Deuteron Magnetic Resonance Spectral Componentes in a-Si:H,D

Abstract

Deuteron magnetic resonance (DMR) in a-Si:D,H and a-Si:D films resolves 5 distinct spectral components. For the bonded deuterium, there are the rigid deuteride Si-D configurations and the rotating silyl SiDXH3-X groups. These components appear as a 66 kHz and a 22 kHz quadrupolar Pake doublet respectively. DMR shows a central spectral component associated with D2 and HD molecules inside microvoids. Its linewidth is due to the distribution of surface-generated static electric field gradients (EFG) from microvoids. A 76 kHz quadrupolar broadened Pake doublet is present at low temperatures and is associated with p-D2 molecules whose rotational transition rates Γm are no more than ωd (nuclear spin-molecular coupling frequency) for molecules in the presence of large EFG’s. Deuteron multiple spin echoes uniquely identify o-D2 molecules whose rotational ground states are admixed by the EFG. A para to ortho (p-o) conversion experiment of D2 done on a perdeuterated a-Si sample at 4.2 K provides further resolution of the bonded D and molecular D2 configurations. For the D2 molecule dynamics we measure a phase transition temperature and p-o conversion constant that suggest the presence of standard vapor pressure D2 inside the microvoids.