Growth and properties of magnetron cosputtering grown Mn(x)Ge(1-x)on Si(001)

We have grown MnxGe1-x films (x=0, 0.06, 0.1) on Si (001) substrates by magnetron cosputtering, and have explored the resulting structural, morphological, electrical and magnetic properties. X-ray diffraction results show there is no secondary phase except Ge in the Mn0.06Ge0.94 film while new phase appears in the Mn0.1Ge0.9 film. Nanocrystals are formed in the Mn0.06Ge0.94 film, determined by field-emission scanning electron microscopy. Hall measurement indicates that the Mn0.06Ge0.94 film is p-type semiconductor and hole carrier concentration is 6.07 X 10(19) cm(-3) while the MnxGe1-x films with x=0 has n-type carriers. The field dependence of magnetization was measured using alternating gradient magnetometer, and it has been indicated that the Mn0.06Ge0.94 film is ferromagnetic at room temperature. (c) 2005 Elsevier Ltd. All rights reserved.

X-ray evidence for Ge/Si(001) island columns in multilayer structure

A Ge/Si(0 0 1) multilayer structure is investigated by cross-sectional transmission electron microscopy, atomic force microscopy and double crystal X-lay diffraction. We find that the multilayer-structure-related satellite peaks in the rocking curve exhibit a similar nonuniform broadening and rye fit the zero-order peak with two Lorentz lineshapes. The ratio of the integrated intensity of two peaks is approximately equal with the anal ratio of the top Ge layer deposited between the areas that are and are not occupied by islands. It proves the existence of vertical-aligned island columns from the viewpoint of macroscopic dimension. (C) 2001 Elsevier Science B.V. All rights reserved.

Metal-free growth of Si/SiO2 nanowires by annealing SiOx (x < 2) films deposited by PECVD

A new metal catalysis-free method of fabricating Si or SiO2 nanowires (NWs) compatible with Si CMOS technology was proposed by annealing SiOx (x < 2) films deposited by plasma -enhanced chemical vapor deposition (PECVD). The effects of the Si content (x value) and thickness of SiOx films, the annealing process and flowing gas ambient on the NW growth were studied in detail. The results indicated that the SiOx film of a thickness below 300 rim with x value close to 1 was most favorable for NW growth upon annealing at 1000-1150 degrees C in the flowing gas mixture of N-2 and H-2. NWs of 50-100nm in diameter and tens of micrometers in length were synthesized by this method. The formation mechanism was likely to be related to a new type of oxide assisted growth (OAG) mechanism, with Si nanoclusters in SiOx films after phase separation serving as the nuclei for the growth of NWs in SiOx films > 200nm, and SiO molecules from thin SiO, film decomposition inducing the NW growth in films < 100nm. An effective preliminary method to control NW growth direction was also demonstrated by etching trenches in SiOx films followed by annealing.

ESTIMATION OF THE STRAIN STATE OF GEXSI1-X/SI STRAINED-LAYER SUPERLATTICES BY DOUBLE-CRYSTAL X-RAY-DIFFRACTION

20-period strained-layer superlattices of nominal composition and width Ge0.2Si0.8 (5 nm)/Si(25 nm) and Ge0.5Si0.5 (5 nm)/Si(25 nm) were studied by double-crystal X-ray diffraction. The Ge content x was determined by computer simulation of the diffraction features from the superlattice. This method is shown to be independent of the relaxation of the superlattice. Alternatively, x can be obtained from the measured difference DELTAa/a in lattice spacing perpendicular to the growth plane. It is sensitive to the relaxation. Comparing the results obtained in these two different ways, information about the relaxation of the superlattices can be obtained.

KINEMATICAL STUDY OF GEXSI1-X/SI STRAINED-LAYER SUPERLATTICE BY A DOUBLE CRYSTAL X-RAY-DIFFRACTION METHOD

Two samples of nominal 20-period Ge0.20Si0.80(5 nm)/Si(25 nm) and Ge0.5Si0.5(5 nm)/Si(25 nm) strained-layer superlattices (SLSs) were studied by the double-crystal X-ray diffraction method. It is convenient to define the perpendicular strains relative to the average crystal. Computer simulations of the rocking curves were performed using a kinematical step model. An excellent agreement between the measured and simulated satellite patterns is achieved. The dependence of the sensitivity of the rocking curves to the structural parameters of the SLS, such as the alloying concentration x and the layer thicknesses and the L component of the reflection g = (HKL), are clearly demonstrated.

INVESTIGATION OF GAAS/SI MATERIAL BY X-RAY DOUBLE-CRYSTAL DIFFRACTION

GaAs epilayer films on Si substrates grown by molecular-beam epitaxy were investigated by the x-ray double-crystal diffraction method. The rocking curves were recorded for different diffraction vectors of samples. The results show that the unit-cell volumes of GaAs epilayers are smaller than that of the GaAs bulk material. The strained-layer superlattice buffer layer can improve the quality of the film, especially in the surface lamella. The parameter W' = W(expt)/(square-root \gamma-h\/gamma-0/sin 2-theta-B) is introduced to describe the quality of different depths of epilayers. As the x-ray incident angle is increased, W' also increases, that is, the quality of the film deteriorates with increasing penetration distance of the x-ray beam. Therefore, W' can be considered as a parameter that describes the degree of perfection of the epilayer along the depth below the surface. The cross-section transmission electron microscopy observations agree with the results of x-ray double-crystal diffraction.

Assessment of the structural properties of GaAs/Si epilayers using X-ray (004) and (220) reflections

We improved the method previously used to determine the lattice constants and misorientation of GaAs/Si by recording the patterns of X-ray (004) and (220) reflections. The (220) reflection was measured from the (110) cross section of a GaAs/Si epilayer. The structural properties of the GaAs/Si epilayers grown by metal-organic chemical-vapor deposition (MOCVD) using an ultrathin a-Si buffer layer were investigated. The rotation angle of GaAs/Si epilayers grown by MOCVD using an a-Si buffer layer is very small and the lattice constants of these GaAs/Si epilayers agree quite well with elastic theory.

A Multi-Finger Si_(1-x)Ge_x/Si Heterojunction Bipolar Transistor for Wireless Power Amplifier Applications

A large area multi-finger configuration power SiGe HBT device(with an emitter area of about 880μm~2)was fabricated with 2μm double-mesa technology.The maximum DC current gain β is 214.The BV_(CEO) is up to 10V,and the BV_(CBO) is up to 16V with a collector doping concentration of 1×10~(17)cm~(-3) and collector thickness of 400nm.The device exhibits a maximum oscillation frequency f_(max) of 19.3GHz and a cut-off frequency f_T of 18.0GHz at a DC bias point of I_C=30mA and V_(CE)=3V.MSG(maximum stable gain)is 24.5dB,and U(Mason unilateral gain)is 26.6dB at 1GHz.Due to the novel distribution layout,no notable current gain fall-off or thermal effects are observed in the I-V characteristics at high collector current.

不同剂量C离子注入Si单晶中Si_(1-x)C_x合金的形成及其特征

室温下在单晶Si中注入(0.6-1.5)%的C原子，利用高温退火固相外延了Si_(1-x)C_x合金，研究了不同注入剂量下Si_(1-x)C_x合金的形成及其特征，如果注入C原子的浓度小于0.6%，在850-950℃退火过程中，C原子容易与注入产生的损伤缺陷结合，难于形成Si_(1-x)C_x合金相。随注入C原子含量的增加，C原子几乎全部进入晶格位置形成Si_(1-x)C_x合金，但如果注入C原子的浓度达到1.5%，只有部分C原子参与形成Si_(1-x)C_x合金。升高退火温度，Si_(1-x)C_x合金相基本消失。

C离子注入Si中Si_(1-x)C_x合金的形成及其稳定性

利用离子注入和高温退火的方法在Si中生长了C含量为0.6%～1.0%的Si_(1-x)C_x合金，研究了不同注入剂量下Si_(1-x)C_x合金的形成及其在退火过程中的稳定性。如果注入剂量小于引起Si非晶化的剂量，850℃退火后，注入产生的损伤缺陷容易与C原子结合形成缺陷团簇，难于形成Si_(1-x)C_x合金。随着注入C离子剂量的增大，注入产生的损伤增强，容易形成Si_(1-x)C_x合金，但注入的剂量增大到一定程度，Si_(1-x)C_x合金的应变将趋于饱和，即只有部分C原子进入晶格位置形成合金相。Si_(1-x)C_X合金一旦形成，在950℃仍比较稳定，而温度高于1000℃，合金的应力将部分释放。随着合金中C原子浓度的升高，合金的稳定性变差。

Ge_xSi_(1-x)/Si中应变的会聚束电子衍射研究

介绍了会聚束电子衍射(CBED)技术与计算机模拟相结合测定Ge_xSi_(1-x)/Si化学梯度层中应变分布的实验结果，提供了一种高空间分辨率、高灵敏度，且适用于任何材料系中微区晶格常数测定及应变分布研究的技术途径。

使用 X射线衍射技术判定 Si C单晶体的结构和极性（英文）

使用四圆衍射仪和双晶衍射技术，分析了SiC体单晶的结构和极性。SiC单晶体由化学气相淀积法获得。六方{10-15}极图证明了该单晶结构为6H型。三轴晶衍射中的ω模式衍射强度的差异判定了该单晶的Si终端面和C终端面，即极性面。两个面的一、二、三级衍射强度的测量比值与经过散射因子修正后计算的结构振幅平方比值｜F(000L)｜~2/｜F(000-L)｜~2非常吻合。因此，利用极性面的衍射强度差异，可以方便、严格地判断具有类似结构如2H{0001}、4H{0001}及3C-SiC{111}的极性。

Annealing Behavior of Si_(1-x)Ge_x/Si Heterostructures

于2010-11-23批量导入

Photocurrent Measurem entof Si_(1-x)Ge_x/Si Multiple Quantum Wells With Ion Im plantationand Therm al Annealing

于2010-11-23批量导入