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| 2. |
- 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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| 3. |
- Song, Yuxin, 1981, et al.
(författare)
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Enhancement of optical quality in metamorphic quantum wells using dilute nitride buffers
- 2010
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 97:9, s. 091903-
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Tidskriftsartikel (refereegranskat)abstract
- Strong enhancement of optical quality in quantum wells by incorporating nitrogen in metamorphic InGaAs buffers grown on GaAs substrates is demonstrated. This has resulted in 3.7 or 5.4 times enhancement of photoluminescence intensity from the metamorphic quantum wells when using dilute nitride superlattice alone or adding nitrogen in a strain compensated GaAs/In0.3Al0.7As superlattice, respectively. This study shows great potentials by incorporating N in metamorphic buffers to further improve the quality of metamorphic optoelectronic devices.
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| 4. |
- Song, Yuxin, 1981, et al.
(författare)
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Investigation of metamorphic InGaAs quantum wells using N-incorporated buffer on GaAs grown by MBE
- 2011
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 323:1, s. 21-25
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Tidskriftsartikel (refereegranskat)abstract
- Strong enhancement of photoluminescence intensity from InGaAs quantum wells by incorporating nitrogen in metamorphic InGaAs buffers grown on GaAs substrates was demonstrated and investigated. The enhancement of photoluminescence intensity is found to be from both the weak strain effect and the strong lattice hardening effect, indicating blocking effect of threading dislocations due to the N incorporation. Combination of this method with a strain compensated superlattice was proved to be effective in obtaining good quality metamorphic InGaAs quantum wells.
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| 5. |
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| 6. |
- 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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| 8. |
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| 9. |
- Tångring, Ivar, 1978, et al.
(författare)
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Manipulation of strain relaxation in metamorphic heterostructures
- 2007
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Ingår i: Applied Physics Letters. ; 90, s. 071904-
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Tidskriftsartikel (refereegranskat)abstract
- The authors have discovered that high doping densities in an alloy graded InGaAs buffer havedramatic effects on strain relaxation dynamics and consequently surface and optical qualities inmetamorphic heterostructures. Compared with undoped graded buffers, the use of Be dopingsignificantly improves structural, surface, and optical qualities while the use of Si dopingdeteriorates all these properties. This discovery is significant for the realization of metamorphicoptoelectronic devices.
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| 10. |
- Tångring, Ivar, 1978, et al.
(författare)
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Metamorphic growth of 1.25 – 1.29 µm InGaAs quantum well lasers by molecular beam epitaxy
- 2007
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 301:SPEC. ISS., s. 971-974
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate 1.25–1.29 μm metamorphic laser diodes grown on GaAs by molecular beam epitaxy (MBE) using an alloy-graded buffer layer (GBL). Use of Be in the GBL is effective to reduce surface/interface roughness and improves optical quality. The RMS surface roughness of the optimized metamorphic laser is only two atomic monolayers for 1×1 μm2. Cross-sectional transmission electron microscopy (TEM) images confirm that most dislocations are blocked in the GBL. Ridge waveguide lasers with 4 μm wide ridge were fabricated and characterized. The average threshold current under the pulsed excitation is in 170–200 mA for a cavity length of 0.9–1.5 mm. This value can be further reduced to about 100 mA by high-reflectivity coating. Lasers can work in an ambient temperature up to at least 50 °C.
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