Chemical Liquid Phase Of Pbs Electrcal Prepared Membrane And Its Performance Study

Lead sulfide (PbS) components with high.responsivity and simple preparation technology can work stably at room temperature, which is widely used as infrared detectors in the NIR region (1～3μm). In order to prepare a multi-element transducer array of good performance, the polycrystalline thin film needs to be highly uniform and response at large area. In this paper, the effect of three process points as deposition, sensitization and retrogradation on PbS photoserisitivity thin film has been discussed.PbS films were deposited with different temperatures and agitation rates on glass substrates by chemical bath deposition (CBD). According to the comparison of their micro-structures and electrical properties, PbS thin film under optimized process has better preferred orientation corresponding to the (200) crystal plane and higher uniformity. Besides, the stability and operating temperature range of device has been promoted.In order to sensitize the PbS film, CVD high-temperature tube furnace has been used for annealing. When sensitizated with proper amount of oxidation (N/O=1:1), the n-p-n barrier of film tends to completely grow, therefore, carrier activation energy reaches to0.314eV, which result in great improvement of dark resistance and photoconductive sensitivity. Compared to pure oxygen annealing, nitrogen-oxygen annealing has improved the uniformity of composition and morphology of PbS thin film.The retrogradation of PbS infrared detector was carried out in the oven at125degree centigrade. When the agine time became longer, the square resistance and photoconductive sensitivity of detector has increased. According to the effect of different aging times on resistance-temperature properties, retrogradation at air atmosphere can be regarded as secondary annealing, which made a larger carrier activation energy of the film. After40hours of retrogradation, this improvement was most obvious.