Structure and dynamics of the Be-H complex in GaAs

The symmetry and reorientation kinetics of the Be-H complex in GaAs have been determined in a uniaxial-stress study. The splitting of the 2036 ${\mathrm{cm}}^{\mathrm{-}1}$ vibrational absorption band under stress shows that the complex has trigonal symmetry. The size of the splitting is large and is consistent with a bond-centered position for the H atom, similar to the case of B-H in Si. At temperatures near 120 K the complex can be aligned by an applied stress. A study of the annealing kinetics of the alignment shows that the motion of H from bond-centered site to bond-centered site about the Be acceptor is thermally activated with an energy of 0.37 eV.