Effects of the high-temperature sensitization in argon atmosphere on the microstructure and properties of polycrystalline PbSe films

PbSe film used for infrared detection is generally subjected to sensitization at ≤723 K in air, oxygen, and/or iodine vapor for enhancing its optoelectronic performance. In this work, the PbSe film deposited by chemical bath deposition (CBD) method was firstly sensitized at high temperatures (773–848 K) in argon atmosphere. The phase composition, surface and cross-sectional morphologies, carrier concentration and mobility, and detectivity of the PbSe films before and after sensitization were investigated systematically. The optimal PbSe film sensitized at 823 K processes the average grain size of ∼520 nm, carrier concentration of 9.9 × 1016 cm−3, carrier mobility of 13.9 cm2/N·s, and detectivity of 2.31 × 109 Jones for 1550 nm laser radiation. In particular, the optimized PbSe film displays high reproducibility, fast response and excellent high frequency stability. A potential barrier model is proposed to explain the highest optoelectronic performance, where the evaporation of the Se at grain boundaries can generate n-type semiconductor area and the diffusion of oxygen into PbSe grain lattice contributes to inhibit the recombination of carriers. This work provides a new strategy for sensitization of lead chalcogenides thin films.