Open AccessSpectroscopic ellipsometry study of the Zn3N2 films prepared by radio-frequency sputtering
Author(s) -
Rengang Chen,
Jinxiang Deng,
Chen Liang,
Le Kong,
Cui Min,
Xuefei Gao,
Pang Tian-Qi,
Miao Yi-Ming
Publication year - 2014
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.63.137701
Subject(s) - materials science , thin film , ellipsometry , refractive index , crystallite , band gap , analytical chemistry (journal) , substrate (aquarium) , sputtering , sputter deposition , molar absorptivity , optics , grain size , optoelectronics , composite material , chemistry , nanotechnology , oceanography , physics , chromatography , geology , metallurgy
Zinc nitride (Zn3N2) thin films were deposited on glass substrates by reactive radio-frequency magnetron sputtering from a pure Zn target in nitrogen-argon ambient. X-ray diffraction analysis indicates that the films just after the deposition are polycrystalline with a preferred orientation of (400). With increasing substrate temperature, the grain size in zinc nitride film increases from 26.5 nm (100 ℃) to 33.6 nm (200 ℃), and then decreases to 17.8 nm (300℃). Atomic force microscopy reveals that the film surface morphology is dependent on the substrate temperature. With reflective spectroscopic ellipsometry, the ellipsometric parameters ψ and Δ of Zn3N2 films are measured. Then, a new model for Zn3N2 films is built. With the Tauc-Lorentz dispersion formula, the ellipsometric data are fitted, and both the thickness and optical constants (refractive index and extinction coefficient) of the films are obtained at a wavelength of 430–850 nm. The optical band gap is calculated from the extinction coefficient by using the Tauc formula, and a direct band gap of 1.73–1.79 eV is obtained.