. 2021 Jan 15;11:1620. doi: 10.1038/s41598-020-79758-1

Table 2.

Observed room-temperature phonon frequencies of undoped and Cr-doped VO $_{2}$ on c- and r-plane sapphires for thicknesses of 140, 70, 30 and 15 nm⁴⁶.

Raman modes symmetry	VO $_{2}$ c-plane	Cr-doped VO $_{2}$ c-plane	VO $_{2}$ r-plane	Cr-doped VO $_{2}$ r-plane
Raman modes symmetry	140/70/30/15 nm	140/70/30/15 nm	140/70/30/15 nm	140/70/30/15 nm
†	–/–/–/–	122/126/126/129	–/–/–/–	128/135/137/134
B $_{g}$	140/141/141/137	–/–/–/–	139/139/140/140	–/–/–/–
A $_{g}$	193/194/195/195	199/197/197/197	195/195/196/196	201/197/198/194
A $_{g}$	224/224/224/224	224/224/224/222	224/224/225/225	223/222/224/223
B $_{g}$	262/262/263/260	273/273/272/273	262/262/263/–	272/269/271/–
A $_{g}$ /B $_{g}$	308/309/310/309	304/306/305/308	309/308/310/–	304/309/305/301
A $_{g}$ /B $_{g}$	338/339/339/341	340/340/340/341	339/335/336/–	341/–/–/–
A $_{g}$	390/391/391/390/	–/–/–/–	390/386/382/–	–/–/–/–
B $_{g}$	–/–/–/–	394/394/–/–/	396/397/399/–	–/–/401/399
^‡A $_{g}$	435/–/435/–	–/–/–/–	–/–/–/–	438/–/–/–
B $_{g}$	444/443/435/–	446/444/–/–	444/443/–/–	444/–/–/–
B $_{g}$	–/–/–/–	–/–/–/–	–/–/–/–	453/–/–/–
†	–/–/–/–	–/–/–/–	479/477/–/–	–/–/–/–
A $_{g}$	497/496/498/477	501/501/504/–	497/498/491/–	500/495/–/–
A $_{g}$	613/614/615/615	–/–/–/–	616/615/618/619	–/–/–/–
A $_{g}$	–/–/–/–	620/619/–/–	–/–/–/–	–/–/–/–
B $_{g}$	–/–/–/–	646/648/632/630	–/–/–/–	637/626/632/619
⁺A $_{1 g}$ /B $_{g}$	⁺655/660/662/–	–/–/–/–	664/⁺646/–/–	–/–/–/–
B $_{g}$	820/822/820/–	815/812/816/–	822/824/818/–	823/815/816/815

^†Raman mode symmetry not yet assigned in literature; ^‡Raman mode symmetry assigned as A $_{g}$ by Aronov et al.⁵⁶; ⁺Raman mode symmetry assigned as A $_{1 g}$ by Srivastava et al.⁴²; and – no peaks found.