Dislocation-Related Etch-Pits And Deep Level In Strain Relaxed Sige Layers

Strain relaxed SiGe epitaxial layers were grown on the compositionally graded layers on Si(001) substrates at 730 degrees C, and 900 degrees C by molecular beam epitaxy. We observed etch-pits by scanning electron microscopy and atomic force microscopy after Schimmel-etch with various time. The analyses show that the etch-pits are related to threading dislocations. The Schimmel-etch seems to follow the kinematic wave theory of dissolution and etch-pit formation. Deep level transient spectroscopy exhibits a hole trap in the present sample. The energy and the capture cross section of the hole trap are E(H)=E(V)+0.62 +/- 0.05 eV and sigma(H) similar to 5.5 H x10(-10) cm(2), respectively. This hole trap is associated with threading dislocations and/or misfit dislocations in compositionally graded layer.