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- Barrigón, E., et al.
(författare)
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GaAs Nanowire pn-Junctions Produced by Low-Cost and High-Throughput Aerotaxy
- 2018
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 18:2, s. 1088-1092
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Tidskriftsartikel (refereegranskat)abstract
- Semiconductor nanowires could significantly boost the functionality and performance of future electronics, light-emitting diodes, and solar cells. However, realizing this potential requires growth methods that enable high-throughput and low-cost production of nanowires with controlled doping. Aerotaxy is an aerosol-based method with extremely high growth rate that does not require a growth substrate, allowing mass-production of high-quality nanowires at a low cost. So far, pn-junctions, a crucial element of solar cells and light-emitting diodes, have not been realized by Aerotaxy growth. Here we report a further development of the Aerotaxy method and demonstrate the growth of GaAs nanowire pn-junctions. Our Aerotaxy system uses an aerosol generator for producing the catalytic seed particles, together with a growth reactor with multiple consecutive chambers for growth of material with different dopants. We show that the produced nanowire pn-junctions have excellent diode characteristics with a rectification ratio of >105, an ideality factor around 2, and very promising photoresponse. Using electron beam induced current and hyperspectral cathodoluminescence, we determined the location of the pn-junction and show that the grown nanowires have high doping levels, as well as electrical properties and diffusion lengths comparable to nanowires grown using metal organic vapor phase epitaxy. Our findings demonstrate that high-quality GaAs nanowire pn-junctions can be produced using a low-cost technique suitable for mass-production, paving the way for industrial-scale production of nanowire-based solar cells.
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- Bratteby, L E, et al.
(författare)
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Whole-body mineral measurements in Swedish adolescents at 17 years compared to 15 years of age.
- 2002
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Ingår i: Acta Paediatrica. - 0803-5253 .- 1651-2227. ; 91:10, s. 1031-8
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To provide reference data for bone mineral variables in 15- and 17-y-old adolescents and to analyse the relationships between these variables and measures of bone and body size, gender, puberty, growth, various lifestyle and environmental factors and socioeconomic background.METHODS: In the same 321 randomly selected adolescents (147 boys and 174 girls) living in two different regions of Sweden, the total bone mineral content (TBMC), bone area (BA) and total bone mineral density (TBMD) were assessed by dual-energy X-ray absorptiometry at ages 15 and 17 y. The effects of bone and body size, gender, growth, sexual maturity, physical activity, region of domicile, social conditions, food habits, smoking and alcohol intake on TBMC and TBMD were examined in multivariate analyses.RESULTS: In the 15-y-old adolescents, BA, height, gender, physical activity, maturity and weight explained 91% and 48%, of the variance in TBMC and TBMD, respectively. In similar analyses in the 17-y-olds, the corresponding figures were 92% and 62%, respectively, when BA, height, growth, physical activity, gender and region emerged as significant in the model. In all these analyses, BA explained most of the variance in TBMC and TBMD. No significant reduction of variance was found when different measures of social conditions, smoking, food habits, alcohol or dietary intakes of energy, calcium or vitamin D were included in the models. The reason why region of domicile had a significant impact on TBMC in the 17-y-olds is not known. The fact that the normal fluoride concentration in drinking water (1.1 mg/L) is 10 times higher in the region where TBMC was higher than in the other region is an interesting observation.CONCLUSION: Almost 90% of the variance in TBMC and 50% of that in TBMD was explained by measures of bone and body size and only a few percent by gender, physical activity, Tanner stage, growth and region of domicile.
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- Carlsson, N, et al.
(författare)
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IMPROVED SIZE HOMOGENEITY OF INP-ON-GAINP STRANSKI-KRASTANOW ISLANDS BY GROWTH ON A THIN GAP INTERFACE LAYER
- 1995
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 156:1-2, s. 23-29
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Tidskriftsartikel (refereegranskat)abstract
- Coherent InP nano-sized islands, embedded into GaInP, have been grown by metal-organic vapour phase epitaxy using the Stranski-Krastanow growth mode. Photoluminescence, atomic force microscopy and transmission electron microscopy studies show that the insertion of a thin ∼ 4 monolayer thick GaP layer affects the critical thickness of the subsequently deposited two-dimensional InP wetting layer, increasing it from ∼ 1.5 monolayers (without an inserted GaP layer) to ∼ 2.5 monolayers (with an inserted GaP layer). We demonstrate that the inserted GaP layer affects also the island formation. The bimodal size distribution of Stranski-Krastanow islands, typical for low InP coverages, can be overcome without island coalescence by deposition on top of the thin GaP layer, where a coverage of InP of about 3.5–4.5 monolayers results in the formation of almost only the larger, fully developed, pyramidal islands. Annealing experiments at growth temperature of 580°C show that these islands (base area ≈ 40 × 50 nm2, height ≈ 10–15 nm, surface density ≈ (1−2) × 109 cm−2) are rather stable in a time-scale over several minutes before they slowly undergo an Ostwald ripening process.
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