Mid-infrared photoluminescence of PbSe film structures up to room temperature

Lead salt materials are of high interest for midinfrared optical emitters and detectors for molecular spectroscopy. The IV-VI narrow gap semiconductors have a multivalley band structure with band extrema at the L point of the Brillioun zone. Due to the favorable mirrorlike band structure, the nonradiative Auger recombination is reduced by one or two orders of magnitude below that of narrow gap III-V and II-VI semiconductor compounds1. The photoluminescence in the midinfrared range for PbSe film structures, excited by a semiconductor laser diode, is investigated. The PbSe films were prepared by Physical Vapor Deposition (PVD) using an electron gun. A PbSe crystal doped with 0.1 at% Bi was used as a source for the fabrication of thin layers. Starting from the assumption that the rate of nucleation is a predominate factor in determining grain size, thin films were fabricated on substrates that had been maintained at various temperatures of deposition process2. Amorphous glass and Kapton polyimide film was used as substrate. The growth rate was 0.2 nm/s. Films were thermally treated at high oxygen pressure in a heated encapsulated system. Microstructure has been studied using XRD, AFM and HRSEM. For PbSe structures photoluminescence at temperature as high as 300 K is demonstrated.