Epitaxial growth of wafer-scale PbS single-crystal films for room-temperature near-infrared sensing

The rapid advancement of the Internet of Things has underscored the importance of advanced photodetection technologies, particularly for near-infrared (NIR) sensing and imaging. However, conventional materials such as InGaAs, and HgCdTe face significant challenges, such as complex fabrication with high costs and limited room-temperature NIR sensitivity. Here, we report the chemical vapor deposition (CVD)-driven epitaxial growth of wafer scale lead sulfide (PbS) single-crystal films on SrTiO₃ (STO) substrates. The single-crystal films exhibit exceptional crystallinity with highly oriented domains alignment. By constructing an asymmetric Au-Cr/PbS/InZnO (IZO) structures, the devices were enabled with efficient photoresponse. The Schottky contact not only induces a substantial photovoltage under infrared light, breaking through the cryogenic operation limitation of traditional Pb-based devices, but also leads to sub-millisecond response (τ_rise/τ_fall = 0.57/0.68 ms). Through the synergistic integration of the high-quality single-crystalline film with the asymmetric interfacial engineering, we achieve room-temperature, zero-bias infrared imaging. As a result, the devices exhibit a specific detectivity D* of 9.8 × 10¹⁰ cm Hz^1/2 W^-1, offering a scalable pathway toward low-cost, uncooled infrared imaging systems and demonstrating significant potential for practical applications.