Temperature-induced PbS quantum dots with tunable broadband wavelength grown by atomic layer deposition

Lead sulfide (PbS) quantum dots (QDs) were deposited onto silica substrates by atomic layer deposition (ALD). By controlling the number of growth cycles, the average size of the PbS nanocrystals (NCs) changed from approximately 6.3 to 95.4 nm. The crystalline phase of the PbS semiconductor materials was investigated via X-ray diffraction, and it was established that as the size of the NCs increased, the preferred growth orientation of the PbS films was (200). The obtained nanofilms were compact and continuous polycrystalline films with well-defined grain boundaries. To control the size of PbS QDs further, the temperature-induced characteristics of the ALD-fabricated PbS QD films were studied through annealing. Slow growth of the PbS QDs was observed for the nanofilms annealed at temperatures below 300 degrees C, whereas the QD size increased significantly at annealing temperatures above 300 degrees C. The broad near-infrared luminescence wavelength of the PbS nanofilms was tuned from 1000 to 1600 nm. Moreover, the photoluminescence lifetime of the annealed PbS QDs increased from 4.96 to 10.92 mu s. The temperature-induced and size-controlled PbS QDs are ideal materials for application in wavelength-tunable optical devices.

Automated summary

Lead sulfide (PbS) quantum dots were deposited on silica substrates by atomic layer deposition (ALD) to control their size. The size-controlled PbS QDs showed changes in growth orientation as the size of nanocrystals increased, with enhanced near-infrared luminescence and increased photoluminescence lifetime. The temperature-induced characteristics of the ALD-fabricated PbS QD films were also studied through annealing, showing different growth behaviors at different temperatures.