High-resolution core-level photoemission study of $CF4$-treated $Gd2O3(Ga2O3)$ gate dielectric on Ge probed by synchrotron radiation

High-resolution core-level photoemission analysis using synchrotron radiation was used to investigate the superior electrical performance of $aGa2O3(Gd2O3)$ gate dielectric on Ge(001) after $CF4$ treatment. Prior to the treatment, a thin germanate-like oxide layer that formed at the interface prevented Ge from diffusing to the surface. The Ge surface retained a small amount of buckled dimers from the as-grown sample. The buckled dimers were quickly removed by $CF4$ plasma treatment followed by an annealing process, resulting in a more uniform interface than that of the as-grown sample. The detailed interfacial electronic structure for the untreated and treated samples are presented.