The passivation of Be acceptors in GaAs by exposure to a hydrogen plasma

Infrared absorption measurements have been made of the localised vibrational modes (LVM) of 9 Be Ga acceptors in GaAs grown by MBE for as-grown, electron-irradiated and hydrogen-passivated samples. The dipole moment has been determined for the Be 0 line at 482.1 cm -1 . The strength of this line decreased during electron irradiation and it is inferred that Be impurities form complexes with intrinsic defects. In passivated samples H-Be complexes form and stretching modes from H and D are found at 2037 and 1471 cm -1 respectively. Surprisingly the width of the former line is some three times greater than that of the latter. Only one mode of the complexes Be has been found at 555.7 cm -1 . The hydrogen is believed to occupy a bond centre position between the Be atom and a nearest neighbour As atom. A comparison is made with H-Zn complexes.