Interfacial reactions of cobalt thin films on (001) GaAs

Interfacial reactions between cobalt thin films and (001) GaAs have been studied by transmission electron microscopy, energy-dispersive analysis of x-rays in a scanningTEM, Auger electron spectroscopy and x-ray photoelectron spectroscopy. The completely reacted layer was found to be “β-Ga₂0₃/(CoGa, CoAs)/GaAs.” The formation of a surface layer ofβ-Ga₂O₃ and the use of encapsulated samples minimized As loss from the reacted layer. Both CoGa and CoAs were found to grow epitaxially on (001) GaAs. The orientation relationships between CoGa and GaAs were determined to be [001] CoGa//[001] GaAs and (220) CoGa//(220) GaAs. The Burgers vectors of interfacial dislocations were identified as 1/2 〈101〉 and 1/2 〈011〉 which are inclined to the (001) GaAs surface. Almost all of the CoGa films were found to be epitaxially related to the surface. No interfacial dislocations were observed in most of the epitaxial CoAs films which are considered to be pseudomorphic with respect to GaAs. The orientation relationships between CoAs and GaAs were determined to be [101] CoAs//[011] GaAs and (020) CoAs//(220) GaAs. Two-step annealing was found to be effective in promoting epitaxial growth.     

Cathodoluminescence study of micro-crack-induced stress relief for AlN films on Si(111)

Spatially, spectrally, and depth-resolved cathodoluminescence (CL) measurements were performed for high-quality thin AlN films grown on Si(111). Cl spectra exhibited a sharp peak at 5.960 eV, corresponding to the near-band-edge excitonic emission of AlN. Depth-resolved CL analysis showed that deep level oxygen and carbon impurities are localized primarily at the AlN/Si interface and AlN outer surface. Monochromatic CL imaging of the near-band-edge emission exhibits a spotty pattern, which corresponds to high concentrations of threading dislocations and thermally induced microcracks in the thin layers. We have examined relief of the thermal stress in close proximity to single microcracks and intersecting microcracks. Local CL spectra acquired with a focused e-beam show blue-shifts as large as ∼82 meV in the AlN near-band edge excitonic peaks, reflecting defect-induced reductions in the biaxial thermal stress, which has a maximum value of ∼47 kbar.     

Processing and characterisation of PECVD silicon nitride films

Amorphous Si-N films are synthesised from an NH₃/SiH₄ gas mixture by plasma-enhanced chemical vapour deposition (PECVD) at fixed radio frequency (13.56 MHz) and total gas pressure (34 ± 4 Torr). The variable process parameters and their ranges are: (i) substrate temperature, 200–400°C; (ii) RF power density, 0.08–0.35 W cm⁻²; (iii) NH₃/SiH₄ flow ratio, 40:400–40: 1200 ml min⁻¹. Fundamental properties of the Si-N films are characterised through elemental composition, chemical speciation, optical and electrical properties, all of which are dependent on the process parameters.     

Structural and optical properties of Cd_(0.8)Zn_(0.2)S thin films

Cd_(1-x)Zn_xS thin films were deposited on glass substrates by a vacuum coevaporation method.The structural,compositional,and optical properties of as-deposited Cd_(0.8)Zn_(0.2)S films were investigated using X-ray diffraction(XRD),X-ray fluorescence(XRF),X-ray photoelectron spectroscopy(XPS),and optical transmittance spectrum.The thin films are hexagonal in structure,with strong preferential orientation along the(002) planes.The composition of Cd_(1-x)Zn_xS thin films monitored by a quartz crystal oscil...     

Some properties of chemically vapor deposited films of AlxOyNz on silicon

Transmission electron microscopy (TEM) studies of films prepared in the AlN-Al₂O₃ pseudobinary system by chemical vapor deposition (as described in a companion paper entitled, “Chemical Vapor Deposition of Al_xO_yN_z Films”) indicates that four different phases can be obtained by altering the NH₃/CO₂ gas ratio and preparation temperature. Films prepared at 900°C yield three polycrystalline phases and an amorphous composition. From zero to 25 at. percent O an AlN phase is observed. Amorphous material is observed from 25 to 47 at. percent O. From 47 to 59 at. percent O an Al_xO_yN_z spinel is observed. At 60 at. percent O (pure Al₂O₃) an alumina phase is observed (KI phase). For 770°C films the AlN phase is observed from zero to 8 at. percent 0; from 8 to 23 at. percent O the zeta-alumina phase is seen; and at 60 at. percent O the KI alumina phase is again observed. For both the 770 and 900°C films, the grain size of the AlN phase was found to decrease with increasing oxygen content. Direct current-voltage, dielectric breakdown and capacitance-voltage measurements were performed on the 900 and 770°C films with a variety of film compositions. For pure AlN and Al₂O₃, current-voltage and dielectric breakdown measurements correlate with the grain size observed by TEM. A maximum in breakdown field was observed for 900°C films at the composition which yielded minimum grain size of the AlN phase. A similar maximum is observed for the zeta-Al₂O₃ phase of the 770°C films. Positive flatband voltages and hysteresis of the capacitance-voltage trace was observed for most samples. Dielectric constants greater than 8 have been observed for some compositions. Several compositions appear to be attractive candidates for charge storage layers in MIOS devices.     

在(111)Si衬底上磁控溅射纳米SiC薄膜的退火效应

用射频磁控溅射法在常温硅衬底上制备出了纳米碳化硅薄膜,并研究了退火温度对薄膜的影响。用傅里叶红外透射谱（FTIR）、x射线衍射（XRD）、x光电子能谱（XPS）及原子力显微镜（AFM）对薄膜样品进行了结构、组分和形貌分析。AFM表明,随着退火温度的升高,碳化硅颗粒尺寸增大;在高于1000℃退火3h后,碳化硅颗粒呈现出勺状拖尾。     

Growth and characterization of hot-wall epitaxial CdTe on (111) HgCdTe and CdZnTe substrates

Thin CdTe films were deposited by hot-wall epitaxy (HWE) on (111) HgCdTe and CdZnTe substrates at temperatures from about 140 to 335°C. X-ray rocking curves were used to show that crystal quality of the CdTe (111)B films improved as substrate temperature increased from 140 to about 250°C. Rocking curve values for full width at half maximum (FWHM) decreased from 2–4 degrees at 140–150°C to less than 100 arc-s at 250°C, and a FWHM of 59 arc-s was the lowest value observed near 250°C. The FWHM of the HWE CdTe was found to be insensitive to growth rate below about 400Å/min, but increased to four degrees at 1250Å/min. X-ray diffraction confirmed that films grown on the B-face at higher temperatures were epitaxial, but contained a significant volume fraction, 35% to 50%, of rotational in-plane twins. Electron microscopy confirmed a coarse twin density, and photoluminescence spectra showed an absence of excitonic emission in the HWE films. Simultaneous growth on two (111) HgCdTe substrates with different surface polarities between 230°C and 335°C showed that deposition rate on the A-face decreased relative to that on the B-face as temperature increased. Films grown on the B-face exhibited better surface morphologies than those grown on the A-face.     

锆钛酸铅薄膜腐蚀研究

通过对腐蚀溶液的优化,获得了一种刻蚀效果良好的锆钛酸铅(PZT)薄膜的腐蚀溶液配方。文中所采用的PZT薄膜是通过溶胶?蛳凝胶(sol?蛳gel)法获得的,在研究腐蚀溶液组分、温度以及浓度对腐蚀速率影响的基础上,成功获得了PZT薄膜微图形化的湿法腐蚀工艺。通过实验研究,获得了横向和纵向腐蚀速率随温度和浓度变化曲线,侧蚀比（横比纵）小于1:1.07,且图形表面无残留物。     

Atmospheric pressure chemical vapor deposition of blanket tungsten films on silicon substrates for integrated circuit applications

Atmospheric pressure chemical vapor deposition (APCVD) of tungsten films using WF₆/H₂ chemistry has been studied. A statistical design of experiments approach and a surface response methodology were used to determine the most important process parameters and to obtain the best quality film possible in the parameter range studied. It was found that the deposition rate depends strongly on WF₆ flow rate, temperature, and the interaction between hydrogen flow rate and temperature. The resistivity was found to have a strong dependence on WF₆ and H₂ flow rates and temperature. An activation energy of 0.4 eV was calculated for the reaction rate limited growth regime. Empirical equations for predicting the deposition rate and resistivity were obtained. The resistivity decreases with both increasing film thickness and grain size. The films grown in the studied process parameter range indicate that (110) is the preferred orientation for films deposited with low WF₆/H₂ flow rate ratios at all deposition temperatures (350–450°C), whereas, the (222) orientation dominates at high WF₆/H₂ flow ratios and high deposition temperatures. Also, the grain size is larger for (222) oriented films than for (110) oriented films. The results of this study suggest that high-quality, thin film tungsten can be deposited using APCVD.     

氮化Si基ZnO/Ga_2O_3制备GaN薄膜

利用射频磁控溅射法在Si衬底上先溅射ZnO缓冲层,接着溅射Ga2O3薄膜,然后ZnO/Ga2O3膜在管式炉中常压下通氨气进行氮化,反应自组生成GaN薄膜。XRD测量结果表明,利用该方法制备的GaN薄膜是沿c轴方向择优生长的六角纤锌矿多晶结构的薄膜,利用SEM观测了其表面形貌,PL测量结果发现了位于351nm处的室温光致发光峰。     

NiAl(110)和Cu-Al(111)合金表面生长超薄氧化铝膜的畴界和厚度的STM研究

利用低温超高真空扫描隧道显微术研究了在NiAl(110)和Cu-Al( 111)合金衬底上氧化生长的超薄氧化铝膜的畴界和厚度.在这两种氧化铝薄膜上均观察到两种不同类型的畴界:反相畴界(antiphase domain boundary)和反射畴界( reflection domain boundary).结果显示Cu-...     

Rapid thermal annealing of cerium dioxide thin films sputtered onto silicon (111) substrates: Influence of heating rate on microstructure and electrical properties

The impact of the heating rate (HR) of a Rapid Thermal Annealing (RTA) on the crystallinity and on the morphology of CeO₂ thin films has been investigated by Raman Spectroscopy (RS), Photoluminescence (PL), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and tapping mode Atomic Force Microscopy (AFM). The electrical properties of CeO₂ thin films have also been studied with the Conductive AFM mode. This paper highlights the importance of the heating rate value used during an RTA on crystalline quality, morphology and on the electrical properties of the CeO₂ layer. In fact, the best crystallinity with a good morphology and a high resistivity has been obtained for a CeO₂ layer sputtered on (111) Si substrate and post-annealed at 1000 °C for 30 s with an HR of 25 °C/s.     

硅(001)衬底上生长的ZnO薄膜的AFM研究

对采用电子束反应蒸镀方法在低温下在硅（001）衬底上外延生长的ZnO薄膜的表面构像进行了原子力显微镜（AFM）观察,分析研究不同的衬底温度对薄膜表面形貌及结构特性的影响。在250℃衬底温度下获得的ZnO薄膜,膜表面平整,结构致密,表面平均不平整度小于3nm,说明在该衬底温度下获得的ZnO薄膜是高透明度、高质量、高度取向的单晶薄膜。     

Si(111)和Si(100)衬底上磁控反应溅射制备AlN薄膜

采用射频磁控反应溅射法在Si(111)和Si(100)两种衬底上制备了AlN薄膜,用X射线衍射(XRD)对AlN薄膜进行了表征,研究了衬底Si(111)、Si(100)取向以及N2百分比对AlN(002)薄膜c-轴择优取向的影响。实验结果表明,Si(100)较适合生长c-轴择优取向AlN薄膜,而且N2百分比为40%时,AlN薄膜的c-轴取向最好,具有尖锐的XRD峰,此时对应于AlN(002)晶向。计算了(002)取向AlN和两种Si衬底的失配度,Si(111)面与AlN(002)面可归结为正三角形晶系之间的匹配,失配度为23.5%;而Si(100)面与AlN(002)面可归结为正方形晶系与正三角形晶系之间的匹配,失配度为0.8%,可以认为完全共格。理论分析和实验结果相符。     

基于黑硅吸收层的多层组合纳米膜红外探测器敏感元件的制备及研究

采用sol-gel（溶胶-凝胶）技术在SOI 基底上制备了多层组合结构的纳米薄膜（PT/PZT/PT～PT/PZT/PT）,采取金属键合技术,将薄膜作为敏感元件翻转与另一高热阻抗基底对接键合,然后腐蚀SOI 上的底层硅和氧化硅,最终SOI 材料上制备出具有锥状森林结构的黑硅作为吸收层得到一种新颖的敏感元件。重点开展高检测性能的薄膜结构和黑硅吸收层的加工工艺及其敏感机理研究,为实现气体传感器微型化、集成化与批量生产奠定技术基础。     

直流磁控溅射制备非晶硅薄膜的研究

非晶硅薄膜（a-Si）是目前重要的光敏材料,在很多领域得到广泛应用。直流磁控溅射具有工艺简单．沉积温度低等优点,是制备薄膜的一种重要技术。采用直流磁控溅射工艺在玻璃基板上沉积薄膜,并对样品进行了退火处理。研究了沉积速率与溅射功率的关系。结果表明薄膜的沉积速率与溅射功率近似有线性关系。利用X射线衍射（XRD）对薄膜进行了分析鉴定,结果表明溅射的薄膜是非晶硅薄膜。利用扫描电子显微镜（SEM）对非晶硅薄膜的表面形貌进行了观察和分析,与X射线衍射测试的结果一致。所以．利用直流磁控溅射工艺能在常温下能快速制备出良好的非晶硅薄膜。     

在Si(111)上磁控溅射碳化硅薄膜的H2退火效应

用射频磁控溅射法在常温硅衬底上制备了碳化硅薄膜并研究了氢退火对薄膜的影响.用傅里叶红外透射谱(FTIR)、X射线衍射(XRD)、X光电子能谱(XPS)、扫描电镜(SEM)及原子力显微镜(AFM)对薄膜样品进行了结构、组分和形貌分析.结果表明:高温退火后SiC膜的晶化程度明显提高,而且在薄膜中观察到了碳纳米线的形成.     

Si(001)外延ZnSe薄膜界面原子的结合与成键

基于密度泛函理论的第一性原理计算,通过对Si(001)和氮化Si(001)表面单层Zn/Se原子结合的方式,模拟ZnSe外延薄膜的二维生长模式,从单层原子结合能、界面原子电子得失、共价结合成键的角度解释了Zn/Se原子在衬底表面的黏附性问题,阐述了薄膜生长初期界面无定形Se出现等现象,分析了氮化Si(001)表面对薄膜二维均匀生长的作用,结果显示N的引入缓和了Si衬底的非极性共价结合与ZnSe原子间的极性离子键结合之间的异质差异。     

脉冲激光沉积β-FeSi2/Si(111)薄膜的工艺条件

用FeSi2合金靶作为靶材,采用准分子激光沉积法在Si(111)单晶基片上制备了单相的-βFeSi2薄膜,并将飞秒脉冲激光沉积法(PLD)引入到-βFeSi2薄膜的制备工艺中;用X射线衍射仪(XRD),场扫描电镜(FSEM),能谱仪(EDS),紫外可见光光谱仪研究了薄膜的结构、组分、表面形貌和光学性能。基片温度为500℃,采用KrF准分子脉冲激光沉积法可获得单相的-βFeSi2薄膜。衬底温度为550℃时,-βFeSi2出现迷津状薄层。采用飞秒脉冲激光法-βFeSi2薄膜的合成温度比准分子脉冲激光沉积法制备温度低50~100℃;薄膜的晶粒分布均匀连续,没有微米级的微滴;飞秒脉冲激光沉积效率比准分子激光的高1000倍以上,是一种快速高效的-βFeSi2薄膜沉积技术。     

含氢非晶碳膜(a-C:H)红外光学特性的研究

采用端部霍尔离子源在硅基底上制备了含氢非晶碳膜（a-C:H）,并测量了4 000~1 500 cm-1的红外透射光谱。基于单层薄膜的透射关系,获得了仅有六个拟合参数的光学常数计算模型。利用该模型,可以同时获得薄膜在宽波段范围内的光学常数和厚度:折射率的最大值为1.94,消光系数的最大值为0.014 9,拟合薄膜厚度为617 nm 。