Material and ultrafast optoelectronic properties of furnace-annealed arsenic-ion-implanted GaAs

Structural, electrical, and ultrafast optical properties of furnace-annealed arsenic-ion-implanted GaAs (GaAs:As/sup +/) 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/sup 10/ ions/cm/sup 2/ and furnace-annealed at 500/spl deg/C-600/spl deg/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 (PCSs) fabricated on the optimized material was /spl ap/4 ps. The risetime (10%-90%) and l/e falltime were, respectively, /spl ap/2 and 3 ps. These results were measurement-system limited. We estimated the actual response to be /spl ap/2 ps, consistent with a photo-excited carrier lifetime of /spl ap/1.8 ps. The peak responsivity was /spl ges/4/spl times/10/sup -3/ A/W. The dark current for the GaAs:As/sup +/ PCS biased at 40 V was as low as 5 nA. The breakdown field was higher than 150 kV/cm. These characteristics are comparable to those of state-of-the-art photoconductors such as LT-GaAs.