Role of the Oxygen Content in the GeO2 Passivation of Ge Substrates as a Function of the Oxidizer

The electrical quality of the GeO2/Ge interface, prior to and after Gd2O3 deposition, has been investigated as a function of the oxidizer (atomic O, O2, O3) used for the GeO2 based passivation of the Ge surface. In particular, the density of interface traps depends on the details of the Ge oxidation process and on the reactivity of the GeO2 passivation layer with the overlying Gd2O3 film. Complementary compositional depth profiling analysis shows that the oxygen content in the interfacial layer varies as a function of the type of oxidizer and plays a key role in dictating the interface chemistry and the electrical features of the MOS structures.