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- Henry, Anne, et al.
(author)
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Determination of nitrogen doping concentration in doped 4H-SiC epilayers by low temperature photoluminescence
- 2005
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In: Physica Scripta. - 0031-8949 .- 1402-4896. ; 72:2-3, s. 254-257
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Journal article (peer-reviewed)abstract
- A complete calibration of nitrogen concentration in doped 4H-SiC material is presented. This is done in the very large range of doping available today, i.e. from low 1014 to 1019 cm-3. The samples are 4H-SiC films fabricated by hot-wall chemical vapour deposition. Low temperature photoluminescence is used as the experimental tool. For doping concentrations less than 8 × 1017 cm-3 comparison between the intensity of various luminescence lines is used, whereas for doping higher than 3 × 1018 cm-3 the energy position of an observed broad band allows the determination of the doping level.
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- Kakanakova-Georgieva, Anelia, 1970-, et al.
(author)
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Uniform hot-wall MOCVD epitaxial growth of 2 inch AlGaN/GaN HEMT structures
- 2007
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In: Journal of Crystal Growth, Vol. 300. - : Elsevier BV. - 0022-0248. ; , s. 100-103
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Conference paper (peer-reviewed)abstract
- The hot-wall metalorganic chemical vapor deposition (MOCVD) concept has been applied to the growth of AlxGa1-xN/GaN high electron mobility transistor (HEMT) device heterostructures on 2 inch 4H-SiC wafers. Due to the small vertical and horizontal temperature gradients inherent to the hot-wall MOCVD concept the variations of all properties of a typical HEMT heterostructure are very small over the wafer: GaN buffer layer thickness of 1.83 μm±1%, Al content of the AlxGa1-xN barrier of 27.7±0.1%, AlxGa1-xN barrier thickness of 25 nm±4%, sheet carrier density of 1.05×1013 cm-2±4%, pinch-off voltage of -5.3 V±3%, and sheet resistance of 449 Ω±1%.
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- Syväjärvi, Mikael, 1968-, et al.
(author)
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A surface study of wet etched AlGaN epilayers grown by hot-wall MOCVD
- 2007
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In: Journal of Crystal Growth, Vol. 300. - : Elsevier BV. - 0022-0248. ; , s. 242-245
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Conference paper (peer-reviewed)abstract
- Epitaxial layers of AlGaN were grown by hot-wall MOCVD and their surfaces wet chemically etched with phosphorous acid. The as-grown surfaces and the development of the etched surfaces after 10 and 20 min of etching were studied with atomic force microscopy (AFM) and CL. In the as-grown layers growth features may be resolved while the RMS is as low as 1.4 Å in a scan area of 2×2 μm. Surfaces etched for 10 min had developed etch pits and a low RMS roughness of 7 Å indicating a uniform quality of the layers. Micrometer scale hexagonal features were observed after 20 min of etching. In some cases a deep hexagonal etch pit is observed in the centre of the hexagonal feature with a 30° rotation to each other, suggesting that the origin is substrate-induced defects. © 2006 Elsevier B.V. All rights reserved.
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