DIRECT EVIDENCE FOR LOCALIZED MOTION OF HYDROGEN IN CD-H COMPLEXES IN SILICON

The locally restricted motion of hydrogen and deuterium trapped at Cd acceptors in silicon has been studied by Perturbed-angular-correlation spectroscopy. Close Cd-H and Cd-D pairs were identified by their characteristic electric-field gradients. The kinetics of these complexes was extracted directly from the time spectra. Between 270 and 430 K clear evidence has been found for thermally activated motion of hydrogen or deuterium about the Cd with an activation energy of 0.21 eV for both hydrogen as well as deuterium. The isotopic-mass-dependent attempt frequencies are on the order of 10(9) s-1. The ratio of the frequency for hydrogen relative to that for deuterium is nu-H/nu-D = 3.3(1.3).