@article{0b12963d7a264b60842d710e4b07b98d,
title = "On the origin of an additional Raman mode at 275 cm -1 in N-doped ZnO thin films",
abstract = "A systematic investigation on the optical properties of N-doped ZnO thin films was performed in order to understand the origin of an additional Raman mode at 275 cm -1. This Raman peak was observable only at N 2 pressures lower than 30 Pa during pulsed laser deposition. Its intensity decreased with an increase of N 2 pressures and eventually vanished at pressures above 30 Pa. N substitution of O (N O) was identified by photoluminescence and x-ray photoelectron spectroscopy and correlated well with the Raman intensity. The electrical measurements showed significant changes in resistivity, charge carrier concentration, and mobility due to the presence of N acceptors. Investigations on undoped ZnO films grown in Ar without N 2 further confirm that N doping plays a key role in the Raman scattering. The experimental data indicate that the Raman mode originates from N O related complexes, likely in the form of Zn i-N O. These investigations help to understand the doping mechanisms and underlying physics of the additional Raman mode in the ZnO films.",
author = "Keyue Wu and Qingqing Fang and Weina Wang and Thomas, \{M. Allan\} and Jingbiao Cui",
note = "Funding Information: This work was supported by Research Foundation for the Doctoral Program of High Education of China (Grant No. 20093401110004), Science Foundation of Anhui Province (Grant No. 090414177), Project of West Anhui University commissioned by Lu{\textquoteright}an (Grant No. 2009LW027), and the National Science Foundation under Award No. EPS-1003970. Keyue Wu gratefully acknowledges the scholarship support from the Chinese Scholarship Council. FIG. 1. SEM images of ZnO thin films grown under 10 and 50 Pa nitrogen pressures. FIG. 2. XRD patterns of the samples ZO-10 Pa and ZO-50 Pa. Inset shows the XRD rocking curves of the two samples. FIG. 3. Raman spectra of N-doped ZnO films grown at different nitrogen pressures. FIG. 4. (a) Optical transmission spectra of N-doped ZnO films grown at different N 2 pressures. (b) The Tauc plots for the N-doped ZnO films. FIG. 5. Room temperature PL spectra of N-doped ZnO films grown at N 2 pressures of 10 and 50 Pa, respectively. The dashed lines in the inset are Gaussian fits to the experimental data of sample ZO-10 Pa. FIG. 6. Temperature dependent PL spectra of the sample deposited at 10Pa. Note that the peaks labeled by stars are noise. FIG. 7. Temperature dependent PL spectra of the N-doped ZnO thin film deposited at 50 Pa of N 2 . The inset shows the Gaussian fits to the experimental spectrum measured at 10 K. FIG. 8. XPS spectra of ZnO films grown under different N 2 pressures. The blue curves are fits to the experimental data. FIG. 9. Raman spectra of ZnO films deposited at 2, 15, and 50 Pa of Ar. The data from ZnO film grown at 2 Pa of N 2 is included for comparison. FIG. 10. Electrical resistivity, charge carrier concentration, and mobility as a function of N 2 pressure during deposition for the N-doped ZnO films. ",
year = "2012",
month = mar,
day = "15",
doi = "10.1063/1.3697971",
language = "English",
volume = "111",
journal = "Journal of Applied Physics",
issn = "0021-8979",
number = "6",
}