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Fabrication of ultrathin unsupported foils
Classified abstracts 6476 6484
used previously in conjunction with C E M compatibility tests of certain epoxies, solder, and fluorocarbon polymer materials useful for construction of spaceflight sensors. While some C E M gain degradation was noted during exposure to Viton and Apiezon-L, the present test indicates that, at least over instrument lifetimes of ~ 2 x 1 0 ~2 counts, these materials should be suitable for (1) preflight space sensor testing systems, (2) hermetic seals for CEM-based space sensors, and (3) terrestrial CEMbased instrumentation. D J McComas et ai, Rev Sci Instrum, 58, 1987, 2331 2332.
method with a d.c. glow discharge of oxygen. The structure and composition of the films were characterized by M6ssbauer spectroscopy, Xray diffraction and scanning electron microscopy. The valency of tin atoms in the films determined by M6ssbauer spectroscopy is mostly divalent in the samples prepared without discharge, but mostly tetravalent in the samples prepared with discharge. Measurements of electrical conductivity and Hall mobility were also carried out and the data were found to correlate with the concentration ratio [Sn4+]/[Sn 2+] determined from M6ssbauer spectroscopy. I M Uen et al, Thin Solid Films, 158, 1988, 69 80.
II. Thin film t e c h n o l o g y
20 6481. Correlation of process and system parameters with structure and properties of physically vapour-deposited hard coatings The effect of the process parameter, substrate bias, on the internal stress, microstructure and hardness of sputter ion-plated titanium nitride (TIN) coatings has been investigated. It is found that high bias levels result in coatings of fine grain size, high internal stress, low porosity and high hardness. The role of the thermal mismatch contribution to internal stress in densification of the coating is elucidated. "Hardness anisotropy" has been observed when indenting plan and cross-sections of thick (about 20 pro) TiN and tungsten titanium carbide coatings. An explanation for this behaviour has been proposed in terms of the microstructural anisotropy of the coatings coupled with the internal stress state acting within the test surface. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction studies of coating morphology, grain size, defect density and texture have been performed and the results obtained used to estimate the relative contributions of grain size and defect density to coating hardness using a simple Hall Petch approach. D S Rickerby and P J Burnett, Thin Solid Films, 157, 1988, 195 222.
20. E V A P O R A T I O N 20 6476. Effects of oxygen partial pressure on the properties of reactively evaporated thin films of indium oxide Thin films of indium oxide were prepared by evaporating indium in the presence of oxygen. The effects of varying the oxygen partial pressure on the optical, electrical and structural properties were investigated. Films evaporated under the optimum oxygen partial pressure of 0.133 Pa exhibited a resistivity of 4.8 x 10 4 ~r~cm and a transmittance of more than 80% at wavelengths of 600 n m and above, for a film thickness of 225 nm. All the films, in the range of partial pressure of oxygen used, were found to be n type. The films showed a b.c.c, structure with a0 = 1.0118 n m and a preferred orientation along the (400) axis. S Naseem et al, Thin Solid Films, 156, 1988, 161 171. 20 6477. Films of rare earth oxides formed by electron beam evaporation Rare earth oxides can effectively be deposited by electron beam evaporation. The films thus formed are dense and non-porous and adhere to various metal substrates. The strength of the bond between the films and the substrates is greatly affected by the treatment of the substrate prior to deposition (the substrate needs to be roughened). The structure of the films is affected to a small degree by the substrate condition and deposition parameters. The orientation of the films is dependent on the substrate temperature. The characteristics of erbium oxide and yttrium oxide films are presented. R O Adams et al, Thin Solid Films, 154, 1987, 101 108. 20 6478. The initial nucleation and growth of gold on sodium chloride for substrate temperatures between 123 and 448 K New experimental data are presented for the nucleation and initial stages of growth of gold films vapour deposited onto ultrahigh-vacuum-cleaved sodium chloride substrates. Substrate temperatures ranging from 123 to 448 K were used and this represents the first reported study of this system at temperatures below room temperature. Special attention has been given to eliminating the possibility that the deposits are affected by low energy electrons originating in the vapour source. This essentially descriptive report presents the new data and draws general conclusions as to the mechanisms operative in these experiments. The experimental evidence suggests that cluster mobility is a dominant process even down to a temperature of 133 K. B F Usher and J L Robins, Thin Solid Films, 155, 1987, 267 283. 20 6479. Growth and characterization of indium teguride thin films Thin films of indium telluride prepared by conventional vacuum evaporation techniques are often non-stoichiometric because of fractionation. Hence, in an attempt to obtain stoichiometric films, non-stoichiometric bulk was used. It is observed that a bulk with a composition ln: Te - 55.7:44.3 (atomic per cent) yields stoichiometric films. The effect of deposition temperature and annealing at elevated temperatures has been studied in detail. The results indicate that an increase in the deposition temperature results in the re-evaporation of tellurium from the films whereas indium-deficient films are obtained on annealing at elevated temperatures. Roughieh Rousina and G K Shivakumar, Thin Solid Films, 157, 1988, 345 350. 20 6480. Preparation and characterization of some tin oxide films Tin oxide films were successfully prepared by the reactive evaporation 492
20 6482. Fabrication of ultrathin unsupported foils The fabrication of self-supporting unbacked foils of 200-~ gold, 500-/~ chromium and titanium, and 1000-/~ a l u m i n u m oxide, titanium oxide, and zirconium oxide by electron beam evaporation is described. This technology is presented in sufficient detail to permit duplication and general procedures useful in predicting the m i n i m u m possible foil thickness are presented. Edward B Graper, J Vac Sci Technol, A6, 1988, 1768 4769. 20 6483. Control of ion bombardment energy in the low-temperature deposition of highly transparent and conducting In203 and ZnO thin films by activated reactive evaporation Highly transparent and conducting 1n203 and Z n O films have been successfully deposited at temperatures as low as < 7 0 ' C by activated reactive evaporation. Ways to control the anode-to-film potential, which can be used as a rough measure of ion b o m b a r d m e n t energy, are discussed. It was found that a m i n i m u m anode-to-film voltage of ~ 20 V is necessary for high mobility ( ~ 18 cm 2 V ~ s ~) for In203. However, for the case of ZnO, it was found that there is no such m i n i m u m ion b o m b a r d m e n t energy. X-ray diffraction data on low-temperature deposited In203 and Z n O films are also presented, showing that Z n O films are in general easier to crystallize than In203 films. A postulate was also made that microvoids can be filled up more easily in the case of zinc oxide deposition because the low sticking coefficient of zinc allows its vapor to go around corners more easily and thus the process is not pure physical vapor deposition but has a substantial c o m p o n e n t that behaves like a surface rate-limited chemical vapor deposition process. Hence the explanation is simply that very little energy is necessary to get Z n O films with an electron mobility of ~ 4 0 cm 2 V ~ s ~ by activated reactive evaporation. This is, however, not the case for sputtering and thus this may have an important implication that there can be less ion damage on some sensitive substrates for low-temperature deposition of Z n O by activated reactive evaporation. W S Lau, J Vac Sci Technol, A6, 1988, 2015 2019 20 6484. Repeated deposition studies of the occurrence of large scale coalescence and effect of electric field on the ageing of island silver films Presented in this paper are the results of an investigation into the influence of a dc electric field on the growth and post-deposition resistance changes in island Ag-films deposited on glass substrates at room temperature. Based on the functional dependence of the film resistance on time, an agglomeration rate is defined with the theory of mobility coalescence
used previously in conjunction with C E M compatibility tests of certain epoxies, solder, and fluorocarbon polymer materials useful for construction of spaceflight sensors. While some C E M gain degradation was noted during exposure to Viton and Apiezon-L, the present test indicates that, at least over instrument lifetimes of ~ 2 x 1 0 ~2 counts, these materials should be suitable for (1) preflight space sensor testing systems, (2) hermetic seals for CEM-based space sensors, and (3) terrestrial CEMbased instrumentation. D J McComas et ai, Rev Sci Instrum, 58, 1987, 2331 2332.
method with a d.c. glow discharge of oxygen. The structure and composition of the films were characterized by M6ssbauer spectroscopy, Xray diffraction and scanning electron microscopy. The valency of tin atoms in the films determined by M6ssbauer spectroscopy is mostly divalent in the samples prepared without discharge, but mostly tetravalent in the samples prepared with discharge. Measurements of electrical conductivity and Hall mobility were also carried out and the data were found to correlate with the concentration ratio [Sn4+]/[Sn 2+] determined from M6ssbauer spectroscopy. I M Uen et al, Thin Solid Films, 158, 1988, 69 80.
II. Thin film t e c h n o l o g y
20 6481. Correlation of process and system parameters with structure and properties of physically vapour-deposited hard coatings The effect of the process parameter, substrate bias, on the internal stress, microstructure and hardness of sputter ion-plated titanium nitride (TIN) coatings has been investigated. It is found that high bias levels result in coatings of fine grain size, high internal stress, low porosity and high hardness. The role of the thermal mismatch contribution to internal stress in densification of the coating is elucidated. "Hardness anisotropy" has been observed when indenting plan and cross-sections of thick (about 20 pro) TiN and tungsten titanium carbide coatings. An explanation for this behaviour has been proposed in terms of the microstructural anisotropy of the coatings coupled with the internal stress state acting within the test surface. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction studies of coating morphology, grain size, defect density and texture have been performed and the results obtained used to estimate the relative contributions of grain size and defect density to coating hardness using a simple Hall Petch approach. D S Rickerby and P J Burnett, Thin Solid Films, 157, 1988, 195 222.
20. E V A P O R A T I O N 20 6476. Effects of oxygen partial pressure on the properties of reactively evaporated thin films of indium oxide Thin films of indium oxide were prepared by evaporating indium in the presence of oxygen. The effects of varying the oxygen partial pressure on the optical, electrical and structural properties were investigated. Films evaporated under the optimum oxygen partial pressure of 0.133 Pa exhibited a resistivity of 4.8 x 10 4 ~r~cm and a transmittance of more than 80% at wavelengths of 600 n m and above, for a film thickness of 225 nm. All the films, in the range of partial pressure of oxygen used, were found to be n type. The films showed a b.c.c, structure with a0 = 1.0118 n m and a preferred orientation along the (400) axis. S Naseem et al, Thin Solid Films, 156, 1988, 161 171. 20 6477. Films of rare earth oxides formed by electron beam evaporation Rare earth oxides can effectively be deposited by electron beam evaporation. The films thus formed are dense and non-porous and adhere to various metal substrates. The strength of the bond between the films and the substrates is greatly affected by the treatment of the substrate prior to deposition (the substrate needs to be roughened). The structure of the films is affected to a small degree by the substrate condition and deposition parameters. The orientation of the films is dependent on the substrate temperature. The characteristics of erbium oxide and yttrium oxide films are presented. R O Adams et al, Thin Solid Films, 154, 1987, 101 108. 20 6478. The initial nucleation and growth of gold on sodium chloride for substrate temperatures between 123 and 448 K New experimental data are presented for the nucleation and initial stages of growth of gold films vapour deposited onto ultrahigh-vacuum-cleaved sodium chloride substrates. Substrate temperatures ranging from 123 to 448 K were used and this represents the first reported study of this system at temperatures below room temperature. Special attention has been given to eliminating the possibility that the deposits are affected by low energy electrons originating in the vapour source. This essentially descriptive report presents the new data and draws general conclusions as to the mechanisms operative in these experiments. The experimental evidence suggests that cluster mobility is a dominant process even down to a temperature of 133 K. B F Usher and J L Robins, Thin Solid Films, 155, 1987, 267 283. 20 6479. Growth and characterization of indium teguride thin films Thin films of indium telluride prepared by conventional vacuum evaporation techniques are often non-stoichiometric because of fractionation. Hence, in an attempt to obtain stoichiometric films, non-stoichiometric bulk was used. It is observed that a bulk with a composition ln: Te - 55.7:44.3 (atomic per cent) yields stoichiometric films. The effect of deposition temperature and annealing at elevated temperatures has been studied in detail. The results indicate that an increase in the deposition temperature results in the re-evaporation of tellurium from the films whereas indium-deficient films are obtained on annealing at elevated temperatures. Roughieh Rousina and G K Shivakumar, Thin Solid Films, 157, 1988, 345 350. 20 6480. Preparation and characterization of some tin oxide films Tin oxide films were successfully prepared by the reactive evaporation 492
20 6482. Fabrication of ultrathin unsupported foils The fabrication of self-supporting unbacked foils of 200-~ gold, 500-/~ chromium and titanium, and 1000-/~ a l u m i n u m oxide, titanium oxide, and zirconium oxide by electron beam evaporation is described. This technology is presented in sufficient detail to permit duplication and general procedures useful in predicting the m i n i m u m possible foil thickness are presented. Edward B Graper, J Vac Sci Technol, A6, 1988, 1768 4769. 20 6483. Control of ion bombardment energy in the low-temperature deposition of highly transparent and conducting In203 and ZnO thin films by activated reactive evaporation Highly transparent and conducting 1n203 and Z n O films have been successfully deposited at temperatures as low as < 7 0 ' C by activated reactive evaporation. Ways to control the anode-to-film potential, which can be used as a rough measure of ion b o m b a r d m e n t energy, are discussed. It was found that a m i n i m u m anode-to-film voltage of ~ 20 V is necessary for high mobility ( ~ 18 cm 2 V ~ s ~) for In203. However, for the case of ZnO, it was found that there is no such m i n i m u m ion b o m b a r d m e n t energy. X-ray diffraction data on low-temperature deposited In203 and Z n O films are also presented, showing that Z n O films are in general easier to crystallize than In203 films. A postulate was also made that microvoids can be filled up more easily in the case of zinc oxide deposition because the low sticking coefficient of zinc allows its vapor to go around corners more easily and thus the process is not pure physical vapor deposition but has a substantial c o m p o n e n t that behaves like a surface rate-limited chemical vapor deposition process. Hence the explanation is simply that very little energy is necessary to get Z n O films with an electron mobility of ~ 4 0 cm 2 V ~ s ~ by activated reactive evaporation. This is, however, not the case for sputtering and thus this may have an important implication that there can be less ion damage on some sensitive substrates for low-temperature deposition of Z n O by activated reactive evaporation. W S Lau, J Vac Sci Technol, A6, 1988, 2015 2019 20 6484. Repeated deposition studies of the occurrence of large scale coalescence and effect of electric field on the ageing of island silver films Presented in this paper are the results of an investigation into the influence of a dc electric field on the growth and post-deposition resistance changes in island Ag-films deposited on glass substrates at room temperature. Based on the functional dependence of the film resistance on time, an agglomeration rate is defined with the theory of mobility coalescence