SO4 in Cadmium Chalcogenides: CdSe versus CdTe

• Published in: physica status solidi (b) Vol. 259; no. 7
• Main Authors: Herklotz, Frank, Lavrov, Eduard V., Melnikov, Vladlen V.
• Format: Journal Article
• Language: English
• Published: 01.07.2022
• Subjects: CdSe; CdTe; oxygen; sulfur sulfur–oxygen complex, vacancy–impurity complexes, vibrational spectra
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.202200029

A study combining infrared (IR) absorption spectroscopy and first‐principles theory is presented for a sulfur–oxygen complex in CdSe characterized by IR absorption lines located at 1094, 1107, and 1126 cm−1 (10 K). The properties of the center are compared to a similar species occurring in CdTe that gives rise to two absorption lines at 1097 and 1108 cm−1 (10 K). Temperature‐ and polarization‐sensitive measurements performed on 18O‐enriched samples reveal that for both materials the IR absorption lines are due to split ν3 stretch vibrations of a distorted sulfate (SO4) tetrahedron, whereby the local point group of the SO4 complex is reduced to Cs and C3v in hexagonal CdSe and cubic CdTe, respectively. Measurements on the vibrational spectrum of the sulfate species in the spectral range of symmetric stretch (ν1), bend (ν4), and combination modes (ν1+ν3) are presented. The cation vacancy VCd is discussed as a likely site occupied by SO4 in CdSe. Infrared (IR) absorption spectroscopy and first‐principles calculations on a sulfur–oxygen complex in CdSe, characterized by IR absorption lines at 1094, 1107, and 1126 cm−1 (10 K), identify the center as a distorted sulfate (SO4) tetrahedron, likely occupying cadmium vacancy sites. The properties of the complex are compared to a similar species occurring in CdTe.