Isotopic effect between hydrogen and deuterium emission in silicon

We find an isotope effect between the breaking of SiH and SiD bands, using tight-binding molecular dynamics simulations. The vibrationally excited Si- D bending modes decay much more rapidly than Si-H bending modes, due to the coupling of SID modes with the interior silicon-phonon modes. The SiD bond is much more stable than the SiH bond. This stability explains the reduced degradation in deuterated metal-oxide-semiconductor (MOS) devices. For ger manium, the GeD and GeH bonds have little difference in their stabilities s ince their vibrational frequencies are greater than the interior Ge-spectru m, consistent with this vibrational coupling model. (C) 2000 Elsevier Scien ce B.V. All rights reserved.