Structural, Optical and Electrical Properties of NiO Thin Films Prepared by Low Cost Spray Pyrolysis Technique

Abstract

Nickel Oxide (NiO) thin films are fabricated using fresh and aged precursor solutions using a low cost simplified spray pyrolysis technique. Structural, optical and electrical properties of two different films were studied. The structural studies show that the film prepared from the aged solution has more grain size (60.3nm) than the film prepared by fresh solution (21nm). From the optical studies it is found that, the band gap of film from fresh solution have 3.6eV while the band gap of film from aged solution is about 3.5eV. The refractive index (n) is measured with the help of PUMA software and for the film from fresh solution it remains at 1.95 through visible region. However, for the film from aged solution, it varies from 2 to 1.78 in visible region. The calculated extinction coefficient (k) values of the films show no significant variation in visible and NIR range. The electrical studies confirm that the grown films are p- type. The resistivity measured for two films shows that the resistivity is low (2.271×10 2 Ω cm) for the film prepared by fresh solution and it is high (2.725×10 2 Ω cm) for the other one. 