Raman scattering in ZnO thin films doped with Fe, Sb, Al, Ga, and Li

Abstract

Polarized micro-Raman measurements were performed to study the phonon modes of Fe, Sb, Al, Ga, and Li doped ZnO thin films, grown by pulsed-laser deposition on c-plane sapphire substrates. Additional modes at about 277, 511, 583, and 644 cm−1, recently assigned to N incorporation [A. Kaschner et al., Appl. Phys. Lett. 80, 1909 (2002)], were observed for Fe, Sb, and Al doped films, intentionally grown without N. The mode at 277 cm−1 occurs also for Ga doped films. These modes thus cannot be related directly to N incorporation. Instead, we suggest host lattice defects as their origin. Further additional modes at 531, 631, and 720 cm−1 seem specific for the Sb, Ga, and Fe dopants, respectively. Li doped ZnO did not reveal additional modes.

Isotopic study of the nitrogen-related modes in N+-implanted ZnO

“…Therefore, we conclude that, contrary to the suggestion made in Ref. 6, these modes cannot be attributed to intrinsic host lattice defects.…”

“…Therefore, our results suggest that these modes are probably due to localized vibrations associated with local distortions of the lattice caused by nonsubstitutional N or to a complex defect favored by the presence of N. It is worth noting that, in contrast with Ref. 6, we observe these additional modes only in the spectra of the ZnO samples implanted with N + and they are not present in samples implanted with P + or with the native species. Therefore, we conclude that, contrary to the suggestion made in Ref.…”

“…3 Being nitrogen the primary acceptor candidate in ZnO, considerable effort has been devoted to characterize, by means of vibrational spectroscopy, the impurity incorporation and the formation of complexes that may reduce the doping efficiency of N in ZnO. [4][5][6][7] Kaschner et al 5 reported the observation of several additional Raman peaks between 275 and 643 cm −1 in N-doped GaN epitaxial films grown by chemical vapor deposition. They were attributed to local vibrational modes ͑LVMs͒ of N in substitutional O site in the ZnO lattice.…”

“…5 However, Bundesmann et al disputed this interpretation, as they detected similar peaks in ZnO thin films doped with Fe, Sb, and Al, intentionally grown without N incorporation. 6 They attributed the additional Raman peaks to intrinsic host lattice defects. The controversy about the origin of these modes remains, as they have been observed in later works and have been assigned either to LVMs of N ͑Ref.…”

Search for Origin of Room Temperature Ferromagnetism Properties in Ni-Doped ZnO Nanostructure

“…This fact is corroborated from EXAFS result also as discussed earlier. 40,41 . In our case, Raman scattering peak is centred around 580cm -1 for pure ZnO and Ni doping this peak becomes broad and slightly shifted to 583cm -1 .…”