Sol–gel preparation and optical characterization of NiO and Ni1−xZnxO thin films
2003; Elsevier BV; Volume: 258; Issue: 3-4 Linguagem: Inglês
10.1016/s0022-0248(03)01560-4
ISSN1873-5002
AutoresYoung Ran Park, Kwang Joo Kim,
Tópico(s)Copper-based nanomaterials and applications
ResumoNiO and Ni1−xZnxO thin films have been prepared on Al2O3(0 0 0 1) substrates by a sol–gel method using nickel and zinc acetates as precursors. Polycrystalline films were obtained by spin-coating the precursor solutions followed by annealing in air in the 300–900°C range with the best crystalline quality being achieved near 800°C. For Ni1−xZnxO (x⩽0.31) films the cubic lattice constant is found to increase linearly with the Zn composition. The optical constants of the NiO and Ni1−xZnxO films have been obtained by spectroscopic ellipsometry in the 2.0–4.5 eV photon energy region. The optical band gap due to a charge-transfer transition between the O p-like bands and the Ni d-like bands is found to decrease with increasing Zn composition from that of NiO (3.65 eV). A new absorption structure is observed for Ni1−xZnxO below the band-gap edge. It is attributable to transition between the O p-like bands and the Zn s-like bands, created inside the band gap by the Zn substitution.
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