Local motion of hydrogen around platinum in Si

We have studied the local motion of hydrogen around platinum in Si from the recovery kinetics of stress-induced reorientation of the Pt-H2 complex. We evaluated the degree of alignment using isothermal DLTS (IT-DLTS) technique under a stress of 0.6 GPa along the 〈1 1 1〉 direction at 70 K where hydrogen could not move. We observed the recovery at temperatures of 80-85 K only in the singly negative charge state of the Pt-H2 complex, indicating the similar charge-state-dependent motion of hydrogen as in the stress-induced reorientation of the complex. We obtained an activation energy of 0.25 eV for the recovery process, being comparable with that for the stress-induced reorientation.