Speaker
Ms
Thabsile Thabethe
(University of pretoria)
Description
Tungsten (W) thin film was deposited on bulk single crystalline 6H-SiC substrate and annealed in H2 and Ar ambient at temperatures ranging from 700 to 1000 ºC for 1 hour. The resulting solid-state reactions, phase composition and surface morphology were investigated by Rutherford backscattering spectroscopy (RBS), grazing incidence X-ray diffraction (GIXRD) and scanning electron microscopy (SEM) analysis techniques. As-deposited RBS results indicate the presence of W and O2 in the deposited thin film, the XRD showed the presence of W, WO3, W5Si3 and WC. RBS results indicated the interaction between W and SiC accompanied by the removal of oxygen at 700 ºC for the samples annealed in H2 ambient. The XRD analysis indicated the presences of W5Si3 and WC in the samples annealed at 700 ºC. At temperatures of 800 ºC, 900 ºC and 1000 ºC, W further reacted with the SiC substrate and formed mixed layer containing silicide phases and a carbide phase. That is, W5Si3, WSi2 and WC for the Ar ambient and W5Si3, WSi2, WC and W2C for H2 ambient. The SEM micrographs of the as-deposited samples indicated the W thin film had a uniform surface with small grains. Annealing at 800ºC led to the agglomeration of W grains into clusters for the H2 annealed samples. SEM micrographs of the Ar annealed samples at 800 ºC indicated randomly orientated large crystals growing on top of each other on the surface.
Primary author
Ms
Thabsile Thabethe
(University of pretoria)
Co-authors
Dr
Eric Njoronge
(University of pretoria)
Dr
Thulani Hlatshwayo
(University of Pretoria)
Mr
Tshepo Ntsoane
(Nuclear Energy Corporation of South Africa (NECSA))
