Anomalous optical properties of bismuth ultrathin film using spectroscopic ellipsometry in the visible - Ultraviolet range

Kaloari, Ruth Meisye; Widianto, Eri; Dana, I Ketut Agus Putra; Lukmantoro, Arif; Suharyadi, Edi; Kato, Takeshi; Iwata, S.; Absor, Moh. Adhib Ulil; Santoso, Iman

doi:10.1016/j.tsf.2023.139825

Cited by 4 publications

(1 citation statement)

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“…These plots exhibit lower values at lower energies may ascribed to reduced absorption due to modifications in the band structure or the introduction of defect states, while higher values at higher energy regions indicate enhanced absorption arising from additional electronic transitions or band broadening facilitated by the dopant. Furthermore, the highly doped sample (12.5% Cu) showing the lowest value compared to pure PbS indicates a mitigated absorption effect due to the introduction of copper dopants [52]. This could be attributed to altered electronic band structures and reduced optical transitions resulting from the dopant's influence.…”

Section: Optical Propertiesmentioning

confidence: 94%

Investigation of structural, morphological, optical and electronic properties of Cu-doped PbS thin films: a comparative experimental and theoretical study

Ramay,

Aldosary

2024

Phys. Scr.

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Thin film technology has emerged as a cornerstone in optoelectronics, enabling the fabrication of compact, lightweight devices with enhanced performance and efficiency through precise control of the nanoscale thicknesses of functional materials. The current study explores the impact of copper (Cu) doping (3.125%, 6.25%, and 12.5%) on lead (Pb) sites in PbS to examine the structural, morphological, electronic, optical, and thermoelectric characteristics, employing both experimental and theoretical approaches. Polycrystalline thin films of PbS are deposited by spin coating technique on glass substrates. The XRD study discloses the cubic crystal structure of pristine and Cu-doped PbS with nominal variation in d-spacing. Surface morphological investigations reveal that Cu-doping transforms the coffee beans like grains to nanoplates that significantly affect the surface homogeneity and porosity. The tuning of band structure in the visible range, 1.64-2.21 eV is witnessed in the band structure analysis. Moreover, the experimental results are complemented by a theoretical study using WIEN2k software. Theoretical study exhibits the direct bandgap nature and with the incorporation of Cu, it increases from 0.89 to 2.11 eV. The density of states spectra for Cu-doped PbS exhibits strong hybridization between p-states of Pb and S, and d-states of Cu. Optical findings demonstrate significant variations in the absorption spectrum, which result in modifications in the optical energy band gap and peculiar optical parameters of doped samples. At room temperature, the increase in electrical conductivity from 0.2x1020 (Ω.m.s)-1 for PbS to 0.3x1020, 3.1x1020 and 7.8 x1020 (Ω.m.s)-1¬¬, thermal conductivity from 0.25x1014 W/m.K.s to 0.30x1014, 2.4x1014 and 5.2x1014 W/m.K.s and decrease in Seebeck coefficient from 72 to 35, 13 and 8 µV/K with the inclusion of Cu up to 3.125, 6.25 and 12.5% offer the potential for advancing thermoelectric technology. This could lead to improved efficiency and practical utilization in energy harvesting and waste heat recovery.

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Section: Optical Propertiesmentioning

confidence: 94%