ISSN:
1662-9752
Quelle:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Thema:
Maschinenbau
Notizen:
D-band electron paramagnetic resonance (EPR) measurements as well as X and Q-bandfield-swept Electron Spin Echo (ESE) and pulsed Electron Nuclear Double Resonance (ENDOR)studies were performed on a series of n-type 4H-SiC wafers grown by different techniques includingsublimation sandwich method (SSM), physical vapor transport (PVT) and modified Lelymethod. Depending on the C/Si ratio and the growth temperature the n-type 4H-SiC wafers revealed,besides a triplet due to nitrogen residing on the cubic site (Nc), two nitrogen (N) related EPRspectra with g||=2.0055, g⊥=2.0010 and g||=2.0063, g⊥=2.0005 with different intensities. In the sampleswith low C/Si ratio the EPR spectrum with g|| =2.0055, g⊥=2.0010 consists of a triplet with lowintensity which is tentatively explained as a N-related complex, while in the samples with high C/Siratio the triplet is transformed into one structureless line of high intensity, which is explained as beingdue to an exchange interaction between N donors. In the samples grown at low temperature withenhanced carbon concentration the EPR line with g||=2.0063, g⊥=2.0005 and a small hyperfine (hf)interaction dominates the EPR spectrum. It is attributed to N on the hexagonal lattice site. The interpretationof the EPR data is supported by activation energies and donor concentrations obtainedfrom Hall effect measurements for three donor levels in this series of 4H-SiC samples
Materialart:
Digitale Medien
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/17/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.556-557.355.pdf
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