DEEP-LEVEL TRANSIENT SPECTROSCOPY CHARACTERIZATION OF DEFECTS INTRODUCED IN N-GAAS AFTER ALPHA-IRRADIATION AT 15-K

Using conventional deep level transient spectroscopy (DLTS), we have c haracterised the defects introduced in OMVPE n-GaAs at 15 K by 5.4 MeV alpha particle irradiation from an americium 241 radio-nuclide. After this low temperature irradiation two new defects not yet reported for alpha irradiated GaAs before, Ealpha7 and Ealpha9, were detected 0.07 eV and 0.19 eV below the conduction band, respectively. The introduct ion rates of Ealpha7 and Ealpha9 are calculated to be 41 cm-1 and 187 cm-1 respectively. It was observed that both defects obeyed first orde r annealing kinetics, with Ealpha9 being removed at 225 K and Ealpha7 at 245 K corresponding to the well known stage I annealing region. The annealing rate of Ealpha7 corresponds to an activation energy of 0.86 eV, with a pre-exponential factor of 1.0 x 10(15) s-1; and the remova l of Ealpha9 has an activation energy of 0.88 eV and a pre-exponential factor of 1.7 X 10(17) s-1.