Electronic properties of Ge dangling bond centers at Si1−xGex/SiO2 interfaces

Comparison between densities of paramagnetic Ge dangling bond defects and shallow acceptor traps at interfaces of the condensation-grown Si1−xGex layers (0.28≤x≤0.93) with thermal SiO2 as a function of Ge fraction, x, reveals quantitative agreement. Moreover, defect densities detected in both magnetic resonance and electrical experiments exhibit reversible passivation-depassivation behavior with respect to hydrogen indicating observation of the same defect (Ge Pb1 center). The corresponding energy level is estimated to lie at 0.35±0.10 eV above the valence band in bulk Si, which makes these defects behave as shallow acceptors in Ge-rich Si1−xGex.