The detention performance enhancement of single gallium arsenide nanowire photodetector by nitrogen plasma treatment

Sensors based on gallium arsenide (GaAs) nanowires (NWs) have excellent sensitivity and can directly detect individual virus particles and individual DNA molecules. GaAs NW photodetectors have attracted wildly attentions due to their direct band gap, specific surface area and high optical absorption coefficient. However, GaAs NWs suffer the problem of serious surface states, leading to the development of high performance GaAs NW photodetectors. Plasma treatment with inert gas is one of the important methods to reduce the density of surface states. In this paper, the effect of nitrogen plasma treatment on the performance of GaAs NW photodetector is investigated. The results show that the light current of GaAs NW photodetector is obviously increased. Besides, the responsivity, specific detectivity and external quantum efficiency (EQE) are also improved. Under 808 nm laser with the light intensity is 2966.8 mW cm−2, the responsivity changes from 56.4 A W−1 to 117.6 A W−1 and 18.7 A W−1, the specific detectivity changes from 4.7 × 1011 Jones to 9.9 × 1011 Jones and 3.2 × 1011 Jones, the EQE changes from 13 146% to 27 434% and 4359% when the nitrogen plasma treatment time is 0 s, 10 s and 20 s, respectively. This may be related to the defect states density of NWs is changed after nitrogen plasma treatment. This work promotes the further development of GaAs NW photodetectors for biosensing techniques.