Deep Level Transient Spectroscopy Characterization of Defects Introduced in n-GaAs after Alpha Irradiation at 15 K

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Abstract
Using conventional deep level transient spectroscopy (DLTS), we have characterised 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, Eα7 and Eα9, were detected 0.07 eV and 0.19 eV below the conduction band, respectively. The introduction rates of Eα7 and Eα9 are calculated to be 41 cm-1 and 187 cm-1 respectively. It was observed that both defects obeyed first order annealing kinetics, with Eα9 being removed at 225 K and Eα7 at 245 K corresponding to the well known stage I annealing region. The annealing rate of Eα7 corresponds to an activation energy of 0.86 eV, with a pre-exponential factor of 1.0×1015 s-1; and the removal of Eα9 has an activation energy of 0.88 eV and a pre-exponential factor of 1.7×1017 s-1.