| 1. |
- Siegert, Jörg, et al.
(författare)
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Recombination properties of Si-doped InGaAs/GaAs quantum dots
- 2006
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 17:21, s. 5373-5377
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Tidskriftsartikel (refereegranskat)abstract
- The recombination properties of directly doped InGaAs/GaAs quantum dots (QDs) for application in quantum dot infrared photodetectors (QDIPs) have been investigated by time-resolved photoluminescence. Compared with undoped and barrier-doped samples, the overall effect of direct dot doping is found to be small, resulting in only slight deterioration of dot homogeneity. Low-temperature photoluminescence decay times decrease very little, indicating that direct doping does not cause a significant increase of nonradiative recombination. In addition, directly doped quantum dots show a significantly weaker quenching of the photoluminescence intensity with temperature. At the same time, barrier doping causes the formation of more and smaller dots, which results in high photoluminescence intensity at low temperatures but an early onset of thermal carrier emission from the dots. The results suggest that direct QD doping is more prospective for realizing room-temperature operation in QDIPs.
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| 2. |
- Slotte, J., et al.
(författare)
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Fluence, flux, and implantation temperature dependence of ion-implantation-induced defect production in 4H-SiC
- 2005
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 97:3
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Tidskriftsartikel (refereegranskat)abstract
- Vacancy-type defect production in Al- and Si-implanted 4H-SiC has been studied as a function of ion fluence, ion flux, and implantation temperature in the projected ion range region by positron annihilation spectroscopy and Rutherford backscattering techniques. Ion channeling measurements show that the concentration of displaced silicon atoms increases rapidly with increasing ion fluence. In the ion fluence interval of 10(13)-10(14) cm(-2) the positron annihilation parameters are roughly constant at a defect level tentatively associated with the divacancy VCVSi. Above the ion fluence of 10(14) cm(-2) larger vacancy clusters are formed. For implantations as a function of ion flux (cm(-2) s(-1)), ion channeling and positron annihilation measurements behave similarly, i.e., indicating increasing damage in the projected range region with increasing ion flux. However, for samples implanted at different temperatures the positron annihilation parameter S shows a clear minimum at approximately 100 degreesC, whereas the normalized backscattering yield decrease continuously with increasing implantation temperature. This is explained by the formation of larger vacancy clusters when the implantation temperature is increased.
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| 3. |
- Svensson, B.G., et al.
(författare)
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Ion implantation processing and related effects in SiC
- 2006
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Ingår i: Silicon Carbide and Related Materials 2005, Pts 1 and 2. - 9780878494255 ; , s. 781-786
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Konferensbidrag (refereegranskat)abstract
- A brief survey is given of some recent progress regarding ion implantation processing and related effects in 4H- and 6H-SiC. Four topics are discussed; an empirical ion range distribution simulator, dynamic defect annealing during implantation, formation of highly p(+)-doped layers, and deactivation of N donors by ion-induced defects.
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| 4. |
- Wong-Leung, J., et al.
(författare)
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Ion implantation in 4H-SiC
- 2008
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 266:8, s. 1367-1372
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Tidskriftsartikel (refereegranskat)abstract
- Silicon carbide offers unique applications as a wide bandgap semiconductor. This paper reviews various aspects of ion implantation in 4H-SiC studied with a view to optimise ion implantation in silicon carbide. Al, P and Si ions with keV energies were used. Channelling effects were studied in both a-axis and c-axis crystals as a function of tilts along major orthogonal planes and off the major orthogonal planes. Major axes such as [0 0 0 1] and the [ 1 1 (2) over bar 0] and minor axis like the [1 1 (2) over bar 3] showed long channelling tails and optimum tilts for minimising channelling are recommended. TEM analyses of the samples showed the formation of (0 0 0 1) prismatic loops and the (1 1 (2) over bar 0) loops as well,in both a and c-cut crystals. We also note the presence of voids only in P implanted samples implanted with amorphising doses. The competing process between damage accumulation and dynamic annealing was studied by determining the critical temperature for the transition between crystalline and amorphous SiC and an activation energy of 1.3 eV is extracted.
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