Low temperature Raman study on the site symmetry of ZnSe:P

Raman spectra of phosphorous doped ZnSe are recorded from 9 to 300 K. In addition to TO mode at 208 cm−1 and LO mode at 253 cm−1, a new mode around 240 cm−1 is observed between 55 and 270 K. The spectra at lower and higher temperatures do not show the new mode. This new mode confirms that there is a reduction of (Se site) symmetry from T d to C 3 v when P substitutes for Se. This is due to Jahn Teller distortion.