Optical and electrical properties of nickel oxide thin films synthesized by sol–gel spin coating

Determination of certain sol-gel growth parameters of nickel oxide films

“…In experimental process, forming of powder micro crystallites on surface of films was seen with increasing molarity above 0.1 M, thus we can conclude that a micro crystallite structure may introduce a decrease in crystallinity. In the literature, as similar to our results, Purushothaman et al [19] also found that increasing dip coating layer number caused an increment in the film crystallinity for 0.15 M NiO films, however Sta et al [7] and Jlassi et al [14] observed that increasing spin layer number caused a decrease in the film crystallinity for 0.5 M NiO films.…”

“…The band gap value of 3.75 eV for 0.05 M NiO films continuously decreases to the values of 3.73 eV, 3.58 eV, 3.52 eV, 3.44 eV and 3.42 eV for 0.07 M, 0.1 M, 0.3 M, 0.5 M and 0.7 M NiO films, respectively. A decrease in E g and transmittance values with molarity may be derived from increasing Ni ions in films [17] and incorporated oxygen atoms replaced interstitial and substitutional sites in the structure [14]. As similar to our study, some researchers [7,14,19] reported that the values of E g for NiO films dropped off with the increasing sol-gel spin and dip coating layer.…”

“…It can be concluded that an increase in the crystallinity with annealing temperature is probably resulted from the complete removal of solvent and water resulting from decomposition Ni (OCOCH 3 ) 2 .4 H 2 O to NiO and increasing annealing temperature can give enough energy to crystallites to direct in a proper equilibrium places [5]. An increment in the crystallinity of NiO with the increasing annealing temperature was also observed in earlier studies [9,14]. The deteriorating crystallinity for 600 1C and 650 1C annealing temperatures can be resulted from the expansion of optical glass substrates.…”

“…[13][14][15][16]. Among these, spin coating is more functional technique owing to its simplicity, safety, low cost and ability to deposit homogenous and good quality films [7,17].…”

“…[18]. In the literature, NiO thin films have been grown as functions of spin layer number [7,14,19], sol-solution pH [20], annealing temperature [4,9,14,21], solvent type [22] and annealing ambient [14] in order to understand the effect of solgel spin coating growth parameters on the features of NiO films. However, according to our best knowledge, there has been no report on the fabrication of NiO film depending on sol-gel precursor solution molarity and there is only one study on effect of solution solvent type.…”