Deep levels in ion-implanted and rapidly thermally annealed p+n junctions were investigated. The samples were co-implanted with Mg and Si. Additional P implantation was also sometimes carried out. Deep-level transient spectroscopy and capacitance-voltage transient techniques were used to characterize the traps. In control samples which were implanted only with Mg, 4 deep electron levels that were located in the upper half of the band-gap (0.45, 0.20, 0.25 and 0.27eV below the conduction band) were detected by means of deep-level transient spectroscopy. In the case of Mg-Si-implanted and Mg-P-Si-implanted samples, only 2 levels were observed (0.25 and 0.27eV below the conduction band). With regard to the disappearance of the E2 (0.45eV) level, it was noted that Si-implanted atoms could be located at P vacancies, thus giving rise to a new trap. Therefore, the number of P vacancies which were associated with the E2 level would decrease and the centre would not be detected. In the case of the E4 (0.20eV) level, it was noted that Si atoms could be also sited on In sites. Thus, the concentrations of In vacancies which were involved with the E4 trap decreased; thus diminishing the centre concentration. The E6 (0.25eV) deep level was attributed to a defect which involved implanted Mg ions. Its sudden decrease, which occurred when Si or P plus Si implantation was carried out, supported this attribution since the damaged areas which resulted from such implantation could prevent the inward diffusion of Mg atoms. In the case of the E7 (0.27eV) trap, non-uniform and V-shaped profiles were observed. The associated complex emission rate spatial distribution suggested that this level involved a group of emission centres which contributed to an emission energy band. There was a possible relationship between this level, and dislocations that resulted from the implantation.

L.Quintanilla, S.Dueñas, E.Castán, R.Pinacho, R.Peláez, J.Barbolla, J.M.Martín, G.González-Diaz: Semiconductor Science and Technology, 1998, 13[4], 389-93