| 1. |
- Gelczuk, L., et al.
(författare)
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Bi-induced acceptor level responsible for partial compensation of native free electron density in InP1-xBix dilute bismide alloys
- 2016
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Ingår i: Journal of Physics D: Applied Physics. - : IOP Publishing. - 1361-6463 .- 0022-3727. ; 49:11
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Tidskriftsartikel (refereegranskat)abstract
- Deep level transient spectroscopy (DLTS) has been applied to study electron and hole traps in InPBi alloys with 2.2 and 2.4% Bi grown by molecular beam epitaxy. One donor-like trap with the activation energy of 0.45-0.47 eV and one acceptor-like trap with activation energy of 0.08 eV have been identified in DLTS measurements. For the reference sample (InP grown at the same temperature), the deep donor trap has also been observed, while the acceptor trap was not detected. According to the literature, the deep donor level found in InP(Bi) at 0.45-0.47 eV below the conduction band has been attributed to the isolated P-In defect, while the second trap, which is observed only for Bi containing samples at 0.08 eV above the valence band can be attributed to Bi clusters in InPBi. This acceptor level was proposed to be responsible for the observed partial compensation of native free electron density in InPBi layers. It is also shown that the deep donor traps are active in photoluminescence (PL). A strong radiative recombination between donor traps and the valence band are observed in PL spectra at energy 0.6-0.8 eV, i.e. similar to 0.47 eV below the energy gap of InPBi, which is determined by contactless electroreflectance.
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| 2. |
- Krammel, C. M., et al.
(författare)
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Incorporation of Bi atoms in InP studied at the atomic scale by cross-sectional scanning tunneling microscopy
- 2017
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Ingår i: Physical Review Materials. - 2475-9953. ; 1:3
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Tidskriftsartikel (refereegranskat)abstract
- We show the potential of cross-sectional scanning tunneling microscopy to address structural properties of dilute III-V bismides by investigating Bi:InP. Bismuth atoms down to the second monolayer below the {110} InP surfaces, which give rise to three classes of distinct contrast, are identified with the help of density functional theory calculations. Based on this classification, the pair-correlation function is used to quantify the ordering of Bi atoms on the long range. In a complementary short-ranged study, we investigate the Bi ordering at the atomic level. An enhanced tendency for the formation of first-nearest-neighbor Bi pairs is found. In addition, the formation of small Bi clusters is observed whose geometries appear to be related to strong first-nearest-neighbor Bi pairing. We also identify growth related crystal defects, such as In vacancies, P antisites, and Bi antisites.
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| 3. |
- Pan, W. W., et al.
(författare)
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Growth and material properties of InPBi thin films using gas source molecular beam epitaxy
- 2016
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388. ; 656, s. 777-783
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Tidskriftsartikel (refereegranskat)abstract
- The effects of Bi, In flux and PH3 pressure on Bi incorporation, structural and transport properties of InPBi grown by gas source molecular beam epitaxy have been systematically studied. Incorporation of Bi behaves like a dopant and its content increases linearly with Bi flux and inversely with the InP growth rate (In flux), and is independent of the PH3 pressure studied. High PH3 pressure causes rough surface and introduction of Bi improves surface quality. Intrinsic InP grown at a low temperature reveals n-type due to the P-ln antisite defects and the electron density is proportional to the PH3 pressure and inversely proportional to the InP growth rate. Incorporation of Bi induces p-type dopant that compensates the background electron concentration but doesn't degrade the electron mobility for the Bi content up to 2.4%. These results suggest that there is still a large room left to optimize material quality and maximize Bi incorporation in InPBi using gas source molecular beam epitaxy.
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| 4. |
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| 5. |
- Zhang, L, et al.
(författare)
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Nanoscale Distribution of Bismuth in InPBi
- 2015
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Ingår i: 6th International Workshop on Bismuth Containing Semiconductors, Madison, USA, July 19th-22nd, 2015.
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Konferensbidrag (refereegranskat)
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| 6. |
- Zhang, L, et al.
(författare)
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Nanoscale Distribution of Bismuth in InPBi
- 2016
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Ingår i: International Conference on Semiconductor Mid-IR Materials and Optics (SMMO) 2016, Lisbon, Portugal, March 21-24, 2016.
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Konferensbidrag (refereegranskat)
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| 7. |
- Gu, Yi, et al.
(författare)
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Structural and optical characterizations of InPBi thin films grown by molecular beam epitaxy
- 2014
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Ingår i: Nanoscale Research Letters. - 1556-276X .- 1931-7573. ; 9:24
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Tidskriftsartikel (refereegranskat)abstract
- InPBi thin films have been grown on InP by gas source molecular beam epitaxy. A maximum Bi composition of 2.4% is determined by Rutherford backscattering spectrometry. X-ray diffraction measurements show good structural quality for Bi composition up to 1.4% and a partially relaxed structure for higher Bi contents. The bandgap was measured by optical absorption, and the bandgap reduction caused by the Bi incorporation was estimated to be about 56 meV/Bi%. Strong and broad photoluminescence signals were observed at room temperature for samples with xBi
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| 8. |
- Krammel, C. M., et al.
(författare)
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Probing the local electronic structure of isovalent Bi atoms in InP
- 2020
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Ingår i: Physical Review B. - 2469-9969 .- 2469-9950. ; 101:2
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Tidskriftsartikel (refereegranskat)abstract
- Cross-sectional scanning tunneling microscopy (X-STM) is used to experimentally study the influence of isovalent Bi atoms on the electronic structure of InP. We map the spatial pattern of the Bi impurity state, which originates from Bi atoms down to the sixth layer below the surface, in topographic, filled-state X-STM images on the natural {110} cleavage planes. The Bi impurity state has a highly anisotropic bowtielike structure and extends over several lattice sites. These Bi-induced charge redistributions extend along the < 110 > directions, which define the bowtielike structures we observe. Local tight-binding calculations reproduce the experimentally observed spatial structure of the Bi impurity state. In addition, the influence of the Bi atoms on the electronic structure is investigated in scanning tunneling spectroscopy measurements. These measurements show that Bi induces a resonant state in the valence band, which shifts the band edge toward higher energies. Furthermore, we show that the energetic position of the Bi-induced resonance and its influence on the onset of the valence band edge depend crucially on the position of the Bi atoms relative to the cleavage plane.
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| 9. |
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| 10. |
- Wang, K., et al.
(författare)
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InPBi Single Crystals Grown by Molecular Beam Epitaxy
- 2014
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- InPBi was predicted to be the most robust infrared optoelectronic material but also the most difficult to synthesize within In-VBi (V 5 P, As and Sb) 25 years ago. We report the first successful growth of InPBi single crystals with Bi concentration far beyond the doping level by gas source molecular beam epitaxy. The InPBi thin films reveal excellent surface, structural and optical qualities making it a promising new III-V compound family member for heterostructures. The Bi concentration is found to be 2.4 +/- 0.4% with 94 +/- 5% Bi atoms at substitutional sites. Optical absorption indicates a band gap of 1.23 eV at room temperature while photoluminescence shows unexpectedly strong and broad light emission at 1.4-2.7 mmwhich can't be explained by the existing theory.
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