| 1. |
- Arnaudov, B, et al.
(författare)
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Modeling of the free-electron recombination band in emission spectra of highly conducting n-GaN
- 2001
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 64:4
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Tidskriftsartikel (refereegranskat)abstract
- We simulate the spectral distribution of the free-electron recombination band in optical emission spectra of GaN with a free-carrier concentration in the range of 5 x 10(17)-1 x 10(20) cm(-3). The influence of several factors, such as nonparabolicity, electron-electron interaction. and electron-impurity interaction on both the spectral and energy position and the effective gap narrowing are taken into account. The calculated properties of the free-electron-related emission bands are used to interpret the experimental photoluminescence and cathodoluminescence spectra of GaN epitaxial layers.
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| 2. |
- Gelhausen, O, et al.
(författare)
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Dissociation of H-related defect complexes in Mg-doped GaN
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 69:12
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Tidskriftsartikel (refereegranskat)abstract
- Post-growth annealing and electron beam irradiation during cathodoluminescence were used to determine the chemical origin of the main optical emission lines in moderately and heavily Mg-doped GaN. The 3.27 eV donor-acceptor pair (DAP) emission line that dominates the emission spectrum in moderately Mg-doped (p-type) GaN was found to be strongly reduced by electron irradiation and of different chemical origin than the DAP at a similar energetic position in Si-doped (n-type) GaN. These results suggest that the acceptor responsible for the 3.27 eV DAP emission in Mg-doped GaN is Mg,and that the donor (20-30 meV) is hydrogen-related, possibly a (V-N-H) complex. This complex is dissociated either by electron irradiation or thermal annealing in N-2 or O-2 atmosphere. We found that upon electron irradiation, a deeper emission line (centered at 3.14 eV) emerged, which was assigned to a DAP consisting of the same Mg acceptor level and a deeper donor (100-200 meV) with a similar capture cross section as the donor in the 3.27 eV emission. Moreover, two different deep donor levels at 350+/-30 and 440+/-40 meV were identified as being responsible for,the blue band (2.8-3.0 eV) in heavily Mg-doped GaN. The donor level at 350+/-30 meV was strongly affected by electron irradiation and attributed to a H-related defect.
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| 3. |
- Godlewski, M, et al.
(författare)
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Compensation mechanisms in magnesium doped GaN
- 2004
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Ingår i: Physica status solidi. A, Applied research. - : Wiley. - 0031-8965 .- 1521-396X. ; 201:2, s. 216-220
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Tidskriftsartikel (refereegranskat)abstract
- Compensation processes in magnesium doped GaN epilayers and bulk samples are studied. We demonstrate enhancement of potential fluctuations in Mg doped samples, from Kelvin probe atomic force microscopy measurements. Large- and small-scale light emission fluctuations are also demonstrated. Micro-photoluminescence (PL) study indicates an unusual anti-correlation between the intensities of excitonic and defect-related emission processes in p-type doped structures and also the presence of the so-called hot-PL. Hot-PL observed in compensated p-type samples, we relate to the presence of strong potential fluctuations. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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| 4. |
- Goldys, EM, et al.
(författare)
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Characterization of red emission in nominally undoped hydride vapor phase epitaxy GaN
- 2001
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Ingår i: MRS Internet Journal of Nitride Semiconductor Research. - 1092-5783. ; 6:1, s. art. no.-1
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Tidskriftsartikel (refereegranskat)abstract
- We report characterization of the red emission band in hydride vapor phase epitaxial GaN using cathodoluminescence spectroscopy and imaging and time-resolved photoluminescence. The observed properties of the emission are consistent with recombination of excitons bound at close donor-acceptor pairs. The time evolution of the emission signal during electron beam irradiation supports the association of the red emission with charged centres.
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| 5. |
- Paskova, Tanja, et al.
(författare)
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Mass transport growth and properties of hydride vapour phase epitaxy GaN
- 2001
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Ingår i: Physica status solidi. A, Applied research. - 0031-8965 .- 1521-396X. ; 188:1, s. 447-451
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Tidskriftsartikel (refereegranskat)abstract
- We report a comparative study of the optical and structural properties of mass-transport and conventionally grown GaN by hydride vapor phase epitaxy. A strong donor-acceptor pair emission is observed from the mass-transport regions with a distinctive intensity contrast between the exciton and donor-acceptor bands from mass-transport and nontransport regions. Secondary ion mass spectroscopy was employed to investigate the impurity incorporation into different regions. A moderate increase of residual impurity incorporation or redistribution was found in mass-transport regions related to different growth modes.
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