Picosecond responses of low-dosage arsenic-ion-implanted GaAs photoconductors

Abstract

Ultrafast optoelectronic characteristics of GaAs implanted with 200 keV arsenic ions at dosage as low as 10(13) ions/cm(2) are reported. Ultrashort photoexcited carrier lifetimes of 0.23+/-0.02, 0.87+/-0.02, and 3+/-0.2 ps were determined for as-implanted, rapid thermal annealing (RTA) (600 degrees C for 30 s) and furnace-annealed (600 degrees C for 30 min) arsenic-ion-implanted GaAs or GaAs:As+, respectively. The switching response of photoconductive switches (PCSs) fabricated on the latter two materials were similar to 3 and 8 ps, respectively. The leakage current of the PCS fabricated on furnace-annealed sample was as low as 30 nA. The breakdown fields exceeded 150 (instrument-limited) and 90 kV/cm for furnace-and RTA-annealed samples, respectively. The optical responsivity of low-dosage arsenic-implanted GaAs photoconductive switch can be as high as 0.01 A/W. This also compared favorably with the same device made on state-of-the-art photoconductor such as molecular-beam epitaxy grown GaAs at low temperatures. (C) 1997 American Institute of Physics.