Structural, morphological, electrical and optical properties of PbSe thin films sputtered at various pressures

Optical band gap control of lead selenide (PbSe) thin films is essential for realizing the practical applications. In this paper, PbSe thin films have been deposited by radio frequency (RF) magnetron-sputtering with varied sputtering gas pressures from 0.5 to 4.0 Pa. A systematical investigation of the film properties was carried on. X-ray diffractometry, atomic force microscopy, Hall effects measurements and UV-vis spectroscopy analyses were performed to investigate the crystal structural, morphological, electrical and optical properties of the films. The sputtering pressure has a significant effect on the structure and properties of the PbSe thin films. The intensity of the preferred orientation (200) increases with sputtering pressure up to 3.0 Pa, and then decreases at 4.0 Pa. The films are composed of equiaxed spherical crystals, whose roughness tends to increase with pressure. According to the Hall effect measurements, the resistivity linearly decreases from 1.6 Ω cm to 0.02 Ω cm, and the carrier concentration decreases from 1.19 × 1020 cm−3 (0.5 Pa) to 4.0 × 1017 cm−3 (4.0 Pa). The optical band gap ranges from 1.22 to 1.52 eV. The suitable pressure range is 2.0-3.0 Pa in this study.