Electron spin resonance studies of transition metal deep level impurities in SiC.

By electron spin resonance (ESR) and photo-ESR, vanadium has been identified as an electrically amphoteric deep level impurity introducing both donor, Dhigh0/Dhighplus, and acceptor, Ahigh0/Ahighminus, states in the band gap of 4H- and 6H-SiC. The vanadium donor level in 6H-SiC has been located by photo-ESR near midgap, Esubv plus 1.6eV. Omnipresent titanium impurities were found to form complexes with nitrogen donors; the corresponding donor level of the (TiN) pair in 6H-SiC occurs at Esubc-0.6eV

Leistungs-Infrarotdioden aus Gallium-Aluminium-Arsenid Abschlussbericht

With 51 figs. und 32 refs.SIGLEDEGerman

Zuechtung und Charakterisierung von Siliziumkarbid-Einkristallen und Siliziumkarbid-Epitaxieschichten fuer die Anwendung in der Hochtemperatur-Elektronik und Sensorik Abschlussbericht

Due to its excellent physical properties, silicon carbide (SiC) appears especially suited as a material for high temperature and high power devices. At the start of the project, substrate fabrication as well as epitaxy processes both had a standing far removed from any commercial use. At that point scientific knowledge as regards defects, especially deep levels, was small. Therefore, work was carried out on the growth of bulk crystals and of single-crystal epitaxy layers. The materials produced were investigated using different physical methods (DLTS, polarisation microscopy, transmission spectroscopy, photoluminescence, Hall-measurements, RBS, ESR, ENDOR). Part of the necessary apparatus (DLTS, high resolution spectrometer) was built at the beginning of the project. During the running of the project the purity of the bulk crystals was improved, methods for reduction of macro-defects were worked out and knowledge about the doping process was increased. Due to the clearly higher purity of the layers and the fact that the layer thickness could be precisely controlled, the vapour phase epitaxy was preferable to the liquid phase epitaxy. The differing doping levels caused by different lattice sites were determined using temperature dependant Hall-measurements. Firstly, exact electrical measurements of the boron acceptor in 6H-SiC were carried out. Using EPR and ENDOR measurements a model of the boron defect could be set up. It was proved through optical measurements, MCDA and ODMR-spectra that vanadium is an important deep level for the recombination process. Progress was made in the area of SiC-specific technology, especially the 'dry-etching process' and oxidation. (orig.)SIGLEAvailable from TIB Hannover: F95B236+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman