Raman study of doped‐ZnO thin films grown by rf sputtering

Abstract

A Raman spectroscopy study of doped versus undoped ZnO layers is presented. The layers were grown by RF magnetron sputtering and the doping with Al, Sb and Mn was achieved by ion implantation with subsequent annealing. First‐order Raman response measured under λ=488 nm excitation is discussed. It is shown that doping with any of the impurities used in this work produces a strong enhancement of the longitudinal optical (LO) phonon band, which is attributed to the intra‐band Fröhlich mechanism. In addition, doping with Mn results in an extra mode located at 530 cm‐1, tentatively attributed to a local vibrational mode of Mn substituting Zn in the lattice sites. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Resonant Raman scattering in ZnO:Mn and ZnO:Mn:Al thin films grown by RF sputtering

“…Figure 1 shows non-resonant Raman spectra of the studied ZnO, ZnO:Mn and ZnO:Mn:Al samples. They are similar to those reported in our previous work [19]. Vertical lines in figure 1 indicate the positions of the phonon modes previously observed for ZnO and ZnO:Mn.…”

“…The intensity and number of LO phonon lines observed in RRS spectra of ZnO-based materials depend on the grain size, impurities, defects, and free carrier concentration [8]. In a previous work [19] we studied the first-order (non-resonant) Raman response of ZnO films doped with different impurities including Mn. Here we report on our RRS results obtained on low-temperature-grown films of pure ZnO, ZnO:Mn and ZnO:Mn co-doped with Al (ZnO:Mn:Al).…”

Raman study of insulating and conductive ZnO:(Al, Mn) thin films

“…This holds for the MBE‐grown sample, except that (i) there is a mode centered at 330 cm −1 and (ii) the A 1 (LO) mode appears too weak. The prominent feature at 330 cm −1 probably corresponds to the second‐order scattering () and has been observed for both single crystal and polycrystalline samples in various configurations . The low intensity of the allowed A 1 (LO) has also been reported and attributed to the “destructive interference” between the Fröhlich and ODP mechanisms (i.e., a partial cancellation of the matrix elements corresponding to these two mechanisms of electron–phonon coupling) .…”

Raman and Photoluminescence Study of Al,N‐Codoped ZnO Films Deposited at Oxygen‐Rich Conditions by Magnetron Sputtering

“…In ZnO films of poor quality, no one phonon replica can be observed. Generally, the intensity and the number of LO phonon lines observed in resonant Raman spectra of ZnO‐based materials depend on the grain size, impurities, defects, and free carrier concentration . We observed up to 4 LO phonon replicas on resonant Raman spectra (Figure ).…”

“…Generally, the intensity and the number of LO phonon lines observed in resonant Raman spectra of ZnO-based materials depend on the grain size, impurities, defects, and free carrier concentration. [26][27][28] We observed up to 4 LO phonon replicas on resonant Raman spectra (Figure 4). The first 1LO and the second 2LO phonon modes are clearly observed for three samples.…”