| 1. |
- Lo, Ikai, et al.
(author)
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Anomalous k-dependent spin splitting in wurtzite AlxGa1-xN/GaN heterostructures
- 2007
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 75:24
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Journal article (peer-reviewed)abstract
- We have observed the k-dependent spin splitting in wurtzite AlxGa1-xN/GaN heterostructures. An anomalous beating pattern was observed in Shubnikov-de Haas measurements due to the interference of Rashba and Dresselhaus spin-orbit interactions. The dominant mechanism for the k-dependent spin splitting at high values of k is attributed to Dresselhaus term which is enhanced by the Delta(C1)-Delta(C3) coupling of wurtzite band folding effect. The interference of Rashba and Dresselhaus effects in the AlxGa1-xN/GaN heterostructure provides a potential candidate for the gate-controlled spin-polarized spintronic devices.
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| 2. |
- Lo, Ikai, et al.
(author)
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Study of two-subband population in Fe-doped AlxGa1-xN/GaN heterostructures by persistent photoconductivity effect
- 2006
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 74:24, s. 245325-
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Journal article (peer-reviewed)abstract
- The electronic properties of Fe-doped Al0.31Ga0.69N/GaN heterostructures have been studied by Shubnikov-de Haas measurement. The lowest two subbands of the two-dimensional electron gas in the heterointerface were populated. After the low temperature illumination, the electron density increases from 11.99x10(12) cm(-2) to 13.40x10(12) cm(-2) for the first subband and from 0.66x10(12) cm(-2) to 0.94x10(12) cm(-2) for the second subband. The persistent photoconductivity effect (similar to 13% increase) is mostly attributed to the Fe-related deep-donor level in GaN layer. The second subband starts to populate when the first subband is filled at a density of 9.40x10(12) cm(-2). We obtained the energy separation between the first and second subbands to be 105 meV.
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| 3. |
- Metaferia, Wondwosen, et al.
(author)
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Morphological evolution during epitaxial lateral overgrowth of indium phosphide on silicon
- 2011
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In: Journal of Crystal Growth. - : Elsevier. - 0022-0248 .- 1873-5002. ; 332:1, s. 27-33
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Journal article (peer-reviewed)abstract
- Epitaxial lateral overgrowth of InP from mesh and line openings on masked InP seed layer on Si(0 0 1) wafer is investigated. Coalescence occurred more rapidly from the mesh openings than from the line openings. Lethargic coalescence in the line openings is attributed to the gradual formation of growth retarding boundary planes in the initial stages of growth. Extended growth leads to complete coalescence in both types of openings. The surface roughness of the coalesced layer is inversely proportional to its thickness. Cathodoluminescence studies on the uncoalesced islands show the emergence of facets with orientation-dependent dopant concentration, but reveal no defects, in contrast to the coalesced regions. The latter are relaxed and their dislocation density deduced from panchromatic cathodoluminescence mapping varies from 6 x 10(6) to 4 x 10(7) cm(-2) depending on the layer thickness; the reduced density at higher thickness indicates partial self annihilation of dislocations. TEM cross-section studies show that most of the threading dislocations originating in the InP seed layer/Si interface are blocked by the mask, but new dislocations are generated. Some of these dislocations are associated with bounding planar defects such as stacking faults, possibly generated during lateral growth across the mask due to unevenness of the mask surface.
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