| 31. |
- Song, Yuxin, 1981, et al.
(författare)
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Molecular beam epitaxy growth of InSb1-xBix thin films
- 2013
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 378, s. 323-328
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Tidskriftsartikel (refereegranskat)abstract
- Molecular beam epitaxy growth for InSb1-xBix thin films on (100) GaAs substrates is reported. Successful Bi incorporation for 2% is achieved, and up to 70% of the incorporated Bi atoms are at substitutional sites. The effects of growth parameters on Bi incorporation and surface morphology are studied. Strong In and Ga inter-diffusion induced by Bi incorporation is observed and discussed.
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| 32. |
- Song, Yuxin, 1981, et al.
(författare)
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Molecular Beam Epitaxy Growth of InSbxBi1-x
- 2011
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Ingår i: 2nd International Workshop on Bismuth-Containing Semiconductors: Theory, Simulation and Experiment, Guildford, UK.
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Konferensbidrag (refereegranskat)
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| 33. |
- Song, Yuxin, 1981, et al.
(författare)
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Natural patterning of templates on GaAs by formation of cracks
- 2015
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Ingår i: AIP Advances. - : AIP Publishing. - 2158-3226 .- 2158-3226. ; 5:6, s. Art Nr 067146-
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Tidskriftsartikel (refereegranskat)abstract
- Substrate pre-patterning is an effective way to overcome large lattice mismatch and suppress threading defects in the growth of heterostructures. In this work, a new concept was proposed to form natural patterns on commercial substrates monolithically by the formation of surface cracks. Tensile strain was intentionally brought in with a GaAs or GaNAs layer above an InGaAs layer on GaAs substrates. Surface crack patterns successfully formed during the strain relaxation. The strain in a 1 μm buffer layer atop the pattern was found effectively relaxed. Detailed residual strain distribution was simulated by the finite element method.
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| 34. |
- Song, Yuxin, 1981
(författare)
-
Novel Materials and Technologies for IR Optoelectronic Applications
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis focuses on novel III-V materials (InAs/GaSb type-II superlattices, T2SL, and dilute bismides) and metamorphic growth techniques for infrared optoelectronics all of which may find wide spread applications in telecommunication, energy harvesting and saving, sensing and imaging. Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) photodetectors at the atmospheric windows of 3-5 and 8-12 µm, respectively, are currently dominated by HgCdTe and quantum well infrared photodetectors. These detectors, however, suffer from the suitability for making focal plane array (FPA) detectors due to the material non-uniformity or the low operation temperature that significantly increases the cost for a practical detection or imaging system. InAs/GaSb type-II superlattices are promising candidates for FPA detectors with better performance at a lower cost. Dilute bismides where a small amount of Bi atoms are incorporated into traditional host III-V semiconductors have theoretically shown a number of interesting physical properties. The large energy band bowing effect with retained transport and optical properties make these materials attractive for making short-wavelength infrared (SWIR), MWIR and LWIR optoelectronic devices. Dilute bismides have been only little studied among the III-V semiconductors, and in particular epitaxial growth of dilute III-SbBi is almost unexplored. Metamorphic growth is an efficient technique for lattice engineering and useful for device applications such as multi-junction solar cells, III-V and Si integration, electronic and optoelectronic devices on cheap substrates. Here, growth optimization and innovations to minimize threading dislocations are challenging and crucial for improving the material quality.The work in this thesis deals with issues related to the realization of these novel III-V materials and metamorphic growth techniques using molecular beam epitaxy (MBE). It is investigated how doping in alloy graded metamorphic buffers influences material quality and a new method to reduce dislocation density and improve optical quality by using dilute nitride buffer layers is demonstrated. Design and growth optimization of T2SL structures for mid-IR detectors are presented. MBE growth of novel dilute III-SbBi alloys is investigated. The growth of GaSbBi is reported for the first time. The abnormal lattice contraction of GaSbBi is discovered and explained.
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| 35. |
- Song, Yuxin, 1981
(författare)
-
Optimization of Metamorphic Materials on GaAs Grown by MBE
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Advanced epitaxial technologies such as molecular beam epitaxy (MBE) and metal-organic vapor phase epitaxy (MOVPE) have enabled the idea of semiconductor heterostructures, which built up the foundation of the fast developing information and communication technology nowadays. Lattice mismatch has been a problem limiting designs of semiconductor heterostructures. Restricted by the availability of large and high-quality commercial substrates, only a small range of materials with a lattice constant close to certain substrate, such as GaAs and InP, could be chosen. Metamorphic growth is one of the solutions by which a virtual substrate with a desired lattice constant can be obtained after growing a mismatched but nearly relaxed buffer layer on a conventional substrate. The main challenges of this method are the rough interface and a high threading dislocation (TD) density in the active region of the devices. The TD problem is more severe for optoelectronic devices, such as lasers, which have a large device area, and therefore can easily contain TDs in the active region. Although there have been notable progresses for metamorphic optoelectronic devices in recent years, further reduction of the TD density is still required to improve the performance and make them competitive with existing products. In this work, we investigate and optimize growth schemes of metamorphic buffer layers grown on GaAs substrate by MBE. Effects of both n- and p-type doping on material quality in alloy graded InGaAs buffers with different parameters, such as grading profiles, grading slopes, In compositions and thicknesses are studied systemically. Moreover, further TD reduction by nitrogen incorporation in metamorphic buffers is demonstrated. The physical origin is found to be due to both the strain and the lattice hardening effect. These results show that by proper designs of the metamorphic buffers there are great potentials to further improve the quality of metamorphic heterostructures and enhance the performance of metamorphic optoelectronic devices.
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| 36. |
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| 37. |
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| 38. |
- 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-
-
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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| 39. |
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| 40. |
- Tångring, Ivar, 1978, et al.
(författare)
-
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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