Optically detected magnetic resonance (ODMR) in a Si1−xGex: H-alloys

Abstract A systematic study of ODMR has been performed on alloys of a-Si 1-x Ge x :H covering the whole range of x. A queching- and an enhancing line (Q and E) are identified, their spectral dependence is studied and the line parameters are determined. The Q-line shows that up to x ≈ 0.25 the Si-dangling bonds are the dominant centers for non-radiative recombination and that the relevant process is tunneling of band tail electrons to dangling bonds. The enhancing line is attributed to exchange coupled electron-hole pairs involving deep tail states which may derive from Ge-Ge bonding states.