Electron spin resonance observations were made of an anisotropic paramagnetic defect at the interface of epitaxially grown Ge3N4/(111)Ge entities with nm-thin Ge3N4 layers. The defect exhibited trigonal C3v symmetry characterized by g∥ ≈ 2.0023 and g⊥ ≈ 2.0032, and was observed most prominently after 10eV optical excitation, with maximum areal density ≈ 2 x 1011/cm2. The defect was suggested to involve the Ge K-type center, its occurrence appearing to be inherent to specific hetero-epitaxial interface matching.

Trigonal Paramagnetic Interface Defect in Epitaxial Ge3N4/(111)Ge. A.P.D.Nguyen, A.Stesmans, V.V.Afanasev, R.R.Lieten, G.Borgs: Applied Physics Letters, 2009, 95[18], 183501