关键词： C290   A200   78.66.Jg   81.10.Jt   81.40.Ef  

摘要： We have investigated the solid-phase crystallization (SPC) process of a-Si1-xGex:H (x = 0, 0.21,0.67) alloy films by using X-ray diffraction and electron spin resonance measurements. The films were deposited on Coming 1737 glass at 200 degrees C in a plasma-enhanced chemical vapor deposition system using SiH4 and GeH4 gases. The deposited films were then annealed to be crystallized at 600 degrees C in a N-2 atmosphere. The variation of spin densities due to the annealing was found to be strongly related to the variation in the crystalline fraction of the films. It was observed that the SPC process was dominated bq Ge dangling-bonds rather than Si dangling-bonds for Ge-rich samples (x = 0.21 and 0.67). Furthermore, the H evolution time fi om Ge-H bond for I = 0.67 film was significantly faster than for the x = 0.21 film, which was attributed to the composition-dependent Ge-H dissociation energy. (C) 2000 Elsevier Science B.V. All rights reserved.

关键词： Iron alloys  

摘要： The behavior of Au in the course of the primary crystallization process of Fe87Zr7B5Au1 amorphous alloy was examined by use of atom probe field ion microscopy and transmission electron microscopy. In the early stage of crystallization, Au atoms were still distributed uniformly in the amorphous matrix. Au atoms form clusters at a later stage when more alpha-Fe particles are present. The Au clusters were observed to be separated from alpha-Fe particles, indicating that Au clusters do not stimulate nucleation of alpha-Fe particles. During the growth of alpha-Fe grains, cosegregation of Au and Zr occurred without any influence on the alpha-Fe grain growth. We conclude that Au addition has no effect on nanocrystallization of Fe-Zr-B amorphous alloys.

关键词： Semiconducting films  

摘要： Thin films of amorphous silicon-germanium alloy (a-Si1-xGex) were prepared by sputtering silicon and germanium targets with argon in a radio-frequency (rf) magnetron sputtering system. For the film prepared at an rf power of 200 W, the energy gap and the refractive index showed monotonous changes between those for silicon and germanium with a deviation from linearity in the correlating line of the energy gap. The deviation was attributable to the decrease in structural disorder in the film as shown in Tauc coefficient B. For the film prepared at an rf power of 50 W, some deviations of the energy gap and the refractive index from the monotonous changes increased with decreasing x, because of an excess amount of dangling silicon bonds. Fourier transform infrared spectra indicated absorption due to the modes derived from the dangling bonds. The absorption coefficient showed that the deviations of the energy gap and the refractive index at x = 0 were proportional to the excess amount of dangling bonds of silicon. The excess amount of dangling bonds of silicon retarded crystallization in the solid state. (C) 2000 The Electrochemical Society. S0013-4651(99)05-003-X. AU rights reserved.

关键词： Semiconducting films  

摘要： Thin films of amorphous germanium-nitrogen (a-GeNx) alloys were prepared by the reactive sputtering method. The germanium target was sputtered with argon and nitrogen gases in radio-frequency (rf) magnetron sputtering equipment. Changing the composition of the sputtering gas can adjust the composition, x, of the film in the range from 0 to 1.5 and the corresponding optical energy gap in the range from 0.68 to 2.7 eV. The structures of the film are discussed on the basis of measured X-ray photoelectron spectroscopy and Fourier transform infrared spectrometry. The film prepared at an rf power of 200 W includes more defects and structural disorder compared to film prepared at an rf power of 20 W. (C) 1999 The Electrochemical Society. S0013-4651(98)03-032-8. All rights reserved.

关键词： Ge-Si alloys   hydrogen   amorphous semiconductors   semiconductor thin films   plasma deposited coatings   Raman spectra   infrared spectra   secondary ion mass spectra   dark conductivity   photoconductivity   photoluminescence   optical constants   energy gap   band structure   noncrystalline structure  

摘要： Hydrogenated amorphous silicon germanium alloys (a-SiGe:H) have been prepared by rf glow discharge of silane, germane, and hydrogen gas mixture at substrate temperature of 200 and 250 degrees C. The structural properties of the films have been investigated by infrared, Raman, and secondary ion mass spectroscopy. It is found that there is a preferential incorporation of germanium into the film relative to silicon and the films with high germane gas phase composition X-g > 0.4 tend to oxidize in atmosphere. Besides, polysilane is enhanced in the films with low germane gas phase composition. The electrical properties including dark, photo conductivities, and conduction activation energy are measured. As for the optical properties, optical transmission is adopted to determine the optical gap while photoluminescence spectra together with temperature variation are used to study the band tail states of the films. By applying Brodsky's quantum well model, the various optical and electrical properties could be explained successfully. (C) 1998 American Institute of Physics.

关键词： radiofrequency   noncrystalline   LIGHT(ENERGY)   Amorphous films   Argon   tin alloys   Tin   thin films   middle frequency magnetron sputtering   magnetron sputtering   energy gap   Films   METAL ALLOY  

摘要： Thin films of amorphous germanium-tin alloy (a-Ge1-xSnx) have been prepared by sputtering germanium and tin targets with argon in a radio-frequency magnetron sputtering system. X-ray diffraction reveals that the film for x < 0.38 is amorphous but that crystalline beta-Sn is formed in the amorphous film for x greater than or equal to 0.38. The optical energy gap is expressed by Eg = 0.68 - 0.85x [eV] for x < 0.38. The equation also correlates the pseudo-optical energy gap for the GeSn-beta-Sn composite film.

关键词： Zirconium alloys  

摘要： The thermal stability and brazing characteristics of Zi-Br binary amorphous alloys as a new filler metal for joining zirconium alloy were investigated in order to supersede physically vapor-deposited (PVD) beryllium used conventionally with many disadvantages. The Zr1-xBex (0.3 less than or equal to x less than or equal to 0.5) binary amorphous alloys were produced by melt-spinning method. In the selected composition range the Zr-Be amorphous alloys have two crystallization modes which are dependent on beryllium content in alloys. The temperatures and activation energies for crystallization depend on crystallization-mode as well as beryllium content. These amorphous alloys were put into practical use in joining bearing pads on zircaloy cladding sheath. Using Zr-Be amorphous alloys as filler metals, the reduction in thickness of cladding sheath wall are prevented. Especially, in the case of using Zr0.65Be0.35 and Zr0.7Be0.3 amorphous alloys, smooth interface and spherical primary alpha-Zr particles appear in the brazed layer, which is desirable microstructure in the view of the corrosion-resistance. (C) 199S Elsevier Science B.V.

关键词： Germanium alloys  

摘要： Optimized deposition parameters for helium diluted a-SiGe:H material differ from those for hydrogen diluted a-SiGe:H material with the same optical gap(similar to 1.5 eV). Deposition rate of optimized helium diluted film is 3.3 times greater than that of hydrogen diluted film, however the photoconductivities of both type of materials are the same. Defect density (6.72 +/- 1 x 10(15) cm eV(-1)) and Urbach energy (46 +/- 1.5 meV) of helium diluted optimized film is less than corresponding values (8.45 +/- 1 x 10(15) cm(-3) eV(-1), 49 +/- 1.5 meV) of hydrogen diluted alloy materials. Schottky barrier solar cells have been fabricated using both optimized materials. Blue response is greater for the optimized helium diluted a-SiGe:H material than that of optimized hydrogen diluted alloy film. Red response is also greater in the first case in comparison to that in the second case.

关键词： Amorphous alloys  

摘要： A deposition method, in which similar to 3 nm-thick deposition and hydrogen plasma annealing are alternately repeated, has been employed to fabricate hydrogenated amorphous silicon-germanium (a-Si1-3Gex:H) alloys by changing substrate temperatures from 150 to 230 degrees C. The germanium content, x, remains unchanged at about 0.42 independent of the substrate temperature for a molar fraction of SiH4/GeH4=10. The bonded hydrogen concentration decreases with increasing substrate temperature, resulting in a decrease in the optical bandgap from 1.52 to 1.43eV. It is found that a photoconductivity of 4.5 X 10(-5) S/cm and a photosensitivity, 9.1 X 10(4), under AM 1 (100 mW/cm(2)) illumination are obtained at a substrate temperature of 175 degrees C at an optical bandgap of 1.49 eV.

关键词： AMORPHOUS semiconductors   NITROGEN   ALLOYS   CHEMICAL vapor deposition  

摘要： A series of hydrogenated amorphous germanium nitrogen alloys have been prepared by using plasma enhanced chemical vapor deposition system, The structure, optical and electrical properties have been investigated and compared with the samples produced by reactive sputtering method. It is found that inclusion of nitrogen into a-Ge:H network increases the structural stability and induces the significant changes both in optical and electrical properties. Hydrogenated a-GeN films have also been fabricated by using nitridation and high hydrogen dilution technique. These unique features have been described in this article. (C) 1996 American Institute of Physics.