Photocurrent spectra from PbS photovoltaic infrared detectors using silver nanowires as plasmonic nano antenna electrodes.

We discussed structural and electrical properties of PbS films deposited by chemical bath deposition. The crystallite size of our films measured by transmission electron microscope was as large as 0.2 μm in a lateral direction and 1 μm in a vertical direction, and we obtained a high mobility value of 60 cm2 V-1 s-1 at room temperature. We also demonstrated PbS photovoltaic infrared detectors using silver nanowires as transparent electrodes, whose spectral response was measured by Fourier transform infrared spectrometer. The cut-off wavelength was ∼3 μm at room temperature and ∼4 μm at 10 K. At 100 K, a pronounced photocurrent peak was observed at λ = 3.7 μm. Using finite difference time domain simulations, we demonstrated that silver nanowires worked as nano antennas for generating surface plasmons, resulting in the enhancement of photocurrent. The pronounced photocurrent peak wavelength corresponds to the wavelength where the silver nanowires were located near the constructive interference.