Fabrication and characterization of high photosensitivity CuS/porous silicon heterojunction photodetector

This study focused on the fabrication and characterization of CuS/porous Si heterojunction photodetector prepared by deposition of chemically sprayed CuS film on the porous silicon substrate prepared by anodization method. The optical and structural of CuS film and porous silicon PSi layer were investigated using x-ray diffraction, scanning electron microscope SEM, energy dispersive x-ray EDX, atomic force microscopy AFM, and UV-V-vis optical absorption. XRD studies confirm the CuS film deposited on glass substrate was polycrystalline in nature with hexagonal structure, while the XRD data of the CuS film deposited on PSi shows only single peak at 2 theta = 27 degrees corresponds to (101) plane. The optical properties results reveal that the direct optical bandgap of CuS was around 2.25 eV. SEM shows that the average wall size and pore size of the porous silicon were 200 nm and 550 nm, respectively, and the CuS film consists of spherical grains with average grain size of 45 nm. AFM data illustrates that the mot mean square of surface roughness of CuS film 9.1 nm. PL spectrum of PSi shows a strong emission peak at 576 nm. The optoelectronics properties of CuS/PSi/c-Si photodetector including dark and illuminated I-V characteristics, spectral responsivity, quantum efficiency, and detectivity were measured at mom temperature. The responsivity of the photodetectors at peak of response 500 nm was 2.15 A/W.