Abstract
Structural, electrical, and ultrafast optical properties of furnace-annealed arsenic-ion-implanted GaAs (GaAs:AS + ) has been investigated for its applications in ultrafast optoelectronics. From these studies, we determine that GaAs substrates implanted with 200-keV arsenic ions at 10 16 ions/cm 2 and furnace-annealed at 500 °C-600 ° C would have recovered its crystallinity, be highly resistive, and exhibit picosecond photo-excited carrier lifetimes. The duration of the electrical pulses generated by photoconductive switches (PCS's) fabricated on the optimized material was ≈4 ps, The risetime (10%-90%) and 1/e falltime were, respectively, ≈2 and 3 ps These results were measurement-system limited. We estimated the actual response to be ≈2 ps, consistent with a photo-excited carrier lifetime of ≈ ps. The peak responsivity was ≥4×10 -3 A/W. The dark current for the GaAs : As + PCS biased at 40 V was as low as 5 nA, The break down field was higher than 150 kV/cm. These characteristics are comparable to those of state-of-the-art photoconductors such as LT-GaAs.