Impact of strain on the passivation efficiency of Ge dangling bond interface defects in condensation grown SiO_2/Ge_xSi_(1-x)/SiO_2/(100)Si structures with nm-thin Ge_xSi_(1-x) layers

摘要

Hydrogen passivation of germanium dangling bond defects observed as paramagnetic GeP_(b1) centers at the Ge_xSi_(1-x)/SiO_2 interfaces is studied as a function of Ge concentration and thickness of the Ge_xSi_(1-x) layer. By correlating the results obtained by three independent defect-sensitive methods - electron spin resonance spectroscopy, ac conductance of the Ge_xSi_(1-x) layer, and the positron annihilation spectroscopy - with the results of strain measurements by high-resolution X-ray diffractometry, we found that the density of the Ge dangling bonds reflects residual strain in the Ge_xSi_(1-x) layer. Furthermore, in the layers with high strain the hydrogen passivation efficiency of dangling bonds is found to decrease, suggesting a considerable spread in the activation energies of the passivation/depassivation reactions.