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Formation and characterization of multilayer coatings for X-ray optics
World Abstracts on Microelectronics and Reliability amorphous silicon gap is studied. These current terms are inter-compared and compared with the current terms of a crystalline silicon homojunction of identical doping levels. We have found that the dominant dark current mechanism is multitunnelling across localized states of the amorphous silicon gap. Influence on the electrical characteristics of the - - N H radicals incorporated into PECVD silicon nitride films. O. SANCHEZ, C. GOMEz-ALEIXANDRE,M. FERNANDEZand J. M. ALBELLA. Vacuum 39(7/8), 727 (1989). The electrical and structural properties of silicon nitride films deposited by plasmaenhanced chemical vapour deposition (PECVD) have been investigated. The films were grown using ammonia and silane diluted in nitrogen (2%) as reactants in a wide range of ammonia to silane flow ratios (between 3 and 35) and plasma powers (10-500 W). Only - - N H species were found incorporated into the films. For the stoichiometric samples, a good correlation between the N - - H bond density and the positive charge density was observed. Investigations on structural and optical properties of InP/Ga0.47 In0.s3As superlattices grown by metalorganic chemical vapor deposition. P. MAUR~L, F. OMN~S, M. DEVOURand M. RAZEGm. Revue Technique Thomson-CSF 20/21(2), 239 (1989) (in French). We report in this paper, investigations on structural and optical properties of InP/Gao.47Ino.s3As superlattices, grown by metalorganic chemical vapor deposition. The composition of the layers and the stiffness of the interfaces are now perfectly controlled, after optimization of the growth conditions. We therefore observed excitons at room temperature for the first time in this system. Theoretical investigation of the C-V relationship for an amorphous silicon p - n junction. HSIUNG-KUANGTSA! and S1-CI~N LEE. Solid-St. Electron. 32(9), 727 (1989). The use 8. T H I C K -
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THIN-FILM
COMPONENTS,
Radiation-enhanced adhesion of thin films. J. S. COLLIGON and H. KHEYRANDISH. Vacuum 39(7/8), 705 (1989). A review of recent experimental work on irradiation of thin films by ions, electrons and photons is given. First the principles of the adhesion process and techniques for measurement of adhesion are briefly discussed. Then particular filmsubstrate bilayers are selected to demonstrate improved adhesion under irradiation conditions where either nuclear or electronic energy loss predominates. It is shown that, for certain systems, the movement of secondary electrons across the film-substrate interface is associated with the improved adhesion. The conclusion drawn from the data available, which are mainly from experiments in poor vacuum conditions and therefore probably involve contaminant layers, is that electronic energy loss appears to be an important factor. It is suggested that nuclear energy may also be important in moving atoms to appropriate sites at or near to the interface where a rearrangement of electronic bonds may occur. Structure and resistivity of Bi--SiO cermet films. K. SUJATHA and P. JAYARAMAREDDY. Solid-St. Commun. 71(8), 633 (1989). Bi-SiO cermet films were prepared by co-evaporation technique onto Corning glass substrates held at substrate temperatures of 300-450K. XRD and SEM observations show that the films formed (1) at high substrate temperature and (2) with higher content of Bi were polycrystalline with Bi grains distributed in an SiO matrix. The grain size varied from 0.5 to 2.5/zm with the variation of Bi content. The resistivity of films deposited at 423 K was increased by eight orders of magnitude over that of pure Bi by increasing the at.% of SiO to 85%. The films deposited at high substrate temperature were found to be more stable
831
of capacitance-voltage measurement to probe the continuous gap state distribution of hydrogenated amorphous silicon is reconsidered. Since the capacitance is measured by a small a.c. voltage, whereas the data are plotted against d.c. voltage, care must be taken in extracting the gap state density from the slope of the capacitance-voltage curve. It is found that under large reverse bias, the I/C2-V curve of an a-Si:H p +-n junction shows a linear relation, similar to a crystal junction, and that the density obtained is the total gap state charge density. Formation and characterization of multilayer coatings for X-ray optics. J. VERHOEWN,E. PUIK and M. J. VANDERWIEL. Vacuum 39(7/8), 711 (1989). A review is given of the techniques to produce multilayer coatings with a d-spacing in the nanometer range, for application in X-ray optics. Methods to grow the films, to control thickness and to investigate layer boundaries are described. Investigations to obtain multilayer structures with a high energy resolution are discussed. Comparison of the conventional and extended WKB approximatious for tunneling in semiconductors. P. K. CHAKABORTY and J. C. BlSWAS. Solid-St. Electron. 32(8), 633 (1989). The objective of this paper is to examine the relative merits of the conventional WKB (CWKB) and the extended WKB (EWKB) approximations for the study of tunneling in semiconductors. For our purpose we have compared the results of these two approaches with (a) the results yielded by the more rigorous 01"p) perturbation theory, taking into account three-dimensional energymomentum conservation during tunneling, and (b) experimental findings. Among other things, we find that the EWKB approximation is generally more appropriate than the CWKB approximation for the study of interband tunneling. HYBRID
CIRCUITS
AND
MATERIALS
when exposed to the atmosphere for a duration of about 6 months. Calculation of electrical parameters of a thin-fiha multichip package. DEEPAK NAYAK,LIH-TYNG HWANG and IWEONA TURLIK. IEEE Trans. Compon. Hybrids. mfg Technol. 12(2), 303 (1989). Calculations of the electrical parameters of a thin-film multichip package are presented. It is shown that a commonly used 2-D device simulator, PISCES, can be employed to compute the electrical parameters of the thin-film lines up to a frequency where the skin effect is important. For trapezoidal conductor cross-sections, it is shown that the maximum variations of self- and mutal (coupling) capacitances are within 10% of their corresponding rectangular values when the sidewall angle of the conductor is varied up to 30°, and the line cross-section area is kept constant. For the case when the conductor base is kept constant, the variation in mutual capacitance is found to be within 30% and that for self-capacitance is found to be within 12% when the sidewall is varied up to 30°. A simple R - L - C circuit is used to represent a 3-conductor lossy transmission line system, and SPICE is used to analyze the responses in the time domain. A thin-film multichip package design is briefly outlined. An HP-8510 network analyzer is employed to verify the simulation results. Multichip thin-film technology on silicon. R. WAYNE JOHNSON, TIMOTHY L. PHILLIPS, RICHARD C. JAEGER, STEPHEN F. HAHN and DAVID C. BURDEAUX.IEEE Trans. Comport. Hybrids mfg Technol. 12(2), 185 (1989). Packaging is becoming a limiting factor in translating semiconductor speed into system performance. Wafer-scale integration (WSI) approaches this problem by attempting to fabricate
AND
THIN-FILM
COMPONENTS,
Radiation-enhanced adhesion of thin films. J. S. COLLIGON and H. KHEYRANDISH. Vacuum 39(7/8), 705 (1989). A review of recent experimental work on irradiation of thin films by ions, electrons and photons is given. First the principles of the adhesion process and techniques for measurement of adhesion are briefly discussed. Then particular filmsubstrate bilayers are selected to demonstrate improved adhesion under irradiation conditions where either nuclear or electronic energy loss predominates. It is shown that, for certain systems, the movement of secondary electrons across the film-substrate interface is associated with the improved adhesion. The conclusion drawn from the data available, which are mainly from experiments in poor vacuum conditions and therefore probably involve contaminant layers, is that electronic energy loss appears to be an important factor. It is suggested that nuclear energy may also be important in moving atoms to appropriate sites at or near to the interface where a rearrangement of electronic bonds may occur. Structure and resistivity of Bi--SiO cermet films. K. SUJATHA and P. JAYARAMAREDDY. Solid-St. Commun. 71(8), 633 (1989). Bi-SiO cermet films were prepared by co-evaporation technique onto Corning glass substrates held at substrate temperatures of 300-450K. XRD and SEM observations show that the films formed (1) at high substrate temperature and (2) with higher content of Bi were polycrystalline with Bi grains distributed in an SiO matrix. The grain size varied from 0.5 to 2.5/zm with the variation of Bi content. The resistivity of films deposited at 423 K was increased by eight orders of magnitude over that of pure Bi by increasing the at.% of SiO to 85%. The films deposited at high substrate temperature were found to be more stable
831
of capacitance-voltage measurement to probe the continuous gap state distribution of hydrogenated amorphous silicon is reconsidered. Since the capacitance is measured by a small a.c. voltage, whereas the data are plotted against d.c. voltage, care must be taken in extracting the gap state density from the slope of the capacitance-voltage curve. It is found that under large reverse bias, the I/C2-V curve of an a-Si:H p +-n junction shows a linear relation, similar to a crystal junction, and that the density obtained is the total gap state charge density. Formation and characterization of multilayer coatings for X-ray optics. J. VERHOEWN,E. PUIK and M. J. VANDERWIEL. Vacuum 39(7/8), 711 (1989). A review is given of the techniques to produce multilayer coatings with a d-spacing in the nanometer range, for application in X-ray optics. Methods to grow the films, to control thickness and to investigate layer boundaries are described. Investigations to obtain multilayer structures with a high energy resolution are discussed. Comparison of the conventional and extended WKB approximatious for tunneling in semiconductors. P. K. CHAKABORTY and J. C. BlSWAS. Solid-St. Electron. 32(8), 633 (1989). The objective of this paper is to examine the relative merits of the conventional WKB (CWKB) and the extended WKB (EWKB) approximations for the study of tunneling in semiconductors. For our purpose we have compared the results of these two approaches with (a) the results yielded by the more rigorous 01"p) perturbation theory, taking into account three-dimensional energymomentum conservation during tunneling, and (b) experimental findings. Among other things, we find that the EWKB approximation is generally more appropriate than the CWKB approximation for the study of interband tunneling. HYBRID
CIRCUITS
AND
MATERIALS
when exposed to the atmosphere for a duration of about 6 months. Calculation of electrical parameters of a thin-fiha multichip package. DEEPAK NAYAK,LIH-TYNG HWANG and IWEONA TURLIK. IEEE Trans. Compon. Hybrids. mfg Technol. 12(2), 303 (1989). Calculations of the electrical parameters of a thin-film multichip package are presented. It is shown that a commonly used 2-D device simulator, PISCES, can be employed to compute the electrical parameters of the thin-film lines up to a frequency where the skin effect is important. For trapezoidal conductor cross-sections, it is shown that the maximum variations of self- and mutal (coupling) capacitances are within 10% of their corresponding rectangular values when the sidewall angle of the conductor is varied up to 30°, and the line cross-section area is kept constant. For the case when the conductor base is kept constant, the variation in mutual capacitance is found to be within 30% and that for self-capacitance is found to be within 12% when the sidewall is varied up to 30°. A simple R - L - C circuit is used to represent a 3-conductor lossy transmission line system, and SPICE is used to analyze the responses in the time domain. A thin-film multichip package design is briefly outlined. An HP-8510 network analyzer is employed to verify the simulation results. Multichip thin-film technology on silicon. R. WAYNE JOHNSON, TIMOTHY L. PHILLIPS, RICHARD C. JAEGER, STEPHEN F. HAHN and DAVID C. BURDEAUX.IEEE Trans. Comport. Hybrids mfg Technol. 12(2), 185 (1989). Packaging is becoming a limiting factor in translating semiconductor speed into system performance. Wafer-scale integration (WSI) approaches this problem by attempting to fabricate