Laser-induced thermal effect on the electrical characteristics of photosensitive PbSe films

The paper presents a study of the effect of laser irradiation of crystalline chalcogenide films of lead selenide (PbSe) on their electrical characteristics caused by irreversible modification of the structure due to valence reconfiguration of lead as a result of its oxidation. The study of the modification features of the electrical properties of the films was carried out because of laser exposure to nanosecond pulses with a wavelength of 1064 nm. Measurements of the electrical characteristics of PbSe films were carried out using the four-probe method. It was shown that when the current was directed parallel to the laser tracks recorded in the darkening mode, the resistance of the modified film decreased by 44 % compared to the original sample, and with the perpendicular direction of the current, the resistance increased by 153 %. The resistance of the film increased more than 27 times after laser irradiation in the bleaching mode, regardless of the direction of the current relative to the laser tracks. The experimentally measured temperature and its gradient along the laser spot on the film in the darkening and bleaching modes turned out to be in good agreement with the proposed mathematical model of the thermal effect of laser pulses. It has been shown that the processes of laser modification of films occur at lower temperatures than during standard heat treatment in a furnace. The obtained results can be applied in the development of photodetectors in the middle IR range of the spectrum based on PbSe film.