A solution growth route to nanocrystalline nickel oxide thin films

• Published in: Applied surface science 2000-10, Vol.165 (4), p.271-278
• Main Authors: Pejova, Biljana, Kocareva, Tanja, Najdoski, Metodija, Grozdanov, Ivan
• Format: Article
• Language: English
• Subjects: Chemical solution method; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in multilayers, nanoscale materials and structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Fullerenes and related materials; Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids); Low-field transport and mobility; piezoresistance; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Nanocrystalline materials; Nickel oxide; Optical band gap; Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity); Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Physics; Semiconductors; Thin solid films
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/S0169-4332(00)00377-9

A chemical route for preparation of NiO thin films on glass substrates from solution containing nickel(2+) ions and urea is presented. The deposition process is based on the fact that urea decomposes to CO 2 and NH 3 by heating at higher temperature. The as-deposited and post-deposition heat-treated materials were characterized by X-ray analysis and FTIR spectroscopy. The results of some optical and electrical measurements made on these films are discussed. X-ray analysis confirmed that as-deposited film is 3Ni(OH) 2·2H 2O, while the post-deposition heat-treated one is nickel oxide with an average crystal size of 13 nm. According to the optical investigations, the absorption coefficient of the deposited material increases upon annealing, the absorption of the annealed films gradually decrease with an increase of the wavelength in the 390–820 nm region. The optical band gap for the post-deposition heat-treated films is 3.6 eV. While the as-deposited thin films are dielectric, the post-deposition treated ones are characterized by resistivity of several MΩs/cm 2 at room temperature.