Surface Chemistry and Nanoscale Wet Etching of Group IV Semiconductors in Acidic H2O2 Solutions

In this atomic-scale study on technologically relevant group IV semiconductors, Ge and SiGe, we relate surface chemistry, in particular the nature of surface oxides, to wet etching kinetics. ICP-MS quantification of Ge in HCl solution containing H2O­2 as the oxidizing agent showed that the Si bulk concentration strongly impacted the etching kinetics. Post operando synchrotron XPS provided insight into the surface oxide chemistry involved in the etching process: a non-homogeneous porous layer with a depletion of Ge components at the outer surface due to pull out effects.