Combining GeO2 passivation strategies aiming at dielectric layers with superior properties on germanium substrates

Abstract

Oxygen transport and incorporation in hafnium doped GeO₂ films (GeHf_xO_y) deposited on Ge were investigated. GeO desorption from GeO₂/Ge was shown to be strongly suppressed by Hf incorporation. Nevertheless, O transport was not reduced to the same extent. Oxygen isotopic tracing in conjunction with nuclear reaction analysis techniques evidences that oxygenic species from the gas phase diffuse through the dielectric layer, promoting both exchange with oxygen already present in the oxide and formation of new oxide. In view of that, the combination of different passivation strategies seems to be necessary in order to mitigate undesirable properties of GeO₂. Thus, GeO₂/Ge stacks were prepared incorporating Hf close to the oxide surface and N close to the GeO₂/Ge interface, aiming at combining the beneficial effects of each strategy. The resulting structure was more robust concerning the instabilities experienced with GeO₂/Ge stacks, indicating that the combination of passivation strategies constitutes a promising approach.