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- Fu, Ying, et al.
(författare)
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Energy band structure and spectral gain characteristics of dilute-nitride zinc blende InGaNAs quantum wells embedded in GaAs and GaNAs barriers
- 2006
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 100:7
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Tidskriftsartikel (refereegranskat)abstract
- The spectral gain characteristics of dilute-nitride zinc blende InxGa1-xNyAs1-y quantum wells embedded in GaNy1As1-y1 barriers have been investigated experimentally and theoretically. Two samples, both with the gain peak at 1300 nm, were studied for comparison. One has a high nitrogen concentration in the quantum well with the surrounding barriers being pure GaAs. The other has a lower and uniform nitrogen concentration in the quantum well and the barriers (GaNAs barriers). Measurements show the redshift of the gain peak induced by the incorporation of nitrogen and difference in the spectral gain characteristics. The energy band structures and spectral gain characteristics are analyzed theoretically using the standard eight-band k center dot p theory. It is shown that the introduction of nitrogen atoms in the GaAs barriers reduces the barrier height for the central quantum well so that the energy sublevels in the conduction band becomes condensed. The condensation of the conduction-band energy sublevels reduces the peak gain and makes the gain spectrum narrower, in agreement with measurements.
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- Han, Y., et al.
(författare)
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Critical Thickness and Radius for Axial Heterostructure Nanowires Using Finite Element Method
- 2009
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 9:5, s. 1921-1925
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Tidskriftsartikel (refereegranskat)abstract
- Finite-element methods are used to simulate a heterostructured nanowire grown on a compliant mesa substrate. The critical thickness is calculated based on the overall energy balance approach. The strain field created by the first pair of misfit dislocations, which offsets the initial coherent strain field, is simulated. The local residual strain is used to calculate the total residual strain energy. The three-dimensional model shows that there exists a radius-dependent critical thickness below which no misfit dislocations could be generated. Moreover, this critical thickness becomes infinity for a radius less than some critical values. The simulated results are in good agreement with the experimental data. The critical radius from this work is smaller than that obtained from previous models that omit the interaction between the initial coherent strain field and the dislocation-induced strain field.
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- Lopez-Egido, Juan R., et al.
(författare)
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Differentially regulated genes in MEN1-transfected BON cells using RT-differential display and oligonucleotide microarrays
- 2009
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Ingår i: Anticancer Research. - 0250-7005 .- 1791-7530. ; 29:6, s. 1859-1866
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Apart from inactivation of the MEN1 gene, the molecular mechanisms involved in tumorigenesis of the endocrine organs and MEN1-associated non-endocrine lesions remain unknown. MATERIALS AND METHODS: In order to learn more about down-stream effects upon MEN1 gene inactivation BON1 cells were transfected with a MEN1 gene construct (BON/M1C), and both RT-differential display and oligonucleotide microarrays were performed. RESULTS: Three genes (SMARCC1, OVCA2 and SRp55) found to be differentially regulated on differential display were corroborated by northern blots on cell line RNA when comparing MEN1 transfected cells with control (empty vector transfection). When comparing two different passages of BON/M1C with two passages of vector control using oligonucleotide microarrays, 25 up-regulated genes and 64 down-regulated genes could be found using a cut-off of >or=1.6 times. CONCLUSION: These findings might contribute to the understanding of the molecular pathways involved in MEN1 tumorigenesis, and may also provide knowledge of genes involved in sporadic endocrine tumorigenesis.
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- Wang, Shu Min, 1963, et al.
(författare)
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Metamorphic InGaAs quantum wells for light emission at 1.3-1.6 μm
- 2007
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 515:10, s. 4348-4351
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Tidskriftsartikel (refereegranskat)abstract
- Metamorphic InGaAs quantum well structures grown on GaAs reveal strong light emission at 1.3-1.6 μm, smooth surface with an average roughness below 2 nm and good rectifying I-V characteristics. Dark line defects are found in the QW. Post growth thermal annealing further improves the luminescence efficiency but does not remove those dark line defects. Some challenges of epitaxial growth using this method for laser applications are discussed. © 2006 Elsevier B.V. All rights reserved.
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