Preparation and characterization of Al and Mn doped ZnO (ZnO: (Al, Mn)) transparent conducting oxide films
This paper presents the electro-optical, chemical and structural properties of doped-ZnO films deposited by DC-reactive magnetron sputtering at room temperature using the bi-dopant Al and Mn. A minimum resistivity of 3.46×10 -4 Ω cm, exceeding 75.0% average transmittance (380-800 nm), and fundamental band gap of 3.48±0.01 eV have been obtained. XPS analyses show that Zn uniformly remains in the valence state of Zn 2+; all of the Al and a little amount of Mn with valence state of Mn 4+ are supposed to have donor effect, while dominant Mn 2+ will induce to form more oxygen vacancies and this proposal has been verified by O 1 s XPS results. It has been concluded that the presence of more oxygen vacancies will attenuate the effect of hybridization of p- d orbitals in the matrix of ZnO. It has been found that all the as-deposited films have c-axis preferred orientation with flat and smooth surface (RMS surface roughness is of the order of ∼3 nm over 5×5 μm 2 area).