Structural and Optical Properties of Zn1-XCoXO Thin Films Fabricated by Laser Molecular Beam Epitaxy
Zn1-xCoxO thin films on sapphire (0001) substrates were synthesized by laser molecular beam epitaxy (LMBE) method at various temperatures under a work ambient pressure of 5.0 x 10-5 Pa condition. X-ray diffraction (XRD) spectra, UV–visible transmission spectra and X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra were employed to characterize the properties of samples. All samples were of wurtzite hexagonal structure with the preferential c-axis-orientation. Co2+ ions incorporated into ZnO lattice and substituted for Zn2+ ions. ZnLMM Auger spectrum implied Zn interstitials existed in sample. The optical transmission of all samples was relatively high in visible region. Two PL emission peaks located at 418 nm and 490 nm were assigned to the electron transition from the Zn interstitials to the top of the valence band and from the Zn interstitials to the Zn vacancies, respectively.
Pengcheng Wang, Liqun Ai, Yungang Li, Xiaoming Sang and Jinglong Bu
J. Z. Yang et al., "Structural and Optical Properties of Zn1-XCoXO Thin Films Fabricated by Laser Molecular Beam Epitaxy", Advanced Materials Research, Vols. 295-297, pp. 1958-1963, 2011