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121.
金属有机化学汽相沉积生长InGaN薄膜的研究 总被引:2,自引:1,他引:1
以Al2O3为衬底,采用金属有机汽相沉积(MOCVD)技术在GaN膜上生长了InxGa1-xN薄膜。以卢瑟福背散射/沟道技术和光致发光技术对InxGa1-xN/GaN/Al2O3样品进行了分析,研究表明,金属有机汽相沉积生长高In组分InxGa1-xN薄膜有一最佳TMIn/TEGa摩尔流量比。在一定范围内,降低其摩尔流量比,合金的生长速率增高,In组分提高;进一步降低TMIn/TEGa摩尔流量比,导致In组分下降,研究还表明,InGan薄膜的结晶品质随In组分的增大而下降,InGan薄膜的In组分由0.04增大到0.10,其最低沟道产额比由4.1%增至11.0%。 相似文献
122.
Abstract The thermoelectric and galvanomagnetic properties in the CdxHg1_xTe solid solution samples (x = 0.12; 0.15) irradiated at 300 K by electrons (3.5 MeV; by integrated fluxes up to 1.46 × 1018e/cm2) have been investigated in a wide temperature range 4.2–300 K and in magnetic fields 0–22 kOe. It has been discovered that the electron irradiation of CdxHg1–xTe crystals leads to an increase of the Hall coefficient and a decrease of the thermo e.m.f. sign inversion temperature. The concentrations and mobilities of electron and hole have been calculated on a basis of quantitative analysis of galvanomagnetic data. It has been shown that the kinetic coefficient behavior upon irradiation is due to the Te vacancy-based type radiation defect origin. 相似文献
123.
124.
利用离子注入掺杂技术设计、制作半导体集成器件时,了解离子注入半导体材料的射程分布、射程离散和横向离散规律等是很重要的.用400 keV能量的铒(Er)离子分别与样品表面法线方向成0°,45°和 60°倾角注入碳化硅(6H-SiC)晶体中,利用卢瑟福背散射技术研究了剂量为5×1015 cm-2 的400 keV Er离子注入6H-SiC晶体的横向离散.测出的实验值与TRIM98和SRIM 2006得到的理论模拟值进行了比较,发现实验值跟TRIM98和SRIM
关键词:
离子注入
6H-SiC
卢瑟福背散射技术
横向离散 相似文献
125.
The interest in transient analysis of acoustic waves has been growing in recent years, due to the advance of wide-band sonars. In this paper, a transient analysis method for acoustic backscattering signals is proposed based on the time domain physical optics (TDPO). TDPO is formulated via a theoretical inverse Fourier transform of the conventional physical optics formula used in the frequency domain wave scattering analyses. A hidden surface removal algorithm using an adaptive triangular beam method and a virtual surface concept are adopted to explain shadow effects and multiple reflections among elements, respectively. Numerical analyses are carried out for two kinds of underwater targets: a submarine pressure hull and an idealized submarine, in order to validate the proposed method. The result of the submarine pressure hull shows good agreements between the proposed method and conventional physical optics based on inverse fast Fourier transform. Additionally, the result of the idealized submarine shows that the proposed method is efficient for finding highlights including their contribution to the whole backscattering signal. 相似文献
126.
The Multi-Mode Elastic Peak Electron Spectroscopy (MM-EPES) analysis is confined to incoherent electron elastic scattering and the use of variable primary energy. This experimental method is very sensitive to the surface region of the sample. However, for quantitative interpretation, the MM-EPES method needs jointly a Monte Carlo (MC) computer simulation of electron trajectories in the solid. In the present work, we proposed a new approach to calculate the percentage ηe of elastic reflected electrons by the surface of a sample. This simulation takes into account the surface effects (i.e. surface plasmon), and the atoms arrangement in the substrate. The concept of the surface excitation parameter (SEP) is also presented. Computer simulations were performed on the three low index single crystals of Cu, Au, Si and Ag. The results confirm that the distribution of substrate atoms, according to the crystallographic structure, influences the intensity measured by EPES.A simple prediction formula was proposed to calculate ηe for elastic electrons entering in a Retarding Field Analyzer (RFA) spectrometer which is the apparatus giving experimentally numerical values of the percentage ηe. 相似文献
127.
Janna M. Dlugach Michael I. Mishchenko 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,100(1-3):115-121
We analyze theoretically the effect of particle nonsphericity on the backscattering enhancement factor ζhp in the helicity-preserving channel. Using numerically exact T-matrix and vector radiative-transfer codes, we have performed computations for optically semi-infinite homogeneous layers composed of polydisperse, randomly oriented oblate spheroids with the real part of the refractive index equal to 1.2, 1.4, and 1.6, the imaginary part of the refractive index equal to 0 and 0.01, various values of the equal-surface-area-sphere effective size parameter, and aspect ratios 12. Our computations demonstrate that whereas for spheres ζhp≡2, for spheroids the helicity-preserving enhancement factor can deviate quite significantly from the value 2. The magnitude of this deviation varies substantially with particle microphysical parameters and illumination geometry. 相似文献
128.
S. Thevuthasan V. Shutthanandan Y. Zhang 《Journal of Electron Spectroscopy and Related Phenomena》2006,150(2-3):195-207
High energy ion beam capabilities including Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA) have been very effectively used in environmental science to investigate the ion-exchange mechanisms in glass waste forms and the effects of irradiation in glass and ceramic waste forms in the past. In this study, RBS and NRA along with SIMNRA simulations were used to monitor the Na depletion and D and 18O uptake in alumina silicate glasses, respectively, after the glass coupons were exposed to aqueous solution. These results show that the formation of a reaction layer and an establishment of a region where diffusion limited ion exchange occur in these glasses during exposure to silica-saturated solutions. Different regions including reaction and diffusion regions were identified on the basis of the depth distributions of these elements. In the case of ceramics, damage accumulation was studied as a function of ion dose at different irradiation temperatures. A sigmoidal dependence of relative disorder on the ion dose was observed. The defect-dechanneling factors were calculated for two irradiated regions in SrTiO3 using the critical angles determined from the angular yield curves. The dependence of defect-dechanneling parameter on the incident energy was investigated and it was observed that the generated defects are mostly interstitial atoms and amorphous clusters. Thermal recovery experiments were performed to study the damage recovery processes up to a maximum temperature of 870 K. 相似文献
129.
《Surface and interface analysis : SIA》2006,38(8):1198-1203
The backscattering coefficient of low–medium energy electron beams (from 250 to 10 000 eV) impinging on C/Al double layered thin films was investigated by a Monte Carlo simulation. The aim of the research was to study the behaviour of the backscattering coefficient as a function of the beam primary energy and the thicknesses of the two layers. The backscattering coefficient as a function of the primary energy presents features that can be used to evaluate the thicknesses of the two layers. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
130.
G. González Aguilar M.A. Reis I.M. Miranda Salvado M.E.V. Costa 《Surface science》2006,600(9):1780-1786
SrBi2Ta2O9 (SBT) is a bismuth layered perovskite (BLP) with interesting ferroelectric properties for memories applications. The previous study on the synthesis of seeded and unseeded SBT thin films by the authors [G. González Aguilar, M.E.V. Costa, I.M. Miranda Salvado, J. Eur. Ceram. Soc. 25 (2005) 2331] has shown an increase of the crystallinity of the films and an improvement of the thin film ferroelectric properties when using SBT seeds. However, the detailed role of the seeds as an improver of the thin film properties has not been investigated so far. In the present work we study the role of the seeds, particularly with respect to the reactions between film and (bottom) underlying platinum electrode. The comparison of the results obtained by characterizing the seeded and unseeded thin films via Rutherford backscattering (RBS) and particle induced X-ray emission (PIXE) techniques reveals an effective modification of the substrate-thin film interface by the presence of the seeds. Moreover, the evaluation of the thin film ferroelectric properties by atomic force microscopy (AFM) shows an improvement of the local piezoelectric hysteresis loops by the seeds. These seeding effects as well as those observed in non-stoichiometric SBT thin films with different bismuth contents are used to discuss the barrier-like role of the SBT seeds against reactions between film and the platinum electrode and its contribution to the improvement of the thin film properties. 相似文献