Tuning of structural, optical band gap, and electrical properties of room-temperature-grown epitaxial thin films through the Fe2O3:NiO ratio

Abstract

We have investigated the structural, optical band gap, and electrical properties of (Fe 2 O 3 ) 0.5 x :(NiO) 1 − 0.5 x ( x = 0.3, 0.4, 0.5, 0.6 and 0.7) epitaxial thin films grown on an atomically smooth substrate at room temperature. With increasing Fe 2 O 3 content, the rock-salt structure of the thin films transformed to a spinel structure above x = 0.6. In terms of the local structure, the increased ratio of Fe 2+ ions to Fe 3+ ions indicates that the octahedral sites of FeO were continuously transformed into distorted octahedral and tetrahedral sites. On the other hand, the NiO matrix was not affected by the local structure change. Chemical composition of Fe 2 O 3 :NiO affected the crystal structure, the electrical conductivity and the optical band gap of direct transition (3.35 to 2.99 eV).

Facile synthesis of Ni/NiO nanocomposites: the effect of Ni content in NiO upon the oxygen evolution reaction within alkaline media

“…This is consistent with literature reports and the introduction of metallic Ni atoms reduce the bandgap associated with NiO, thus increase the charge transfer rate between electrode and electrolyte. 35 …”

Synergistically enhanced solar light‐driven degradation of hazardous food colorants by ultrasonically derived MgFe2O4/S‐doped g‐C3N4 nanocomposite: A Z‐scheme system‐based heterojunction approach

“…As represented, the band gap values were noted by extrapolating the linear portion of the graph between (αhν) 2 and hν. [ 115 ] The predicted band gap values were found to be 1.89, 2.03, 2.19, 2.32, 2.41, 2.60, and 2.71 for MFO, MFO:CNNS (1:1), MFO:SCNNS (2:1), MFO:SCNNS (1:1), MFO:SCNNS (1:2), SCNNS, and CNNS, respectively. It has been noted that the band gap of the CNNS gets reduced by the inclusion of S‐dopant.…”

“…As represented, the band gap values were noted by extrapolating the linear portion of the graph between (αhν) 2 and hν. [115] The predicted band gap values were found to be 1. This implies that the addition of S atom resulted in enhancement in the visible light absorbing power of carbon nitride matrix.…”

The Synthesis Methods of Nickel Oxide Nanostructures - A Brief Review

“…NiO is also considered a potential candidate for application in smart windows, drug delivery and MRI agent [9][10]. Bulk NiO adopts a rock salt structure and it is a p-type semiconductor with a wide band gap in the range of 3.6-4.0 eV [11]. Nanostructured NiO exhibits electronic, dielectric behavior and high reversible capability because of quantum size confinement and high surface energy.…”