Structural and band gaps studies of novel Al2-xHfxO3 materials toward MOS applications

Developments of new materials for MOS applications are important due to the problems of downscaling of SiO2. In this work, Hf doped Al2O3 materials were studied as a possible new material for use in metal oxide semiconductor (MOS) application. Novel Al2-xHfxO3 (x = 0.001, 0.002 and 0.003) materials were prepared by a self-propagating combustion synthesis method. X-Ray diffraction (XRD) results showed that all samples were pure with hexagonal crystal structure. Quantitative analysis via Rietveld refinements showed that Hf was successfully substituted in the hexagonal Al2O3 crystal structure. The Hf content was confirmed via energy dispersive X-Ray spectroscopy (EDS). UV-visible spectroscopy showed that Al2-xHfxO3 materials exhibited band gap narrowing with respect to pure Al2O3 materials and it is dependent on the Hf content following an exponential function.