STRAIN-MEASUREMENT IN THIN PSEUDOMORPHIC SIGE LAYERS OF SUBMICRON WIRES USING RAMAN-SPECTROSCOPY

The internal strain in thin heteroepitaxial Si1-xGex layers was invest igated before and after etching the material between the remaining nar row stripes. The strong inner stress in pseudomorphic heterostructures , caused by the difference in the lattice constants of Si and Si1-xGex , relaxes in small regions after removing the surrounding layer materi al which mediates the stress. Strain and relaxation were determined fr om micro-Raman measurements. These measurements were compared with cal culations using a two-dimensional finite element program to predict th e strain distributions in Si1-xGex layers. Assuming a pure elastic rel axation of the pseudomorphic strain we have found a reasonably good ag reement between the measured and calculated Raman shifts.