In-Plane Biaxial Strain Evaluation Induced in Ge1-X Sn x Films Using Oil-Immersion Raman Spectroscopy

Abstract

We performed evaluation of anisotropic strain relaxation in the patterned Ge1-x Sn x mesa by Raman spectroscopy. For strain evaluation, several coefficients, e.g., strain shift coefficient b and phonon deformation potentials (PDPs: p and q), are indispensable. In this study, using thin Ge1-x Sn x films which were epitaxially grown on Ge substrate by MOCVD, the b coefficient and PDPs were derived. From results of Raman spectroscopy and XRD, the b coefficient was -399.3±5.6 cm-1. And, the p and q show only small variation in the Sn concentration range less than 3.2%. These derived coefficients were used to evaluate the biaxial strain in the patterned Ge1-x Sn x mesa by oil-immersion Raman spectroscopy. As a result, we confirmed uniaxial strain relaxation in the Ge1-x Sn x stripe pattern.