Analytical, structural and electrical characterization of SiGe layers by electron microbeam techniques

Abstract

k-ratios of Ge-L_α and Si-K_α measured at different beam energies allow to evaluate simultaneously composition and thickness of SiGe layers on a Si substrate. A simple technique applying backscattered electrons also enables estimation of composition of bulk SiGe and of composition and thickness of relatively thick (∼200 nm) SiGe layers on Si. Electron channeling patterns of pseudomorphic SiGe/Si structures and of pure Si substrate show no significant differences whereas in relaxed structures a smearing of the pattern with increasing density of misfit dislocations is observed. Under particular conditions the technique of the electron beam induced current permits imaging of recombination-active misfit dislocations with a spatial resolution around 0.2 μm. Moreover, a repulsion of holes due to the valence-band offset in a n-Si/SiGe heterostructure was detected.