Photoluminescence in deuterated highly doped GaAs(Zn)

The passivation of Zn acceptors by atomic deuterium in heavily doped p-type GaAs is investigated by photoluminescence (PL) and infrared reflectance measurements. A large variation in the optical gap is observed, resulting from changes in the free-hole concentration. A broad PL band in the range 1.30 1.45 eV occurs after deuteration. This band is not related to plasma or radiation damage at the surface, but originates in the bulk of the deuterated layer. Using secondary-ion-mass spectrometry and thermal effusion combined with etch-back experiments, it is demonstrated that a large amount of deuterium (>1020 cm-3) coexists with the Zn-D complexes in the passivated region, in the form of electrically inactive species.