Top-Gated HfO₂-Capped InP Nanowire Photodetector With Low Noise and High Detectivity

Due to the surface oxide layer or surface defects in the preparation process of nanowires (NWs), resulting in large dark current noise and low detectivity, which seriously limits the detection performance of photodetectors. Here, we successfully synthesized high-quality single-crystalline InP NWs utilizing chemical vapor deposition method and fabricated high-performance top-gated single InP NW photodetectors. The ultra-low noise dark current and high detectivity are obtained, mainly because the passivation layer of HfO2 reduces the defect density on the NW surface and suppresses the background dark current. The low frequency noise current power of the top-gated device is about
$2.0\times 10^{ - 28}\,\,\text{A}^{2}$
. Under near-infrared 830 nm laser illumination with 0.05 mW cm
$^{ - 2}$
, the top-gated single InP NW photodetector exhibits high responsivity of
$1.0\times 10^{5}$
A
$\text{W}^{ - 1}$
, external quantum efficiency of
$1.4\times 10^{7}$
%, and detectivity of
$1.1\times 10^{16}$
Jones, the rise time and fall time are about 7.2 ms and 13.6 ms, respectively. The results demonstrate that the top-gated HfO2-capped InP NWs FET have a broad application in high-performance and low-power photodetectors.