| 1. |
- 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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| 2. |
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| 3. |
- Song, Yuxin, 1981, et al.
(författare)
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Effects of doping and grading slope on surface and structure of metamorphic InGaAs buffers on GaAs substrates
- 2009
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 106:12, s. 123531-
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the effects of doping and grading slope on the surface and structure of linearly alloy graded InGaAs buffers. It is found that the Be doping can improve material properties, resulting in smaller surface roughness and a lower threading dislocation density, while the Si doping has an opposite effect. The effect is strongly dependent on the grading slope. A moderate In grading slope is preferable for the strain relaxation and the minimization of the negative effect of Si doping. Physical mechanisms are proposed to explain the experimental observations. Since doping is essential for many types of optoelectronic devices, these results are valuable for improving the material properties and performance of metamorphic devices.
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| 4. |
- Tångring, Ivar, 1978, et al.
(författare)
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A study of the doping influence on strain relaxation of graded composition InGaAs layers grown by molecular beam epitaxy
- 2009
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Ingår i: Journal of Crystal Growth. - 0022-0248. ; 311, s. 1684-
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the role of p- and n-type doping in strain relaxation of graded composition InGaAs layers grown by molecular beam epitaxy. It is found that p-type Be-doping can improve material properties, resulting in smaller surface roughness and lower threading dislocation density, while n-type Si-doping has an opposite effect. The effect is strongly dependent on the grading profile, with linear grading showing small differences, while there is a significant difference when an exponential grading is used. Since doping is essential for many types of devices, these results are useful for improving the material properties and performance of metamorphic devices.
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| 5. |
- Tångring, Ivar, 1978, et al.
(författare)
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Metamorphic InGaAs telecom lasers on GaAs
- 2009
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819474766 ; Proc. SPIE 7230, s. 723003-
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Konferensbidrag (refereegranskat)abstract
- We demonstrate GaAs-based metamorphic lasers in the 1.3-1.55 μm telecom range grown by molecular beam epitaxy.The introduction of dopants in a compositionally graded layer is shown to significantly influence material properties, aswell as having impact on the laser device design. Investigating and understanding of strain relaxation and dislocationdynamics is useful for improving material quality, performance and robustness of metamorphic devices. We demonstratepulsed lasing up to 1.58 μm and continuous wave lasing at 1.3 μm at room temperature with low threshold currents.
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| 6. |
- Wang, Shu Min, 1963, et al.
(författare)
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Metamorphic InGaAs Materials and Telecom Lasers
- 2009
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Ingår i: International Conference on Materials and Advanced Technology (ICMAT) 2009, Singapore, June 28 - July 3, 2009. (invited paper).
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Konferensbidrag (refereegranskat)
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