Multifrequency electron-spin-resonance study revealed a non-trigonal Ge dangling-bond type interface defect in SiO2/(100)GexSi1−x/SiO2/Si heterostructures grown by the condensation method. The center, exhibiting monoclinic-I (C2v) symmetry, with principal g values g1 = 2.0338, g2 = 2.0386 and g3 = 2.005 4 and lowest g value dangling-bond direction 24° off a <111> direction towards the [100] interface normal, was observed in maximum densities for x ~ 0.7, the signal disappearing for x≤0.45 and x≥0.93. Neither Si Pb type nor trigonal Ge dangling bond defects was observed, permitting unobscured spectral analysis. Based on its electron-spin-resonance parameters, including g matrix and symmetry, it was suggested to concern a Ge Pb1-type center, that is, not a trigonal basic Ge Pb(0)-type center (Ge3≡Ge•), thus exposing a unique interface mismatch healing as function of substrate Ge fraction. Its properties were discussed within the context of the thus far elusive role of interfacial Ge dangling-bond defects in Ge insulator structures, encompassing theoretical inferences

Nontrigonal Ge Dangling Bond Interface Defect in Condensation-Grown (100)Si1−xGex/SiO2. A.Stesmans, P.Somers, V.V.Afanasev: Physical Review B, 2009, 79[19], 195301