Study of vibrational properties of Bi 2 − x Mn x Te 3 nanocrystals in host glass: Effect of xMn‐concentration

• Published in: Journal of Raman spectroscopy 2022-01, Vol.53 (1), p.95-103
• Main Authors: dos Santos Silva, Alessandra, Guimarães, Éder Vinícius, Cano, Nilo Francisco, da Silva, Ricardo Souza
• Format: Article
• Language: English
• ISSN: 0377-0486; 1097-4555
• DOI: 10.1002/jrs.6255

The Raman and infrared (IR) active lattice vibrations of xMn‐concentration Bi 2 − x Mn x Te 3 nanocrystals (NCs) as a dopant in semiconductor Bi 2 Te 3 nanocrystals grown in a host glass matrix, whose symmetries correspond to the space group, are investigated by Raman scattering. Transmission electron microscopy images confirm the formation of Bi 2 − x Mn x Te 3 nanocrystals with an average size of around 5.4 nm. The observation of the six hyperfine structure lines in electron paramagnetic resonance spectra confirms the incorporation of Mn 2+ ions in Bi 2 Te 3 nanocrystals. The vibrational modes of quintuple layer (QL) of the diluted magnetic semiconductor Bi 2 − x Mn x Te 3 nanocrystals are modified in relation to pure Bi 2 Te 3 nanocrystals. The appearance of the (95.5 cm −1 ), (114 cm −1 ), and (103 cm −1 ) IR‐active modes is mainly due to quantum size effects. Indeed, the redshifts of the (95.5 cm −1 ), (103 cm −1 ), (110 cm −1 ), (114 cm −1 ), and (141 cm −1 ) vibrational modes give strong indications of the substitutional and interstitial incorporation of Mn 2+ in the Bi 2 Te 3 crystalline structure. In addition, the Raman spectra show the formation of Bi 2 OTe 2 semiconductor due to the appearance of the (123 cm −1 ) mode. The investigation of the Bi 2 − x Mn x Te 3 nanocrystal has promising potential to design new devices with magnetic and optical properties adjusted according to the xMn‐concentration.