Structure and composition effects on electrical and optical properties of sputtered PbSe thin films

Lead selenide (PbSe) thin films were grown on Si (111) substrates using magnetron sputtering, and the structure and composition effects on the photoelectric and optical properties of the sputtered PbSe thin films were studied using field emission scanning electron microscope, energy dispersive X-ray detector, X-ray diffraction, X-ray photoelectron spectroscopy, physical property measurement system and Fourier transform infrared spectroscopy. The optical band gaps of all the sputtered PbSe thin films ranged from 0.264 eV to 0.278 eV. The PbSe thin film prepared with oxygen flux 1.0 sccm, deposition time 240 min, sputtering power 150 W and substrate temperature 150 degrees C showed the highest resistance change rate under illumination, about 84.47%. The variation trends of the photoelectric and optical properties with the average crystal size, lattice constant, oxygen content and lattice oxygen percentage were similar, respectively. The sputtered PbSe thin films showed poor photoelectric sensitivity, when the average crystal size was similar to the Bohr radius (46 nm), while the photoelectric sensitivity increased almost linearly with the oxygen content in the thin films, indicating that both deviating the average crystal size from the Bohr radius and increasing the oxygen content are two direct and effective ways to obtain high photoelectric sensitivity in PbSe thin films. (C) 2015 Elsevier B.V. All rights reserved.