Probing the SiGe virtual substrate by high-resolution channeling contrast microscopy

Abstract

Relaxed, epitaxial SiGe layers with low densities of threading dislocations are grown by linearly grading the Ge composition. However, such compositionally graded SiGe layers (virtual substrates) often result in a cross hatch surface morphology which affects subsequent device processing. Here, we report on high-resolution channeling-contrast-microscopy (CCM) measurements on such virtual substrates grown by gas-source molecular-beam epitaxy and low-pressure chemical vapor deposition. A two-MeV He+ beam focused to a submicron spot is used in these CCM measurements to obtain both lateral and depth-resolved information on the cross hatch features observed and their association with a slight lattice tilt. © 2002 American Institute of Physics.