Electrical, Structural, and Chemical Analysis of Defects in Epitaxial SiGe -Based Heterostructures

Abstract

The electrical and structural properties of defects in epitaxial with content from 5 to 41% are investigated using electron-beam-induced current contrast measurements and bevel polishing with preferential defect etching. At room temperature, no electrical activity of misfit and threading dislocations is evident for wafers with 14, 21, and 41% , while at a crossgrid array of misfit dislocations is observed on all these wafers and shallow level traps from threading dislocation defects are seen on the 41% wafer. Thermal treatments reduce the electrical activity of the defects. Bevel polishing and preferential chemical etching with the Wright and Secco etches are utilized to analyze the dislocation density and distribution throughout the heterostructure. The etch chemistry difference between and is characterized as a function of content to correctly interpret results. The etch rate increases with increasing concentration up to 15% , then saturates at a rate of for higher values, which is about 3 times that for an unstrained substrate. The etch rate is strongly dependent on the defect concentration, stress, and defect density in the layers.