金属有机化学气相沉积的研究进展

概述了金属有机化学气相沉积技术(MOCVD)的一般原理,讨论了适用于金属有机化学气相沉积的前驱体化合物及反应器类型,介绍了金属有机化学气相沉积技术在半导体化合物材料和各种薄膜材料中的发展及应用。     

镍的金属有机化学气相沉积

介绍了用MOCVD技术沉积镍膜的应用状况，以及几种典型前驱体的沉积性能，着重介绍了羰基镍的沉积特性。结合MOCVD技术的最新进展，对镍的化学气相沉积技术了简要的展望。     

金属有机化学气相沉积制备铁电薄膜材料研究进展

铁电薄膜是一类重要的功能材料,是近年来高新技术研究的前沿和热点之一.金属有机化学气相沉积(MOCVD)是制备铁电薄膜的一种重要方法.综述了金属有机化学气相沉积法制备铁电薄膜的历史、原理、工艺参数、特点和采用此方法制备出的某些材料的铁电性能.     

用于制备ZnO薄膜的金属有机化学气相沉积设备的研制

介绍了一种制备ZnO薄膜的金属有机化学气相沉积(MOCVD)设备,制备的ZnO薄膜主要用作太阳能电池的背反射电极。该设备的极限压力可达5×10-5 Pa,膜厚均匀性偏差在5%以内,薄膜电阻率约为10-2Ω.cm。本文叙述了设备的用途,技术性能,工作过程和结构特点。并对ZnO薄膜的电阻率与参加反应的水蒸汽流量的关系进行了简单介绍。     

光加热低压金属有机化学气相淀积生长AlGaN

采用光加热低压金属有机化学气相淀积方法成功地制备出高质量的,组分均匀的AlGaN外延层,结果表明,铝和镓的并入效率基本相等,这有别于其他研究报道,此外,建立了铝相对镓的并入效率与气相预反应之间的关系模型,它表明,光加热对预反应有较大的影响,结合GaN的生长可以看出,光加热有利于抑制预反应,从而有利于提高样品质量和铝组分的均匀性。     

微波等离子体化学气相沉积法生长取向性纳米氮化铝薄膜

采用微波等离子增强的化学气相沉积法，在Ｓｉ（１１１）衬底上生长了（００２）选优取向良好的Ａ１Ｎ纳米薄膜。研究沉积参数对膜的形貌、物相结构和生长速率的影响，发现在一定条件下，该沉积过程属于典型的输运控制过程，采用表面吸附生长模型讨论了膜的生长机制。     

金属有机物化学气相沉积法沉积镍膜的影响因素

为了获得高速沉积镍膜的工艺参数，以羰基镍[Ni(CO)4]为前驱体，用金属有机物化学气相沉积法进行试验，以SEM，DSC，XRD测试分析技术探讨了载气、温度和羰基镍的摩尔分数对沉积速率的影响；也探讨了温度及羰基镍的摩尔分数对镍膜微观形貌的影响。结果表明，以氩气为载气比氦气为载气更容易获得高沉积速率；在沉积温度为150℃左右可获得沉积速率较快、微观形貌较好的薄膜；随羰基镍摩尔分数的增加，沉积速率也明显增大，同时薄膜的微观形貌也变得较为粗大，但达到30％之后，沉积速率增速减缓。     

MOCVD方法在Si衬底上低温生长ZnO薄膜

采用二乙基锌(DEZn)和氧化亚氮(N2O)作为锌源和氧源,在低温300℃,利用金属有机化学气相沉积(MOCVD)的方法在Si(100)衬底上制备了ZnO薄膜.通过优化氧锌比,ZnO薄膜为高度单一c轴方向生长.由光致发光谱和反射谱得知,ZnO薄膜的紫外发光峰位于388nm,具有很好的光透性,且其PL谱半峰宽为80meV.     

物理气相沉积薄膜的界面与附着力

近十多年来,气相沉积技术发展十分迅速,无论在理论研究还是应用研究上都取得了丰硕的成果,尤其在PVD薄膜的附着力方面,研究十分活跃。本文根据有限的资料,初步归纳出在PVD过程中,膜/基附着力与基体表面活性密切相关;薄膜与基体之间也可以化学吸附形式结合,形成界面化合物;也可借助离子的轰击作用形成结合良好的扩散过渡层;膜/基界面之间不匹配将使附着力下降,可通过设置过渡层(梯度层)的方式加以解决。     

Al预沉积层对金属有机物化学气相沉积方法在Si衬底上生长AlN缓冲层和GaN外延层的影响

采用金属有机物化学气相沉积法(MOCVD)在硅(Si)衬底制备铝/氮化铝/氮化镓(Al/AlN/GaN)多层薄膜,使用光学显微镜(OM)、原子力显微镜(AFM)、X射线衍射(XRD)等手段表征AlN和GaN薄膜的微观结构和晶体质量,研究了TMAl流量对AlN薄膜和GaN薄膜的形核和生长机制的影响。结果表明,预沉积Al层能促进AlN的形核和生长,进而提高GaN外延层的薄膜质量。TMAl流量太低则预沉积Al层不充分,AlN缓冲层的质量取决于由形核长大的高结晶度AlN薄膜与在气氛中团聚长大并沉积的低结晶度AlN薄膜之间的竞争,AlN薄膜的质量随着TMAl流量的升高而提高,GaN薄膜的质量也随之提高。TMAl流量太高则预沉积Al层过厚,AlN缓冲层的质量取决于由形核长大的高结晶度AlN薄膜与Al-Si回融蚀刻之间的竞争,AlN薄膜的质量随着TMAl流量的升高而降低,GaN薄膜的质量也随之降低。     

基于有限体积法的MOCVD系统反应室的设计

金属有机化合物化学气相沉积(MOCVD)系统是制备GaN等半导体薄膜材料和激光器、LED等光电子器件的主要手段,制备出的材料和器件的品质直接依赖于MOCVD系统。本文基于有限体积法,利用商业软件Fluent对自行设计的一种MOCVD反应室内的温度分布和流场进行数值模拟。希望通过对模拟流场品质的细致分析,对MOCVD反应室的设计和优化起到指导与参考作用。     

用于高质量InGaN/GaN MQWs制备的MOCVD配气系统

本文提出了一种新型的MOCVD恒流配气系统，该配气系统可有效地稳定控制温度和压力等关键工艺条件，在多层复杂结构的生长中改善材料质量。本文给出了该配气系统同传统配气方式生长效果的比较，PL对比测试结果表明，该配气系统在多量子阱结构的制备中具有良好的效果。     

窄流道式MOCVD制备YGBCO超导层研究

金属有机化学气相沉积能连续、快速的沉积高温超导带材YBa₂Cu₃O_7-x (YBCO) 超导层。但金属有机源的利用率与薄膜沉积速率以及沉积一致性难以兼顾, 制备YBCO高温超导带材的成本居高不下。本文提出了一种新的窄流道式反应室以改进薄膜沉积的一致性。在200 mm长度腔体中沉积的280 nm厚的Y_0.5Gd_0.5Ba₂Cu₃O_7-x薄膜J_c分布在3.2~3.5 MA/cm² (77 K, 0 T), 面外、面内半高宽值分别在1.39°~1.49°和1.88°~2.13°, 表面平整致密。YBCO薄膜良好的一致性表明该窄流道反应室对制备YBa₂Cu₃O_7-x超导带材有好的实用性。     

定向金属氮化法制备AlN/Al陶瓷基复合材料研究进展

介绍了氮化铝的结构和性能,并回顾了国内外采用定向金属氮化法制备AlN/Al陶瓷基复合材料的研究成果,详细探讨了合金成分和预形体对AlN/Al陶瓷基复合材料显微结构和生长的影响.指出工艺和显微结构优化、新型复合材料开发是定向金属氮化法制备AlN陶瓷材料的发展方向.     

Metal Organic Chemical Vapour Deposited Thin Films of Cobalt Oxide Prepared via Cobalt Acetylacetonate

The single solid source precursor, cobalt (Ⅱ) acetylacetonate was prepared and characterized by infrared spec-troscopy. Thin films of cobalt oxide were deposited on soda lime glass substrates through the pyrolysis (metal organic chemical vapour deposition (MOCVD)) of single solid source precursor, cobalt acetylaceto-nate, Co[C5H7O2]2 at a temperature of 420℃. The compositional characterization carried out by rutherford backscattering spectroscopy and X-ray diffraction (XRD), showed that the films have a stoichiometry of Co2O3 and an average thickness of 227±0.2 nm. A direct energy gap of 2.15±0.01 eV was calculated by the data obtained by optical absorption spectroscopy. The morphology of the films obtained by scanning electron mi-croscopy, showed that the grains were continuous and uniformly distributed at various magnifications, while the average grain size was less than 1 micron for the deposited thin films of cobalt oxide.     

Co3O4 protective coatings prepared by Pulsed Injection Metal Organic Chemical Vapour Deposition

Cobalt oxide films were grown by Pulsed Injection Metal Organic Chemical Vapour Deposition (PI-MOCVD) using Co(acac)₃ (acac=acetylacetonate) precursor dissolved in toluene. The structure, morphology and growth rate of the layers deposited on silicon substrates were studied as a function of deposition temperature. Pure Co₃O₄ spinel structure was found for deposition temperatures ranging from 360 to 540 °C. The optimum experimental parameters to prepare dense layers with a high growth rate were determined and used to prepare corrosion protective coatings for Fe-22Cr metallic interconnects, to be used in Intermediate Temperature Solid Oxide Fuel Cells.     

Determination of two-dimensional electron and hole gas carriers in AlGaN/GaN/AlN heterostructures grown by Metal Organic Chemical Vapor Deposition

Resistivity and Hall effect measurements on nominally undoped Al_0.25Ga_0.75N/GaN/AlN heterostructures grown on sapphire substrates prepared by metal organic chemical vapor deposition have been carried out as a function of temperature (20-300 K) and magnetic field (0-1.4 T). Variable magnetic field Hall data have been analyzed using the improved quantitative mobility spectrum analysis technique. The mobility and density of the two-dimensional electron gas at the AlGaN/GaN interface and the two-dimensional hole gas at the GaN/AlN interface are separated by quantitative mobility spectrum analysis. The analysis shows that two-channel conduction is present in nominally undoped Al_0.25Ga_0.75N/GaN/AlN heterostructures grown on sapphire substrate.     

Deposition of GaN films on (1 1 1) Si substrates by alternate supply of TMG and NH3

GaN films were grown on (1 1 1) Si substrates at 1000 °C by separate admittances of trimethylgallium (TMG) and ammonia (NH₃). To achieve high quality GaN films, the optimization in growth temperature and layer thickness of AlN buffer layer between GaN film and Si substrate is required. Cross-sectional transmission electron microscopic observations of the GaN/(1 1 1)Si samples show a nearly parallel orientation relationship between the (0 0 0 1) planes of GaN film and the (1 1 1) planes of Si substrate. Room temperature photoluminescence spectra of high quality GaN films show a strong near band edge emission and a weak yellow luminescence. The achievement of high quality GaN films on (1 1 1) Si substrates is believed to be attributed to enhancement in surface mobilities of the adsorbed surface species and adequate accommodation of lattice mismatch between high temperature AlN buffer layer and Si substrate.     

Growth of GaN on SiC/Si substrates using AlN buffer layer by hot-mesh CVD

GaN films were grown on SiC/Si (111) substrates by hot-mesh chemical vapor deposition (CVD) using ammonia (NH₃) and trimetylgallium (TMG) under low V/III source gas ratio (NH₃/TMG = 80). The SiC layer was grown by a carbonization process on the Si substrates using propane (C₃H₈). The AlN layer was deposited as a buffer layer using NH₃ and trimetylaluminum (TMA). GaN films were formed and grown by the reaction between NH_x radicals, generated on a tungsten hot mesh, and the TMG molecules. The GaN films with the AlN buffer layer showed better crystallinity and stronger near-band-edge emission compared to those without the AlN layer.