  Defects are detrimental for optoelectronics devices, such as stacking faults
can form carrier-transportation barriers, and foreign impurities (Au) with
deep-energy levels can form carrier traps and non-radiative recombination
centers. Here, we first developed self-catalyzed p-type GaAs nanowires (NWs)
with pure zinc blende (ZB) structure, and then fabricated photodetector made by
these NWs. Due to absence of stacking faults and suppression of large amount of
defects with deep energy levels, the photodetector exhibits room-temperature
high photo responsivity of 1.45 x 105 A W^-1 and excellent specific detectivity
(D*) up to 1.48 x 10^14 Jones for low-intensity light signal of wavelength
632.8 nm, which outperforms previously reported NW-based photodetectors. These
results demonstrate that these self-catalyzed pure-ZB GaAs NWs to be promising
candidates for optoelectronics applications.
