X‐ray characterization of epi‐Ge/Pr2O3/Si(111) layer stacks by pole figures and reciprocal space mapping

Abstract

AbstractAn epi‐Ge/Pr2O3/Si(111) layer structure prepared by consecutive steps of epitaxial deposition and annealing is used to demonstrate the possibility of a complex characterization by combination of different X‐ray diffraction techniques. Especially pole figure measurements, reciprocal space mapping (RSM) and high resolution (HR) Θ/2Θ scans at selected inclined netplanes were successfully used to determine the in‐plane lattice orientation of the layers relative to the substrate, the strain state of all layers and the structural perfection of the epi‐Ge film. It was found that the major part of the epi‐Ge layer has the same type A stacking orientation as the Si substrate, but about 0.6% is of type B. The Pr2O3 buffer layer exhibits type B only. The strain state of oxide and epi‐Ge was determined, and a small difference in the lattice constant of type A and B epi‐Ge was found. Microtwins lying in inclined {111} planes were unambiguously identified by pole figure measurements as the dominating structural defects in the epi‐Ge layer. They cause a characteristic scattering pattern in reciprocal space maps. The proposed combination of X‐ray techniques allows a relatively fast, integral and non‐destructive analysis of heteroepitaxial semiconductor oxide semiconductor structures.