Berlin 2008 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 13: Dielectric and ferroelectric thin films and nanostructures III

DF 13.6: Vortrag

Donnerstag, 28. Februar 2008, 15:40–16:00, EB 107

Growth of HfO_x thin films by reactive molecular beam epitaxy — •Erwin Hildebrandt, Jose Kurian, and Lambert Alff — Institut für Materialwissenschaft, TU Darmstadt

Thin films of hafnium oxide were grown on single crystal r-cut and c-cut sapphire by reactive molecular beam epitaxy. The conditions for the growth of single oriented hafnium oxide thin films have been established. Hafnium oxide thin films were characterized by x-ray diffraction and optical absorption measurements. It was found that hafnium oxide thin films grown on r-cut sapphire were (00l) oriented whereas, on c-cut sapphire, hafnium oxide films showed different orientations depending on the growth temperature and oxidation conditions. The hafnium oxide films grown at higher temperature and under strong oxidation conditions yielded (00l) oriented films on c-cut sapphire whereas slightly weaker oxidation condition leads to (111) oriented hafnium oxide films. The bandgap deducted from optical absorption measurement carried out on hafnium oxide films grown under optimized conditions agreed well with the values reported in literature. A range of oxygen deficient thin films of hafnium oxide were also grown on single crystal sapphire substrates in order to investigate the effect of oxygen vacancies on dielectric properties of hafnium oxide. The oxygen deficient thin films of hafnium oxide show a decrease in bandgap with increase in oxygen deficiency.