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Black phosphorus (BP) thin film has highlighted its potential in the photoelectric detection field due to its wide-spectrum and high-absorption capacity. However, the fabrication of controllable and highly quality BP film in large dimensions remains a huge challenge. Herein, we creatively fabricated a centimeter-size highly crystalline BP thin film on the bare silicon substrate using a space-confined chemical vapor transport technique, and we in situ constructed a self-driven BP-based metal–semiconductor–metal photodetector. The as-constructed photodetector achieves a high responsivity of up to 500 mA/W, an external quantum efficiency of 42.1%, a maximum specific detectivity of 3.82 × 1010 cm Hz1/2 W−1, and a small noise-equivalent-power of 3.97 × 10−15 W Hz−1/2 under zero bias voltage at 1550 nm illumination. This work provides a strategy to effectively prepare BP thin film for in situ manufacturing self-driven photodetector, which marks a significant step forward in the integration of BP into the industrial settings. [ABSTRACT FROM AUTHOR]

• A liquid sensitization of lead selenide thin films for mid-infrared detection. • Iodination of PbSe films in KI solution followed by high temperature sensitization. • The maximum detectivity of the sensitized films was 2.27 × 109 Jones. In pursuit of addressing the inherent challenges associated with gas partial pressure control and non-uniform diffusion of solid iodine encountered in conventional sensitization methods, this study delves into the impact of liquid sensitization on the structural and electrical properties of lead selenide (PbSe) films. The sensitization process entails iodination of PbSe films within varying concentrations of potassium iodide (KI) solutions, followed by high-temperature sensitization. The phase composition, surface morphologies, carrier concentration and mobility, and detectivity of the PbSe films after sensitization were investigated systematically. Our findings illuminate the transformative potential of liquid iodine sensitization in the modification of the crystal boundary barrier within PbSe films, thereby engendering substantial enhancements in both structural and electrical attributes. Iodine assumes a pivotal role in the orchestration of this boundary barrier modulation, which, in turn, has birthed an innovative methodology for crafting high-performance PbSe photodetectors. Remarkably, when films were sensitized with a KI concentration of 0.05 M, the maximum detectivity achieved reached an impressive 2.27 × 109 Jones. This study not only deepens our understanding of the underlying mechanisms responsible for the optoelectronic response of PbSe films but also underscores the immense potential of liquid iodine sensitization as a promising way for elevating their overall performance. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • The PbSe film was firstly sensitized at high temperature (over 773 K) in Ar. • High reproducibility, fast response and excellent high frequency stability. • The detectivity of 2.3 × 109 Jones is achieved. • A potential barrier model is proposed. [ABSTRACT FROM AUTHOR]

Lead sulfide (PbS) thin films were initially deposited through chemical bath deposition, followed by sensitization in a pure oxygen atmosphere at 600 °C. To investigate the influence of varying oxide layer states on the photoelectric properties of thermally sensitized PbS thin films, the surface oxide layer of the sensitized films was selectively removed using KOH etching. As the etching duration increased, a gradual decrease in surface oxygen content was observed, accompanied by an initial increase and subsequent decrease in detectivity. Notably, the optimum detectivity value (6.92 × 109 cm Hz1/2 W−1) was achieved after 10 s of KOH etching. Our investigation was further supplemented with field emission scanning electron microscopy and X-ray diffraction analyses to gain insights into the impact of the oxide layer state on the photoelectric properties of PbS thin films. Our findings led to the proposal of a dual conduction mechanism for carrier transport within PbS film. In the case of as-grown PbS films, carrier transport primarily occurs via crystal boundary transition. However, after oxygen sensitization, the formation of an oxygen-rich carrier channel at the crystal boundary shifts carrier transport dominance towards crystal boundary transport. The combined influence of both transmission mechanisms serves as a primary driver for the observed changes in the photoelectric properties of PbS films. • Lead sulfide thin films were sensitized in a pure oxygen atmosphere at 600 °C. • A dual conduction mechanism for carrier transport within the films, with as-grown films crystal boundary transition. • Oxygen-rich channel shifts carrier transport dominance towards crystal boundary transport for photoelectric properties. [ABSTRACT FROM AUTHOR]

• The PbSe films were effectively sensitized using a two-step sensitization technique. • The detectivity of 2.25 × 109 Jones is achieved. • A potential carrier transport structure is proposed. An effective two-step sensitization technique was implemented in PbSe thin films, leading to a remarkable improvement in the optoelectronic performance of PbSe photodetectors. The phase composition, surface and cross-sectional morphology, temperature-dependent carrier concentration and mobility as well as the detectability of PbSe films after sensitization were systematically investigated using characteristic techniques. The optimal PbSe film oxygen sensitized at 450 °C exhibited a room-temperature photodetection with a carrier concentration of 5.31 × 1016 cm−3, carrier mobility of 16.52 cm2/V−1s−1, and detectivity of 2.25 × 109 Jones. High-temperature argon heat treatment and oxygen sensitization of PbSe films are expected to suppress recombination losses and significantly improve the optoelectronic properties of sensitized PbSe films due to enhanced carrier separation and transport. The enhanced photoresponse mechanism of the PbSe films through two-step sensitization method was also discussed. These results suggest that the proposed method can be applied to high-performance lead selenide photodetectors. [ABSTRACT FROM AUTHOR]