Substitutional Sulfur in CdSe: Localized Vibrational Modes

Abstract

The substitutional sulfur at the selen site in wurtzite CdSe is identified by a combination of infrared absorption spectroscopy and first principles calculations. The dominant normalS32 isotope gives rise to two local vibrational modes at 270.6 and 271.4 cm−1 (10 K) assigned to the nondegenerate A1 and the twofold degenerate E representations of the C3v point group. The corresponding signals of the normalS34 isotope occur at 263.6 and 264.4 cm−1. The results of measurements performed on a set of samples supplied by different manufacturers highlight that sulfur is an ubiquitous impurity in CdSe unintentionally incorporated into the crystals during the process of growth.

Vibrational Signatures of Substitutional Oxygen in CdTe and CdSe

“…For example, LVMs of substitutional S, Be, Mg, and Ca in zinc-blende CdTe and ZnTe as well as S, Be, and Mg in wurtzite CdSe were already reported. [15][16][17][18] Oxygen possesses three stable isotopes-the predominant 16 O one (99.76%) and two other isotopes with very low natural abundances of 0.2% ( 18 O) and 0.04% ( 17 O), which provides the possibility for an unambiguous identification of oxygen-related defects via their isotopic LVM signatures.…”