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- Gustavsson, P., et al.
(författare)
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Time trends in occupational exposure to chemicals in Sweden: proportion exposed, distribution across demographic and labor market strata, and exposure levels
- 2022
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Ingår i: Scandinavian Journal of Work, Environment and Health. - : Scandinavian Journal of Work, Environment and Health. - 0355-3140 .- 1795-990X. ; 48:6, s. 479-489
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Tidskriftsartikel (refereegranskat)abstract
- Objective This study investigated time trends in occupational exposure to various chemicals in Sweden and the distribution across demographic and labor market sectors. Methods Exposure to six chemicals was investigated from 1980 to 2013 by application of a job exposure matrix to national population registers. Respirable crystalline silica (RCS), diesel engine exhaust, welding fumes, wood dust, chlorinated hydrocarbon solvents, and lead were selected to represent different groups of chemicals. Trends in exposure prevalence were investigated by linear regression and compared to the occupationally active popula-tion. Confidence intervals for the rate of change over time were obtained by bootstrapping. Results The proportion of workers born outside the Nordic countries increased over time in those exposed to RCS, diesel exhaust and wood dust. There was a shift of exposed jobs to small companies (<50 employees), especially for RCS, welding fumes, wood dust, and chlorinated hydrocarbon solvents. For RCS and welding fumes, there was a marked drop in exposure levels from 1980 to 1990 but small changes thereafter. Exposure to lead diminished, both in terms of prevalence and intensity. Conclusions Over time, several exposures tended to shift to small companies, the construction sector, and migrant workers, all factors being indicative of less well-controlled working conditions. Occupational exposure to chlorinated organic solvents and lead diminished, while exposure levels to RCS and welding fumes have changed little since 1990. In view of the serious and well-established negative health effects, increased efforts to reduce exposure to RCS and welding fumes are needed.
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- Jacob, A P, et al.
(författare)
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Cryogenic performance of ultrathin oxide MOS capacitors with in situ doped p(+) poly-Si1-xGex and poly-Si gate materials
- 2002
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Ingår i: Semiconductor Science and Technology. - : Iop Publishing Ltd. - 0268-1242 .- 1361-6641. ; 17:9, s. 942-946
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Tidskriftsartikel (refereegranskat)abstract
- A low-temperature electrical characterization of ultrathin oxide MOS capacitors with p(+) poly-Si1-xGex and poly-Si gate is performed. The investigated structures are suitable for future nano-scaled high speed MOSFETs. The aim of this study is to compare the low-temperature performance of poly-Si1-xGex and poly-Si gate MOS structures in the nanoscale channel length regime. Apart from the significant change in the flat band voltage, the result shows that all the poly-Si and poly-Si1-xGex gated MOS structures exhibit two centres of polarity change (zero-temperature coefficients) in capacitance. The second polarity change leads to an exclusive phenomenon in these structures. The low-temperature capacitance is found to be less than high-temperature capacitance at strong accumulation and this is in contrast to what has been observed so far in metal-gated capacitors. It is also observed that the temperature dependence of the tunnelling current is only on the oxide thickness and not on the gate material used.
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- Jacob, AP, et al.
(författare)
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Post-growth process relaxation properties of strained Cd0.92Zn0.08Te/Cd0.83Zn0.17Te quantum well heterostructures grown by molecular beam epitaxy
- 2004
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Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society; 1999. - 1071-1023 .- 1520-8567. ; 22:2, s. 565-569
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Tidskriftsartikel (refereegranskat)abstract
- The post-growth structural stability regarding relaxation and defect propagation in Cd0.83Zn0.17Te/Cd0.92Zn0.08Te/Cd0.83Zn0.17Te quantum well (QW) heterostructures grown on [001] oriented Cd0.88Zn0.12Te substrates at 300degreesC by molecular beam epitaxy is investigated. The investigated heterostructures were subjected to post-growth thermal treatment in an ambient atmosphere in a temperature range between 280 and 550degreesC for 3 It each. We have used high-resolution x-ray diffraction as the main characterization tool. High-resolution rocking curves as well as the powerful two-dimensional reciprocal space mapping were employed in both symmetrical as well as asymmetrical reflections. The results indicate that at a post-growth temperature cycle of 350degreesC for 3 h slight modification of the Cd0.83Zn0.17Te/Cd0.92Zn0.08Te barrier/QW heterointerface smoothness is affected. This indicates the onset of migration of Zn atoms at this post-growth temperature time cycle. At 450 degreesC, this effect is more pronounced and seen as the complete disappearance of thickness fringes. For higher post-growth thermal treatment at 550 degreesC for 3 h, a hi-fi relaxation level accompanied by Zn content reduction is observed. A reduction of the Zn content down to 0.11 fractional value in the thick Cd0.83Zn0.17Te barrier is attributed to Zn out diffusion and/or Zn precipitation. (C) 2004 American Vacuum Society.
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- Jacob, AP, et al.
(författare)
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Ultrathin oxynitridation process through ion implantation in a poly Si1-xGex gate MOS capacitor
- 2003
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier Science B.V., Amsterdam.. - 1369-8001 .- 1873-4081. ; 6:03-Jan, s. 37-41
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Tidskriftsartikel (refereegranskat)abstract
- Effect of temperature and time of heat treatment on the distribution of ion-implanted nitrogen in poly Si0.65Ge0.35 gate MOS samples was studied. Secondary ion mass spectrometry (SIMS) was used for the qualitative analysis of the nitrogen distribution. Rapid thermal processing was carried out for a temperature range of 950-1070degreesC for the redistribution of ions. The nitrogen implantation doses were 5 x 10(14) cm(-2), 2 x 10(15) cm(-2) and 5 x 10(15) cm(-2), all with an implantation energy of 50 keV. For a uniform distribution of nitrogen in the SiO2 region, an optimal temperature at a well calibrated time must be applied and this depends on the implantation dose. For medium and high concentrations the optimal conditions were 1050degreesC and 15s, and 1070degreesC and 15s, respectively. A uniform nitrogen distribution could be obtained throughout the SiO2 film. Prolonged heat treatment can cause degradation of the oxide layer and movement of the nitrogen and oxygen into the channel and the poly-Si0.65Ge0.35 layer.
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