Microstructure and optic-electric performance of SiGe/Si heterostructures

In order to reduce dark current density for the silicon-based Ge infrared detector, the best way is to develop high quality buffer layers with low dislocation density as well as high relaxation degree. In this paper, Si
_1-x
Ge
_x
/Si heterostrutures have been grown to study the Ge composition, roughness influenced dislocation density and strain relaxation. High resolution XRD results and swing curve (224) analysis indicate that the strain relaxation of thin film after annealing is larger than 90%. The film dislocation density is lower than 8.0×10
⁵
/cm
²
, while the average roughness changes between 1.4 nm and 2.0 nm. Such buffer layer can be applied to grow high quality Ge alloy infrared detector.