| 61. |
- Kaiser, M., et al.
(författare)
-
Polycrystalline SiC as source material for the growth of fluorescent SiC layers
- 2013
-
Ingår i: Silicon Carbide And Related Materials 2012. - : Trans Tech Publications Inc.. - 9783037856246 ; , s. 39-42
-
Konferensbidrag (refereegranskat)abstract
- Polycrystalline doped SiC act as source for fluorescent SiC. We have studied the growth of individual grains with different polytypes in the source material. We show an evolution and orientation of grains of different polytypes in polycrystalline SiC ingots grown by the Physical Vapor Transport method. The grain influence on the growth rate of fluorescent SiC layers grown by a sublimation epitaxial process is discussed in respect of surface kinetics.
|
|
| 62. |
- Kakanakova-Georgieva, Anelia, 1970-, et al.
(författare)
-
Behavior of background impurities in thick 4H-SiC epitaxial layers
- 2001
-
Ingår i: Appl. Surf. Sci., Vol. 184. ; , s. 242-246
-
Konferensbidrag (refereegranskat)abstract
- Behavior of background impurities in 4H-SiC layers is studied in terms of several growth process parameters. The layers were produced by sublimation epitaxy in Ta and Hf, as well as in graphite growth cell environment. Cathodoluminescence imaging and spectroscopy of cleaved samples demonstrate the impurity - thickness uniformity along thick (40-260 µm) layers. The effect of the Ta and Hf environment on the levels of residual impurities is considered through calculations of cohesive energies of Ta-X and Hf-X diatomic molecules and comparing them with those obtained for N-, Al- and B-containing vapor molecules. © 2001 Elsevier Science B.V. All rights reserved.
|
|
| 63. |
- Kakanakova-Georgieva, Anelia, 1970-, et al.
(författare)
-
Cathodoluminescence identification of donor-acceptor related emissions in as-grown 4H-SiC layers
- 2002
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 91:5, s. 2890-2895
-
Tidskriftsartikel (refereegranskat)abstract
- A comparative analysis of cathodoluminescence spectra in 4H-SiC layers with different N, Al, and B content is reported. The layers were produced by sublimation epitaxy and residual impurity concentrations were determined by secondary ion mass spectrometry. Epilayers doped with B in a wide concentration range, 5x10(15)-3x10(18) cm(-3), were achieved. Evidence of N, Al, and B related emissions by cathodoluminescence experiments is presented. Differences in the luminescence emitted by the layers are established that are attributed to different B content and impurity cooperation. The characteristics of broad green emission, originating from B-related centers, at 4.6 K, 300 K, as well as in high temperature annealed layers are discussed. The experimental results suggest that boron is involved in more than one deep acceptor center.
|
|
| 64. |
- Kakanakova-Georgieva, Anelia, 1970-, et al.
(författare)
-
Characteristics of boron in 4H-SiC layers produced by high-temperature techniques
- 2002
-
Ingår i: Materials Science Forum, Vols. 389-393. ; , s. 259-262
-
Konferensbidrag (refereegranskat)abstract
- Characteristics of boron in as-grown 4H-SiC layers produced by fast epitaxy, i.e. sublimation and vertical hot-wall CVD, were studied by electrical and optical measurements. The boron-related contribution to the net acceptor concentration in the layers (as determined by CV on p-type residual doped sublimation epitaxy layers), the presence of deep boron centers (as indicated by DLTS) and boron-related "green" emission at similar to 505 nm (as observed by CL) are detected for various growth temperatures and C/Si ratios. The results are discussed in relation with the C vacancies in the lattice that may be affected by growth rate and input C/Si ratio in the CVD process.
|
|
| 65. |
- Kakanakova-Georgieva, Anelia, 1970-, et al.
(författare)
-
Kinetics of residual doping in 4H-SiC epitaxial layers grown in vacuum
- 2002
-
Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 240:04-mar, s. 501-507
-
Tidskriftsartikel (refereegranskat)abstract
- Investigation on residual Al, B, and N co-doping of 4H-SiC epitaxial layers is reported. The layers were produced by sublimation epitaxy in Ta growth cell environment at different growth temperatures and characterized by secondary ion mass spectrometry. The vapor interaction with Ta was considered through calculations of cohesive energies of several Si-, Al-, B-, and N-containing vapor molecules and also of diatomic Ta-X molecules. An analysis of kinetic mechanisms responsible for impurity incorporation is performed. Among residuals, B exhibits a stronger incorporation dependence on temperature and growth at lower temperatures can favor B decrease in the layers. Under the growth conditions in this study (Ta environment and presence of attendant Al and N), B incorporation is assisted by Si2C vapor molecule. Boron tends to occupy carbon sites at higher temperatures, i.e. higher growth rates.
|
|
| 66. |
- Kakanakova-Georgieva, Anelia, 1970-, et al.
(författare)
-
Structural properties of 6H-SiC epilayers grown by two different techniques
- 1997
-
Ingår i: Materials Science and Engineering B. - 0921-5107. ; 46:1-3, s. 345-348
-
Tidskriftsartikel (refereegranskat)abstract
- In the present work we investigated the structural properties of 6H-SiC homoepitaxial layers utilizing microhardness and X-ray characterization techniques. The growth was performed by chemical vapour deposition (CVD) and liquid phase epitaxy (LPE) under various growth conditions. The depth Knoop hardness profiles represent decreasing curves due to the indentation size effect. With load increasing the curves saturate reaching microhardness values comparable with the known Vickers ones. At about 0.4 μm beneath the layer surfaces the curves show small plateaus which may be attributed to structural inhomogeneity. This is suggested by X-ray diffraction spectra taken from the same samples, which contain additional peaks besides the typical ones for 6H-SiC.
|
|
| 67. |
|
|
| 68. |
- Kamiyama, Satoshi, et al.
(författare)
-
Fluorescent SiC and its application to white light-emitting diodes
- 2011
-
Ingår i: Journal of semiconductors. - : IOP Publishing. - 1674-4926. ; 32:1, s. 013004-1-013004-3
-
Tidskriftsartikel (refereegranskat)abstract
- Fluorescent-SiC (f-SiC), which contains donor and acceptor impurities with optimum concentrations, has high conversion efficiency from NUV to visible light caused by donor-acceptor-pair (DAP) recombination. This material can be used as a substrate for a near UV light-emitting diode (LED) stack, and leads to monolithic white LED device with suitable spectral property for general lighting applications. In this paper, we describe basic technologies of the white LED, such as optical properties of f-SiC substrate, and epitaxial growth of NUV stack on the f-SiC substrate.
|
|
| 69. |
- Kamiyama, Satoshi, et al.
(författare)
-
White light-emitting diode based on fluorescent SiC
- 2012
-
Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 522, s. 23-25
-
Tidskriftsartikel (refereegranskat)abstract
- A monolithic white light-emitting diode (LED,) comprising a combination of a fluorescent-SiC (f-SiC) substrate and a nitride-based near-UV LED stack, is proposed. On the basis of the recombination of donor and acceptor pairs, the f-SiC substrate works as a phosphor for visible light emission. By employing the Fast Sublimation Growth Process method, the high-quality f-SiC substrate doped with N and B exhibited a nonradiative carrier lifetime of 55 mu s and an internal quantum efficiency (IQE) of 40%. With increasing donor and acceptor doping concentrations, a high IQE was estimated even at a high excitation level.
|
|
| 70. |
- Karlsson, M., et al.
(författare)
-
Wafer-scale epitaxial graphene on SiC for sensing applications
- 2015
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE - The International Society for Optics and Photonics. - 9781628418903
-
Konferensbidrag (refereegranskat)abstract
- The epitaxial graphene-on-silicon carbide (SiC-G) has advantages of high quality and large area coverage owing to a natural interface between graphene and SiC substrate with dimension up to 100 mm. It enables cost effective and reliable solutions for bridging the graphene-based sensors/devices from lab to industrial applications and commercialization. In this work, the structural, optical and electrical properties of wafer-scale graphene grown on 2'™'™ 4H semi-insulating (SI) SiC utilizing sublimation process were systemically investigated with focus on evaluation of the graphene'™s uniformity across the wafer. As proof of concept, two types of glucose sensors based on SiC-G/Nafion/Glucose-oxidase (GOx) and SiC-G/Nafion/Chitosan/GOx were fabricated and their electrochemical properties were characterized by cyclic voltammetry (CV) measurements. In addition, a few similar glucose sensors based on graphene by chemical synthesis using modified Hummer'™s method were also fabricated for comparison.
|
|
