学气相沉积法制备了富硅氮化硅/富氮氮化硅多层膜,并以此氮化硅基多层膜作为有源层构建电致发光器件,在室温下观察到了较强的电致可见发光.在此基础上,研究多层膜结构中作为势垒层的富氮氮化硅层对器件电致发光性质的影响,实验结果表明通过改变势垒层的Si/N组分,调制其势垒高度,器件的电致发光效率可得到显著地提高. 关键词： 电致发光 多层膜 氮化硅     

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采用蒙特卡罗模型对氮空心阴极放电等离子体鞘层离子(N2 、N )的输运过程进行了模拟研究,计算了阴极鞘层中氮离子(N2 、N )的能量及角分布的空间变化和粒子密度及平均能量随放电参数的变化规律。研究结果表明:空心阴极放电产生的氮离子,在鞘层输运过程中,N2 是密度几乎不变的低能粒子;N 是密度逐渐减少的高能粒子。随着电压增加,N 密度减小,平均能量增加;N2 密度和平均能量变化不明显。能量及入射角的相对分布规律与平板电极氮直流辉光放电基本类似,但圆筒空心阴极放电更有利于氮离子的产生。     

SIMOX SOI埋氧注氮工艺对埋氧中固定正电荷密度的影响

在SIMOX SOI材料的埋氧中注氮是为了增强该类材料的抗辐射能力.通过C-V研究表明，对于埋氧层为150 nm的SIMOX SOI材料来说，当在其埋氧中注入4×10¹⁵cm^-2剂量的氮后，与未注氮埋氧相比，注氮埋氧中的固定正电荷密度显著增加了；而对于埋氧层为375nm的SIMOX SOI材料来说，当注氮剂量分别为2×10¹⁵cm^-2和3×10¹⁵cm^{-2关键词： SIMOX 埋氧 注氮 固定正电荷密度}     

水氨或/和六甲基二硅氮烷表面处理碱催化二氧化硅增透膜结果的对比研究

针对溶胶-凝胶法制备的1/4波长二氧化硅增透膜耐环境性差的缺点,对其进行了水氨或/和六甲基二硅氮烷的表面处理,并对单一气氛处理和两种气氛联合处理后的膜层性质进行了对比研究.展现了膜层经各项表面处理后物理性质和微观结构的变化,以及两种气氛联合处理时因处理顺序不同而引起的最终结果的差异.研究表明:水氨蒸汽处理促进了膜层粒子间表面羟基的交联,膜层较处理前厚度降低,但耐摩擦性增强,光学透过率基本保持不变;硅氮烷蒸汽处理向膜层引入了甲基,膜层极性较低,粒子间作用力因此降低,耐摩擦性下降,但疏水性得到良好的改善;先水氨后硅氮烷蒸汽处理时,水氨蒸汽的前处理在提高膜层耐摩擦的同时降低了表面羟基的数量,使后续硅氮烷处理时强度降低,故两步处理后膜层保持了较好的耐摩擦性和一定的疏水性;而先硅氮烷后水氨蒸汽处理时,硅氮烷蒸汽的前处理明显改善了膜层的疏水性,却因膜层表面羟基减少、间距增大而降低了水氨蒸汽的处理强度,耐摩擦性虽有较大提高,但稍弱于单一水氨蒸汽处理时的耐摩擦性.     

水氨或/和六甲基二硅氮烷表面处理碱催化二氧化硅增透膜结果的对比研究

针对溶胶-凝胶法制备的1/4波长二氧化硅增透膜耐环境性差的缺点,对其进行了水氨或/和六甲基二硅氮烷的表面处理,并对单一气氛处理和两种气氛联合处理后的膜层性质进行了对比研究.展现了膜层经各项表面处理后物理性质和微观结构的变化,以及两种气氛联合处理时因处理顺序不同而引起的最终结果的差异.研究表明:水氨蒸汽处理促进了膜层粒子间表面羟基的交联,膜层较处理前厚度降低,但耐摩擦性增强,光学透过率基本保持不变;硅氮烷蒸汽处理向膜层引入了甲基,膜层极性较低,粒子间作用力因此降低,耐摩擦性下降,但疏水性得到良好的改善;先水氨后硅氮烷蒸汽处理时,水氨蒸汽的前处理在提高膜层耐摩擦的同时降低了表面羟基的数量,使后续硅氮烷处理时强度降低,故两步处理后膜层保持了较好的耐摩擦性和一定的疏水性;而先硅氮烷后水氨蒸汽处理时,硅氮烷蒸汽的前处理明显改善了膜层的疏水性,却因膜层表面羟基减少、间距增大而降低了水氨蒸汽的处理强度,耐摩擦性虽有较大提高,但稍弱于单一水氨蒸汽处理时的耐摩擦性.     

X光激发氮氧化铝膜层电子特征能量探测与分析

本文报告了用Ｘ光电子能谱法（ＸＰＳ）对氮氧化铝／铁膜内层电子特征能量的探测与分析,获得了膜层中不同深度的元素成分及化学结构．结果表明：ＸＰＳ方法是研究氮氧化铝选择性吸收膜的有效方法．     

X光激发氮氧化铝膜层电子特征能量探测与分析

本文报告了用Ｘ光电子能谱法（ＸＰＳ）对氮氧化铝／铁膜内层电子特征能量的探测与分析,获得了膜层中不同深度的元素成分及化学结构,结果表明：ＸＰＳ方法是研究氮氧化铝选择性吸收膜的有效方法 。     

不同施氮水平下玉米冠层光谱反射特征分析

通过田间试验研究了玉米不同生长期冠层光谱反射率的变化特征,分析了不同施氮水平下可见光区冠层光谱反射率的差异。研究结果表明：受作物群体光和能力的影响,玉米可见光区冠层反射光谱在拔节期达最高点,随后持续降低; 近红外区,苗期反射率最低,在拔节期达最高点,喇叭口期有所降低而在开花吐丝期得到回升,进入灌浆期后又下降。不同施氮水平下,拔节期随施氮水平的增加,叶绿素的强吸收带(430～450和640～660 nm)玉米冠层反射曲线呈下降排列,但在550 nm附近反射率R_正常>R_偏低>R_偏高; 喇叭口期偏低施氮区的冠层反射率在可见光区明显高于其它施氮水平,且偏高和正常施氮区域内光谱反射强度基本相同,显示过量施肥并不会促进作物生长。分析玉米生长期间不同施氮水平下光谱反射率的差异,对监测玉米生长状况,指导田间施肥具有重要的现实意义。     

Characterization of ZnO:Ga and ZnO:N films prepared by PLD

The thin films of zinc oxide have been produced by the pulse laser deposition method at various levels of gallium and nitrogen doping. To obtain the n-type films we used gallium doping with concentration of gallium from zero up to 5 at %. The dependence of photoluminescence of the epitaxial ZnO:Ga films on the concentration of gallium doping has been studied. An optimum range of the n-type ZnO films doping with gallium has been determined to obtain highly effective films from the viewpoint of realizing p-n transitions. This range, on the one hand, defines the maximal PL amplitude and, on the other hand, specifies the minimal specific resistance that corresponds to an interval of 0.125–1.000 at % Ga. To produce the p-type ZnO:(Ga, N) films, the ZnO targets with the content of GaN from zero up to 2 at % were used. N₂O was used as a buffer gas. A difference is observed in the positions of the peaks of the emission lines of the photoluminescence spectra for the ZnO films, doped with gallium (Ga) and co-doped with gallium and nitrogen (N).     

MOVPE growth study of BxGa(1−x)N on GaN template substrate

BGaN materials with good structural quality and surface morphology have been successfully grown on GaN template substrates by low pressure metal organic vapour phase epitaxy. TEB and NH3 were used as precursors of boron and nitrogen respectively. All the growths were performed under 100% N₂ process gas. Boron concentration was estimated by HRXD measurements combined with SIMS analysis. Single-crystal layers of BGaN with B content as high as 3.6% have been obtained.     

Wetting and reactive thin film growth

The wetting process of the GaN(0 0 0 1) surface by Ga is studied in situ in real time by low energy electron microscopy and diffraction. The reversibility of the phase transitions in the wetting layer is examined in detail and the consequences for the growth of GaN layers by reaction with ammonia and activated nitrogen are discussed. It is concluded that the growth of smooth (0 0 0 1)-terminated GaN layers may be considered as quasi-liquid phase epitaxy.     

Columnar Structures and Stress Relaxation in Thick GaN Films Grown on Sapphire by HVPE

Thick GaN films with high quality are directly grown on sapphire in a home-built vertical hydride vapour phase epitaxy （HVPE） reactor. The optical and structural properties of large scale columnar domains near the interface are studied using cathodoluminescence and micro-Raman scattering. These columnar domains show a strong emission intensity due to extremely high free carrier concentration up to 2 × 10^19 cm^-3, which are related with impurities trapped in structural defects. The compressive stress in GaN film clearly decreases with increasing distance from interface. The quasi-continuous columnar domains play an important role in the stress relaxation for the upper high quality layer.     

极化诱导实现AlGaN薄膜材料中的超高电子浓度(1020cm-3)掺杂

材料的载流子浓度和迁移率是影响器件性能的关键因素, 变温Hall测试结果证明杂质掺杂AlGaN中的载流子浓度和迁移率随温度 降低而减小.然而极化诱导掺杂的载流子浓度和迁移率不受温度变化的影响.以准绝缘 的GaN体材料作为衬底, 在组分分层渐变的AlGaN中实现的极化诱导掺杂浓度 仅仅在10¹⁷ cm^-3数量级甚至更低. 本研究采用载流子浓度为10¹⁶ cm^-3量级的非有意n型掺杂GaN模板为衬底, 用极化诱导掺杂技术在分子束外延生长的AlGaN薄膜材料中实现了高 达10²⁰ cm^-3 量级的超高电子浓度. 准绝缘的体材GaN半导体作衬底时, 只有表面自由电子作为极化掺杂源, 而非有意掺杂的GaN模板衬底除了提供表面自由电子外,还能为极化电场 提供更多的自由电子"源", 从而实现超高载流子浓度的n型掺杂.     

Si基GaN外延层光致发光光谱与二次离子质谱的研究

报道了在Si基上用简便的真空反应法制备出GaN外延层．光致发光光谱测试结果表明不同的生长温度和退火工艺会对GaN外延层的发光特性产生影响,在1050℃下生长的GaN外延层的发光强度高于其他温度下生长的发光强度,退火可以使GaN外延层的发光强度增强．二次离子质谱(SIMS)测试结果表明外延层中Ga和N分布均匀,在表面处Ga发生了偏聚,同时外延层中还存在Si,O等杂质,这使得外延层中背景电子浓度高达1.7×10¹⁸/cm³. SIMS测试结果还表明,在外延生长前采用 关键词：     

Gallium nitride nanoparticle synthesis using nonthermal plasma with gallium vapor

Gallium nitride (GaN) nanoparticles are synthesized by the gallium particle trapping effect in a N₂ nonthermal plasma with metallic Ga vapor. A proposed method has an advantage of synthesized GaN nanoparticle purity because the gallium vapor from the inductively heated tungsten boat does not contain any impurity source. The synthesized particle size can be controlled by the amount of Ga vapor, which is adjusted using the plasma emission ratio of nitrogen to gallium, owing to the particle trapping effect. The synthesized nanoparticles are investigated by electron microscopy studies. High-resolution transmission electron microscopy (HRTEM) studies confirm that the synthesized GaN nanoparticles (10–40 nm) crystallize in a single-phase wurtzite structure. Room-temperature photoluminescence (PL) measurements indicate the band-edge emission of GaN at around 378 nm without yellow emission, which implies that the synthesized GaN nanoparticles have high crystallinity.     

A new route for the synthesis of nitrides: The solvothermal preparation of GaN

Abstract

A new solvothermal route for the synthesis of nitrides is proposed using liquid NH3 as solvent in supercritical conditions, Such a preparation method was applied to the synthesis of GaN using gallium metal as starting material.

GaN is a wide band-gap semi-conductor (3.4eV). It is a very attractive nitride due to its various applications in micro- and opto-electronics [1,2]. Consequently, many research groups are interested in synthesising GaN. Two methods have been principally developed:

(i) synthesis of thin films by epitaxy [3,4]

(ii) synthesis of bulk GaN by high pressure method [5,6].

The new proposed process leads to fine microcrystallites of GaN with the wurtzite-type structure. The chemical purity can be optimised versus the synthesis mechanism. The size and shape of the crystallites would be influenced by the nature of the nitriding additive and the thermodynamical conditions (pressure and temperature) used for the synthesis.     

AlN/蓝宝石模板上生长的GaN研究

研究了在分子束外延制备的AlN/蓝宝石模板上采用金属有机物化学气相外延生长的非故意掺杂GaN的材料性质.采用X射线衍射(XRD)、透射电镜(TEM)和原子力显微镜研究了AlN模板的晶体质量和表面相貌对GaN的影响.结果表明,当AlN的表面粗糙度较小时,尽管AlN模板的位错密度较高((102)面XRD ω扫描半高全宽900—1500 arcsec),但生长得到的GaN依然具有和在蓝宝石衬底上采用"二步法"生长的GaN可比拟的晶体质量((002)面XRD ω扫描半高全宽200—30 关键词： 氮化镓 氮化铝 金属有机物化学气相外延     

GaN中与C和O有关的杂质能级第一性原理计算

用局域密度泛函线性丸盒轨道大型超原胞方法(32个原子),对纯纤锌矿结构的GaN用调节计算参数(如原子球与“空球”的占空比)在自洽条件下使Eg的计算值(323eV)接近实验值(35eV).然后以原子替代方式自洽计算杂质能级在Eg中的相对位置.模拟计算了六角结构GaN中自然缺陷以及与C和O有关的杂质能级位置,包括其复合物.计算结果表明,单个缺陷如镓空位VGa、氮空位VN、氧代替氮ON、炭代替氮CN、炭代替镓CGa等与已有的计算结果基本一致.计算结果表明杂质复合物会导致单个杂质能级位置的相对变化.计算了CNON,CGaCN,CNOV和CGaVGa,其中CNON分别具有深受主与浅施主的特征,是导致GaN黄光的一种可能的结构. 关键词： GaN 杂质能级 电子结构