Dual ion implantations of Si + As and S + As into GaAs

As+ implantation has been used to compensate the As loss during annealing for Si- or S-implanted GaAs. The As+ implantation was at an energy range of 25-100 KeV to a dose range of 1012-1015cm-2. The Si+ or S+ implantation was at 150 or 50 KeV respectively to the same dose, 2 x 1013cm-2. By using the measurements of the Hall effect and sheet resistivity, the activation efficiency and mobility of the dually implanted sample with Si+ and As+ (25 KeV, 1 x 1013cm-2) after TA at 1050 degree C for 6s increase by 21 and 18% respectively over those of the singly Si-implanted sample with Si+ and As+ (100 KeV, 1 x 1013cm-2) increase by 63 ant 30% respectively over those of the singly Si-implanted sample after FA at 800 degree C for 30 min. Also, the density of SiAs and VGa determined by 20K PL spectra decreases of dually Si- and As-implanted samples. The activation efficiency and mobility of the dually implanted sample with S+ and As+ (40 KeV, 1 x 1013cm-2) after TA at 1100 degree C for 12s increase by 18 and 16% respectively over those the singly S- implanted sample. The annealing behavior after As+ implantation is discussed. 9 refs., 7 figs