Mid-infrared photoresponse of electrodeposited PbSe thin films by laser processing and sensitization

Abstract Thin films of PbSe semiconductors are important for mid-wave infrared imaging applications. There is a need for a low-cost large-area PbSe thin film deposition process to generate highly sensitive mid-infrared (mid-IR) responsive devices. Here, we report the mid-IR response in the 3 – 5 µm wavelength for PbSe thin films prepared by the electrodeposition process followed by laser processing for densification and sensitization. Scanning electron microscope imaging shows that electrodeposited films consisted of a porous structure having an interconnected particle network. A 1064 nm wavelength pulsed laser, with 50 nanosecond pulse width, was used for homogeneous melting and fast recrystallization of the porous films to convert into planar dense thin films. A comparison of XRD patterns of the as-deposited and laser processed films revealed improvement in PbSe crystallinity with the original crystal structure remaining intact. The electrical resistivity of the laser-sintered films was found to be around 0.027 Ω-cm. The two-step sensitization process of oxidation and iodization increased the final film resistivity to 10.77 Ω-cm and was highly sensitive to mid-IR radiation. The percentage change in film resistance between dark and due to mid-IR exposure of 18.5 mW/cm2 is reported to be 15.9% at an operating voltage of 10 V. Electrodeposition of thin films followed by laser processing can emerge as a viable tool to produce the large-area uniform film for PbSe thin film applications in electronics and photonics devices.