(Invited) Identification of Intrinsic Point Defects at GexSi1-x/Oxide Interfaces by ESR Probing

Abstract

We report on the obvervation by electron spin resonance (ESR) of two paramagnetic Ge dangling bond (DB)-type defects at Ge/oxide interfaces. One, detected in SiO2/(100)GexSi1-x/SiO2/Si hetero-structures grown by the condensation method, exhibits monoc-linic-I (C2v) symmetry, with principal g values g1=2.0338(3), g2=2.0386(6), g3=2.0054 and g3 axis (DB) direction 24{plus minus} 2{degree sign} off a <111> direction towards the [100] interface normal. The defect reaches maximum densities for x~0.7, to disappear for x{less than or equal to}0.45 and x{greater than or equal to}0.87. It is suggested to concern a Ge Pb1-type center, i.e., not a trigonal basic Ge Pb(0)-type center (Ge3≡Ge•), thus exposing a unique interface mismatch adaptation as function of substrate Ge fraction. The second one, observed at the interface of epitaxially grown Ge3N4/(111)Ge entities with nm-thin Ge3N4 layers, shows trigonal (C3v) symmetry characterized by g//~2.0023 and g⊥~2.0032. Based on comparision of its salient ESR features with previous theoretical results, the defect is suggested to concern the Ge K center.