Nicolau Molina Bom

Enhancement in interface robustness regarding thermal oxidation in nanostructured Al2O3 deposited on 4H-SiC

Experimental evidences of enhanced stability of Al2O3/SiC structures following thermal annealing are presented. 5- and 40-nm-thick Al2O3 films evaporated on the Si- and C-terminated faces of 4H-SiC were annealed up to 1000 °C in different atmospheres, leading to crystallization and densification of Al2O3, with an increase in the band gap. Exposure to O2 at high temperatures produced SiO2 and AlSixOy at the Al2O3/SiC interface, with less silicate on the Si-terminated face. Annealing in N2 before exposure to O2 hindered oxygen diffusion and exchange, leading to more stable thin film structures from the point of view of atomic transport.

GeO2/Ge structure submitted to annealing in deuterium : incorporation pathways and associated oxide modifications

Deuterium (D) incorporation in GeO2/Ge structures following D2 annealing was investigated. Higher D concentrations were obtained for GeO2/Ge samples in comparison to their SiO2/Si counterparts annealed in the same conditions. Oxygen vacancies produced during the annealing step in D2 constitute defect sites for D incorporation, analogous to defects at the SiO2/Si interfacial region. Besides D incorporation, volatilization of the oxide layer is also observed as a consequence of D2 annealing, especially in the high temperature regime of the present study (>450 °C). In parallel to this volatilization, the stoichiometry and chemical structure of remnant oxide are modified as well. These results evidence the broader impact of forming gas annealing in dielectric/Ge structures with respect to SiO2/Si counterparts.