Growth of In-Doped PbTe Films on Si Substrates

Data on the evaporation behavior of Pb_{1 – x} In _x (0.10 x 0.70) melts were used to devise a procedure for the growth of vapor-phase In doped PbTe thin films on Si substrates. This approach offers the possibility of growing single-phase, homogeneous Pb_{1 – y} In _y Te films of controlled composition by adjusting the composition and temperature of Pb_{1 – x} In _x (0.10 x 0.50) melts. X-ray diffraction characterization demonstrates that the films grown on Si with no oxide layer consist of slightly misoriented crystallites, with their (100) axes normal to the film surface, whereas the films grown on substrates covered with a SiO₂ layer are polycrystalline, with a strong (100) texture.     

Transport Properties of Ga-Doped PbTe Thin Films on Si Substrates

Thin PbTe films on Si substrates were doped with Ga via annealing in the vapor produced by heating a Ga(l) + GaTe(s) mixture (GaTe(s) + L ₁+ Vequilibrium). Electrical measurements showed that the vapor-phase doping reduced the hole concentration in the films by more than two orders of magnitude. IR irradiation was found to reduce the resistivity of the PbTe films by a factor of 40–100. The films annealed in the vapor over GaTe(s) + L ₁for the longest time exhibited an anomalous temperature variation of resistance, which was interpreted as due to the limited Ga solubility in PbTe.     

Structural Perfection of PbTe Films Doped with Indium during Growth on Si Substrates

Pb_{1 - y} In _y Te films doped during growth are produced by a modified hot-wall method. According to x-ray diffraction and electron microscopy data, the films withy _tot < 0.012 are single-phase. The films with y _tot > 0.014 consist of two (PbTe + InTe) or three (PbTe + InTe + In₂Te₃) phases. The 583-K indium solubility in PbTe is determined in the ternary system Pb-In-Te. The results indicate that two pseudobinary joins, PbTe-InTe and PbTe-In₂Te₃, must be examined in assessing the In solubility in PbTe.     

Growth of Niobium Thin Films on Si Substrates by Pulsed Nd:YAG Laser Deposition

The growth of Nb thin films on Si(100) substrates by pulsed Nd:YAG laser deposition(PLD) under different laser fluences(4-15 J/cm~2) was reported.The influence of laser fluence on ablation rate and deposition rate was discussed.X-ray diffraction(XRD) investigations of the deposited films showed an amorphous structure.The droplet density on the film surface observed by scanning electron microscopy(SEM) analyses was extremely low.It was experimentally proved that the droplets on the film surface originated from liquid phase on the target surface.Profilometric measurements of the deposited Nb films revealed a substantial asymmetry in the film thickness related to the plume deflection effect.The measured electrical resistivity of the Nb film was higher than that of high purity Nb bulk.The present investigations of ablation and deposition process of Nb thin films are related to its potential application in superconducting radio-frequency(SRF) cavities.     

SiO2/Si衬底制备ZnO薄膜及表征

本文报道了利用脉冲激光沉积技术在热氧化p型硅衬底上生长ZnO外延薄膜.引入高阻非晶SiO2缓冲层,有效地降低了检测过程中单晶衬底对ZnO薄膜的电学性能影响.利用XRD,SEM,Hall和PL对其进行研究.结果表明,在衬底温度为500℃时,生长的ZnO薄膜具有优良的晶体质量,电学性能和发光性能.     

大面积YBCO高温超导双面薄膜的生长研究

采用倒筒式直流溅射(ICS)方法,辐射方式加热基片,通过电机带动基片旋转,在两面同时溅射沉积YBCO高温超导双面薄膜。在加热温度为850℃,总压强为35Pa,氧氩比为1∶2,靶基距50mm,基片转速5～40r／min条件下,在20mm×20mm的LaAlO     

Heteroepitaxial Growth and Characterization of 3C-SiC Films on Si Substrates Using LPVCVD

3C-SiC films have been deposited on Si (111) substrates by the low-pressure vertical chemical vapor deposition (LPVCVD) with gas mixtures of SiH4, C3Hg and H2- The growth mechanism of SiC films can be obtained through the observations using field emission scanning electron microscope (FESEM). It is found that the growth process varies from surface control to diffusion control when the deposition temperature increases from 1270 to 1350℃. The X-ray diffraction (XRD) patterns show that the SiC films have good crystallinity and strong preferred orientation. The results of the high resolution transmission electron microscopy (HRTEM) image and the transmission electron diffraction (TED) pattern indicate a peculiar superlattice structure of the film. The values of the binding energy in the high resolution X-ray photoelectron spectra (XPS) further confirm the formation of SiC.     

在Sr 2+ :α-BBO单晶衬底上生长β-BBO薄膜的研究

采用液相外延法、脉冲激光沉积法以及气相传输平衡法在Sr^2＋：α-BBO（001）衬底上生长了质量优异的β-BBO薄膜，对薄膜进行了X射线衍射测试以及双晶摇摆曲线分析，结果表明，采用Sr^2＋：α-BBO单晶作为衬底制备的β-BBO薄膜具有高的择优取向度和低的半峰宽值，同目前制备β-BBO薄膜所采用的其他衬底材料相比，Sr^2＋：α-BBO和β—BBO之间具有结构相似、透光范围匹配以及化学稳定性匹配的优点，表明Sr^2＋：α-BBO单晶将是生长β-BBO薄膜的优异衬底材料．     

Properties of ZnO Thin Films Grown on Si (100) Substrates by Pulsed Laser Deposition

ZnO thin films were grown on Si (100) substrates by pulsed laser deposition using a ZnO target.The substrate temperature was varied in the range of room temperature to 800 ℃,and the oxygen partial pressure of 0.1333 Pa (1 m Torr) to 1333 Pa (10 Torr).The properties of the resulting films were investigated by photoluminescence (PL),grazing incidence X-ray diffraction (GIXRD),X-ray photoelectron spectroscopy (XPS),and field emission scanning electron microscopy (FESEM).Based on the ultraviolet (UV,～380 nm) to...     

Growth Kinetics and Microstructure of PbTe Films Produced on Si and BaF<Subscript>2</Subscript> Substrates by a Modified Hot-Wall Method

Lead telluride films have been grown on Si (100) and BaF₂ (100) substrates by a modified hot-wall method using a graphite reaction chamber. According to X-ray diffraction, X-ray microanalysis, and scanning electron microscopy characterization results, the average growth rate of PbTe films having compositions within the homogeneity range of lead telluride increases with increasing lead vapor partial pressure and decreases with increasing tellurium vapor partial pressure, independent of the nature of the substrate. The rate of PbTe film growth has been shown to be maximal in the initial stage of the process and decrease monotonically over time, independent of the nature of the substrate. Independent of the growth time, the average growth rate of the PbTe films on the Si (100) substrates is considerably higher than that on the BaF₂ (100) substrates. Reflection high-energy electron diffraction data indicate that the texture of the PbTe films on Si (100) corresponds to the substrate orientation and that the misorientation angle of the mosaic blocks does not exceed 20°. On the BaF₂ (100) substrates, we observe epitaxial PbTe film growth with the orientation relationship (100), [011] PbTe ║ (100), [011] BaF₂.     

退火温度对Si基Bi4Ti3O12铁电薄膜微观结构影响研究

采用Sol-Gel工艺制备了Si基Bi4Ti3O12铁电薄膜。研究了退火温度对Si基Bi4Ti3O12薄膜晶相结构、晶粒尺寸及薄膜表面形貌的影响。研究表明，退火温度低于450℃时Bi4Ti3O12薄膜为非晶状态，退火温度在550-850℃范围内均为多晶薄膜，而且随退火温度升高，Bi4Ti3O12薄膜更趋向于沿c轴取向的生长；而晶粒尺寸及薄膜粗糙度随退火温度升高而增大，但在较高温度下增长速度趋缓。     

Si(100)衬底上PLD法制备高取向度AlN薄膜

采用脉冲激光沉积法(PLD),以KrF准分子为脉冲激光源,Si(100)为衬底,同时引 入缓冲层TiN和Ti_0.8Al_0.2N,制备了结晶质量优异的A1N薄膜,X射线衍射(XRD)及反射 式高能电子衍射(RHEED)分析表明A1N薄膜呈(001)取向、二维层状生长.研究发现,薄膜 的生长模式依赖于缓冲层种类,直接在Si衬底上或MgO／Si衬底上的A1N薄膜呈三维岛状生 长;而同时引入缓冲层TiN和Ti_0.8Al_0.2N时,A1N薄膜呈二维层状生长.此外,激光能量密 度大小对A1N薄膜的结晶性有显著的影响,激光能量密度过大,薄膜表面粗糙,有颗粒状沉积 物生成.在氮气气氛中沉积,能使薄膜的取向由(001)改变为(100).     

石英玻璃上生长表面光滑高光透射率的金刚石膜

石英玻璃衬底在金刚石粉和丙酮形成的悬浮液中超声波预处理,有效提高了金刚石成核密度.在最佳预处理和热丝化学气相沉积条件下,成核密度高达1010 cm-2以上.采用HFCVD中四步法生长工艺,制备出了表面粗糙度小于10 nm、膜厚300 nm、晶粒直径100 nm～150 nm、致密、均匀、高质量和高光透射率的金刚石膜,其1 μm～5 μm波段的光透射率达74%～85%.金刚石膜与石英玻璃衬底结合牢固,膜中无裂纹.     

Thermal Properties of GaN Films Grown on Si Substrates

GaN films grown on Si substrates by molecular beam epitaxy with different nitridation times have been investigated. The GaN/Si structural and optical properties were evaluated by transmission electron microscopy, X-ray diffraction, atomic force microscopy, and photoluminescence. The effective thermal conductivity of the GaN/Si system was obtained using the photoacoustic technique, and from these results the nitridation time dependence of the interface thermal conductivity (η) can be evaluated using a two-layer model. An optimal nitridation time for which the GaN crystal quality can be improved was obtained. The variation of the parameter η for different nitridation times can be related to the interface phonon scattering process by the presence of disorder at the GaN/Si interface.     

n-type Polycrystalhne Si Thick Films Deposited on SiN_x-coated Metallurgical Grade Si Substrates

For photovoltaic applications,low-cost SiN_x-coated metallurgical grade silicon(MG-Si) wafers were used as substrates for polycrystalline silicon(poly-Si) thick films deposition at temperatures ranging from 640 to880 ℃ by thermal chemical vapor deposition.X-ray diffraction and Raman results indicated that high-quality poly-Si thick films were deposited at 880 ℃.To obtain n-type poly-Si,the as-deposited poly-Si films were annealed at 880 ℃ capped with a phosphosilicate glass.Electrical properties of the n-type poly-Si thick films were investigated by four-probe and Hall measurements.The carrier concentration and electron mobility of the n-type poly-Si film was estimated to be 1.7 x 10~(19) cm~(-3) and 68.1 cm~2 V~(-1) s~(-1),respectively.Highquality poly-Si thick films deposited on MG-Si wafers are very promising for photovoltaic applications.     

Torsional Oscillator Study of Thin Helium Films on Hydrogen Substrates

We have made torsional oscillator measurements of thin helium films on a Mylar surface preplated with 2 and 5 layers of H ₂ . The minimum ⁴ He coverage needed for superfluidity, or inert layer, n _o on both surfaces is found to be 6 mole/m ² . This is equivalent to 1/2 of a monolayer at bulk liquid density. The superfluid transition in coverages above n _o is similar to that found on bare Mylar, exhibiting the standard Kosterlitz-Thouless characteristics. We find no anomaly in _s or the dissipation in the film that can be identified with a second transition reported in recent third sound experiments.     

射频磁控溅射法制备碲化铅薄膜的X射线衍射分析

采用射频磁控溅射法,在单面抛光的Si(111)衬底上制备了PbTe薄膜,利用X射线衍射法分析了溅射工艺参数如溅射功率、溅射时间、衬底温度以及退火温度对PbTe薄膜的结晶质量的影响。结果表明:在溅射功率为30W,溅射时间为10 min,衬底未加热时制备的薄膜具有最好的〈100〉方向的择优取向性;退火处理可以改善薄膜的结晶质量,并且退火温度越高,薄膜的结晶质量越好。     

栅极绝缘层工艺优化对氢化非晶硅TFT特性的改善

在TFT小型化趋势下,需要进一步提高氢化非晶硅薄膜晶体管的TFT特性,尤其是开态电流特性.本文结合生产实际,阐述了工艺上改善氢化非晶硅开态电流特性的方法,包括提高单位面积栅绝缘层电容和改善载流子迁移率.实验结果表明,降低高速沉积栅绝缘层的气压和厚度,能有效提高单位面积栅极绝缘层电容.增加低速沉积栅绝缘层的Si/N比及优化氢等离子体处理工艺,可以有效改善载流子迁移率.