BC2N薄膜的柱状生长及生长机理

应用热丝辅助等离子体化学气相沉积法(CVD)合成了表面呈柱状的BC₂N薄膜,X射线、红外及X射线电子能谱分析表明,薄膜的化学组分主要为BC₂N,B,C和N原子间互相结合成键.扫描电镜观察到,薄膜表面形貌呈排列整齐、取向一致的柱体,并且发现这种生长方式与沉积参数密切相关.最后从结合能方面讨论了柱状BC₂N的生长机理. 关键词： 2N')" href="#">BC₂N 柱状生长 CVD法     

等离子增强原子层沉积低温生长GaN薄膜

采用等离子增强原子层沉积技术在低温下于单晶硅衬底上成功生长了Ga N多晶薄膜,利用椭圆偏振仪、低角度掠入射X射线衍射仪、X射线光电子能谱仪对薄膜样品的生长速率、晶体结构及薄膜成分进行了表征和分析.结果表明,等离子增强原子层沉积技术生长Ga N的温度窗口为210—270?C,薄膜在较高生长温度下呈多晶态,在较低温度下呈非晶态;薄膜中N元素与大部分Ga元素结合成N—Ga键生成Ga N,有少量的Ga元素以Ga—O键存在,多晶Ga N薄膜含有少量非晶态Ga_2O_3.     

微晶硅薄膜的表面粗糙度及其生长机制的X射线掠角反射研究

采用等离子体增强化学气相沉积技术沉积一系列处于不同生长阶段的微晶硅薄膜.通过同步辐射X射线掠角反射技术研究微晶硅薄膜的表面粗糙度随时间等的演化，探讨微晶硅薄膜的生长动力学过程及其生长机制.研究结果表明，在衬底温度为200 ℃，电极间距为2 cm，沉积气压为6.66×1０² Pa，射频功率密度为0.22 W/cm²，氢稀释度分别为99%和98%的沉积条件下，在玻璃衬底上生长的微晶硅薄膜生长指数β分别为0.21±0.01和0.24±0.01.根据KPZ模型，微晶硅薄膜的生长机制为有限扩散生长. 关键词： X射线掠角反射 微晶硅薄膜 表面粗糙度 生长机制     

等离子增强原子层沉积低温生长AlN薄膜

采用等离子增强原子层沉积技术在单晶硅基体上成功制备了AlN晶态薄膜, 利用椭圆偏振仪、原子力显微镜、小角掠射X射线衍射仪、高分辨透射电子显微镜、 X射线光电子能谱仪对样品的生长速率、表面形貌、晶体结构、薄膜成分进行了表征和分析, 结果表明, 采用等离子增强原子层沉积制备AlN晶态薄膜的最低温度为200 ℃, 薄膜表面平整光滑, 具有六方纤锌矿结构与(100)择优取向, Al_2p与N_1S的特征峰分别为74.1 eV与397.0 eV, 薄膜中Al元素与N元素以Al-N键相结合, 且成分均匀性良好. 关键词： 氮化铝 等离子增强原子层沉积 低温生长 晶态薄膜     

ZnO薄膜的自组织设计及形貌控制

采用单源化学气相沉积(SSCVD)法,在Si(100)基片上通过改变前驱反应体与基片的入射角度,获得了可控柱状取向的ZnO薄膜.研究发现,入射角度的改变可使沉积薄膜中的柱状结构的生成方向倾斜.但X射线衍射(XRD)分析表明:ZnO薄膜的c轴(002)取向与入射角无关,且不沿ZnO柱状结构的生长方向取向.由于ZnO的(002)面为其表面自由能最低且原子密度高的晶面,ZnO薄膜的生长更易于在垂直于基片表面的方向c轴取向生长.     

΢�����ӻ�������������廯ѧ����������Ʊ��ྦྷ�象Ĥ

利用微波电子回旋共振等离子体增强型化学气相沉积(ECR-PECVD)采用一步法直接在K9玻璃上低温沉积制备了多晶硅薄膜.研究了不同实验参数对薄膜沉积的影响,采用X射线衍射(XRD)、拉曼光谱、扫描电子显微镜(SEM)等实验分析方法对不同条件下制备的样品进行了晶体结构和表面形貌分析,并讨论了多晶硅薄膜沉积的最佳条件.实验结果表明,玻璃衬底上多晶硅薄膜呈柱状生长,并有一定厚度的非晶孵化层;较高氢气比例和衬底温度有利于结晶,薄膜的结晶率达到了62％;晶粒团簇的最大尺寸约为500nm.     

直流磁控溅射氮化铁薄膜生长的动力学标度

利用直流磁控溅射方法,以Ar/N2作为放电气体,通过改变放电气体中N2的流量(N2流量比分别为5%,10%,30%,50%)及溅射时间(160,30,20,10,5min),在玻璃衬底上沉积了FexN薄膜。用X射线光电子能谱(XPS)方法确定了不同N2流量下薄膜的成分;X射线衍射(XRD)方法分析了不同N2流量下的FexN薄膜结构,当N2流量比为5%时获得了FeN0 056相,10%时为ε Fe3N相,30%和50%流量比下均得到FeN相。利用原子力显微镜(AFM)和掠入射X射线散射(GIXA)方法研究了膜表面的粗糙度和形貌,发现随着N2流量的增加,薄膜表面光滑度增加,薄膜表面呈现自仿射性质。动力学标度方法定量分析表明:薄膜表面因不同N2流量的影响而具有不同的动力学指数,当氮气流量比为5%时,静态标度指数α≈0 65,生长指数β≈0 53±0 02,薄膜生长符合基于Kolmogorov提出的能量波动概念的KPZ模型指数规律。     

ZnO薄膜的分子束外延生长及性能

利用分子束外延(MBE)和氧等离子体源辅助MBE方法分别在Si(100)、GaAs(100)和蓝宝石Al2O3(0001)衬底上用Zn、ZnS或以一定Zn-O化学计量比作缓冲层,改变衬底生长温度和氧压,并在氧气氛下,进行原位退火处理,得到ZnO薄膜。依据X射线衍射(XRD)图,表明样品的结晶性能尚好,且呈c轴择优取向;实验结果表明在不同衬底上生长的ZnO薄膜,由于晶格失配度不同,其衍射峰也有区别。用原子力显微镜(AFM)观测薄膜的表面形貌,为晶粒尺寸约几十纳米的ZnO纳米晶,且ZnO晶粒呈六边形柱状垂直于衬底的表面。采用掠入射X射线反射率法测膜厚。在360nm激发下,样品的发光光谱是峰值为410,510nm的双峰谱,是与样品表面氧缺陷有关的深能级发光。     

正轴6H-SiC 衬底上3C-SiC薄膜的低压化学气相沉积生长

活性的O-和OH-被认为在苯酚形成过程中起了重要作用．通过低压化学气相沉积，在正轴6H-SiC(0001)衬底上沉积了3C-SiC薄膜，X射线衍射表明薄膜结晶质量良好．研究了生长参数对生长速率的影响，发现硅烷及其分解产物的输运是薄膜生长的限定因素．用原子力显微镜观察薄膜的表面形貌．这些结果表明薄膜的生长符合S-K方式．     

ZnO／AlN／Si（111）薄膜的外延生长和性能研究

用常压金属化学气相沉积法(MOCVD)在Si(111)衬底上制备了马赛克结构ZnO单晶薄膜。引入低温Al N缓冲层以阻止衬底氧化、缓解热失配和晶格失配。薄膜双晶X射线衍射2θ/ω联动扫描只出现了Si(111)、ZnO(000l)及Al N(000l)的衍射峰。ZnO/Al N/Si(111)薄膜C方向晶格常量为0.5195nm,表明在面方向处于张应力状态;其对称(0002)面和斜对称(1012)面的双晶X射线衍ω摇摆曲线半峰全宽分别为460″和1105″;干涉显微镜观察其表面有微裂纹,裂纹密度为20cm-1;3μm×3μm范围的原子力显微镜均方根粗糙度为1.5nm;激光实时监测曲线表明薄膜为准二维生长,生长速率4.3μm/h。低温10K光致发光光谱观察到了薄膜的自由激子、束缚激子发射及它们的声子伴线。所有结果表明,采用金属化学气相沉积法并引入Al N为缓冲层能有效提高Si(111)衬底上ZnO薄膜的质量。     

FTIR法研究BCN薄膜的内应力

采用射频磁控溅射技术,用六角氮化硼和石墨为溅射靶,以氩气(Ar)和氮气(N₂)为工作气体,在Si(100)衬底上制备出硼碳氮(BCN)薄膜。利用傅里叶变换红外光谱(FTIR)考察了不同沉积参数(溅射功率为80～130 W、衬底温度为300～500 ℃、沉积时间为1～4 h)条件下制备的薄膜样品。实验结果表明,所制备薄膜均实现了原子级化合。并且沉积参数对BCN薄膜的生长和内应力有很大影响,适当改变沉积参数能有效释放BCN薄膜的内应力。在固定其他条件只改变一个沉积参数的情况下,得到制备具有较小内应力的硼碳氮薄膜的最佳沉积条件：溅射功率为80 W、衬底温度为400 ℃、沉积时间为2 h。     

Influence of oxygen on the growth of cubic boron nitride thin films by plasma-enhanced chemical vapour deposition

Cubic boron nitride thin films were deposited on silicon substrates by low-pressure inductively coupled plasma-enhanced chemical vapour deposition. It was found that the introduction of O₂ into the deposition system suppresses both nucleation and growth of cubic boron nitride. At a B₂H₆ concentration of 2.5\% during film deposition, the critical O₂ concentration allowed for the nucleation of cubic boron nitride was found to be less than 1.4\%, while that for the growth of cubic boron nitride was higher than 2.1\%. Moreover, the infrared absorption peak observed at around 1230--1280~cm^-1, frequently detected for cubic boron nitride films prepared using non-ultrahigh vacuum systems, appears to be due to the absorption of boron oxide, a contaminant formed as a result of the oxygen impurity. Therefore, the existence of trace oxygen contamination in boron nitride films can be evaluated qualitatively by this infrared absorption peak.     

The role of hydrogen in hydrogenated microcrystalline silicon film and in deposition process with VHF-PECVD technique

The role of hydrogen in hydrogenated microcrystalline silicon ($\mu $c-Si:H) thin films in deposition processes with very high frequency plasma-enhanced chemical vapour deposition (VHF-PECVD) technique have been investigated in this paper. With \textit{in situ} optical emission spectroscopy (OES) diagnosis during the fabrication of $\mu $c-Si:H thin films under different plasma excitation frequency $\nu _{\rm e }$ (60MHz--90MHz), the characteristic peak intensities ($I_{{\rm SiH}^*}$, $I_{{\rm H}\alpha^*}$ and $I_{{\rm H}\beta ^*}$) in SiHVHF-PECVD技术 氢化微晶硅 光发射光谱 薄膜学VHF-PECVD technique, hydrogenated microcrystalline silicon, role of hydrogen, optical emission spectroscopyProject supported by the Natural Science Foundation of Guangdong Province, China (Grant No 05300378), the State Key Development Program for Basic Research of China (Grant Nos G2000028202 and G2000028203) and the Program on Natural Science of Jinan University, Guangzhou, China (Grant No 51204056).2005-11-252005-11-252006-01-05The role of hydrogen in hydrogenated microcrystalline silicon （μc-Si：H） thin films in deposition processes with very high frequency plasma-enhanced chemical vapour deposition （VHF-PECVD） technique have been investigated in this paper. With in situ optical emission spectroscopy （OES） diagnosis during the fabrication of μc-Si：H thin films under different plasma excitation frequency Ve （60MHz-90MHz）, the characteristic peak intensities （IsiH＊, IHα＊ and IHβ＊ ） in SiH4＋H2 plasma and the ratio of （IHα＊ ＋ IHβ＊ ） to IsiH＊ were measured; all the characteristic peak intensities and the ratio （IHα＊ ＋ IHβ＊ ）/IsiH＊ are increased with plasma excitation frequency. It is identified that high plasma excitation frequency is favourable to promote the decomposition of SiH4＋H2 to produce atomic hydrogen and SiHx radicals. The influences of atomic hydrogen on structural properties and that of SiHx radicals on deposition rate of μc-Si：H thin films have been studied through Raman spectra and thickness measurements, respectively. It can be concluded that both the crystalline volume fraction and deposition rate are enhanced with the increase of plasma excitation frequency, which is in good accord with the OES results. By means of FTIR measurements, hydrogen contents of μc-Si：H thin films deposited at different plasma excitation frequency have been evaluated from the integrated intensity of wagging mode near 640 cm^-1. The hydrogen contents vary from 4% to 5%, which are much lower than those of μc-Si：H films deposited with RF-PECVD technique. This implies that μc-Si：H thin films deposited with VHF-PECVD technique usually have good stability under light-soaking.     

CRYSTALLINE CARBON NITRIDE THIN FILMS DEPOSITED BY MICROWAVE PLASMA CHEMICAL VAPOR DEPOSITION

The crystalline carbon nitride thin films have been prepared on Si (100) substrates using microwave plasma chemical vapor deposition technique. The experimental X-ray diffraction pattern of the films prepared contain all the strong peaks of α-C₃N₄ and β-C₃N₄, but most of the peaks are overlapped.The films are composed of α-C₃N₄ and β-C₃N₄. The N/C atomic ratio is close to the stoichiometric value 1.33. X-ray photoelectron spectroscopic analysis indicated that the binding energies of C 1s and N 1s are 286.43eV and 399.08 eV respectively. The shifts are attributed to the polarization of C-N bond. Both observed Raman and Fourier transform infrared spectra were compared with the theoretical calculations. The results support the existence of C-N covalent bond in α- and β-C₃N₄ mixture.     

化学沉淀法制备硒化铅薄膜

采用化学沉淀的方法沉淀PbSe薄膜,分别加入缓冲剂联氨(方法A)和碘化钾(方法B)。对反应原理进行了分析,对制备过程进行了优化,分别制备出了高质量的PbSe薄膜。采用XRD、SEM、EDS以及红外光谱测试对所制备样品进行了分析。结果表明,两种方法制备均为PbSe多晶薄膜,方法A制备薄膜结晶质量更好,择优生长方向明显;薄膜颗粒度、表面粗糙度都小于方法B;两种薄膜的Pb元素与Se元素比例接近化学计量比,方法B含有少量I元素;两种方法制备样品的吸收边相对带边跃迁都发生蓝移。     

Influence of reaction gas flows on the properties of SiGe:H thin film prepared by plasma assisted reactive thermal chemical vapour deposition

A new preparing technology, very high frequency plasma assisted reactive thermal chemical vapour deposition （VHFPA-RTCVD）, is introduced to prepare SiGe：H thin films on substrate kept at a lower temperature. In the previous work, reactive thermal chemical vapour deposition （I~TCVD） technology was successfully used to prepare SiGe：H thin films, but the temperature of the substrate needed to exceed 400℃. In this work, very high frequency plasma method is used to assist RTCVD technology in reducing the temperature of substrate by largely enhancing the temperature of reacting gases on the surface of the substrate. The growth rate, structural properties, surface morphology, photo- conductivity and dark-conductivity of SiGe：H thin films prepared by this new technology are investigated for films with different germanium concentrations, and the experimental results are discussed.     

Growth of n-type ZnO thin films by using mixture gas of hydrogen and argon

High-quality oxide semiconductor ZnO thin films were prepared on single-crystal sapphire and LaAlOZnO薄膜 氩氢混合气体 薄膜生长 异质结构 薄膜物理学ZnO, PLD, heterostructureProject supported by the National Natural Science Foundation of China (Grant No 19974001) and the National Key Basic Research Special Foundation of China (Grant No NKBRSF G1999064604 and G2000036505).2005-05-309/3/2005 12:00:00 AMHigh-quality oxide semiconductor ZnO thin films were prepared on single-crystal sapphire and baAlO3 substrates by pulsed laser deposition （PLD） in the mixture gas of hydrogen and argon. Low resistivity n-type ZnO thin films with smoother surface were achieved by deposition at 600℃ in 1Pa of the mixture gas. in addition, ferromagnetism was observed in Co-doped ZnO thin films and rectification Ⅰ - Ⅴ curves were found in p-GaN/n-ZnO and p-CdTe/n-ZnO heterostructure junctions. The results indicated that using mixture gas of hydrogen and argon in PLD technique was a flexible method for depositing high-quality n-type oxide semiconductor films, especially for the multilayer thin film devices.     

Heteroepitaxial film growth of layered compounds with the ZrCuSiAs-type and ThCr2Si2-type structures: From Cu-based semiconductors to Fe-based superconductors

FeAs-based layered superconductors such as F-doped LaFeAsO have recently been investigated intensively because of their high superconducting transition temperatures. Epitaxial films of these compounds are important to examine their intrinsic materials properties as well as to transfer them to device applications. In this review, we first present our research route from transparent p-type oxides semiconductors to the Fe-based superconductors. Then we review growth of epitaxial thin films for the layered oxychalcogenides and oxypnictides. Reactive solid-phase epitaxy technique was inevitable to prepare epitaxial thin films of the oxychalcogenides and Zn-based oxypnictides. On the other hand, epitaxial thin films of Mn-based oxypnictides were grown by standard pulsed laser deposition. These techniques, however, did not grow epitaxial thin films for LaFeAsO. Thus, we developed a modified pulsed laser deposition process and succeeded in obtaining epitaxial thin films of FeAs-based superconductors, LaFeAsO and cobalt-doped SrFe₂As₂.