Liquid flow deposited spinel (Ni,Mn)₃O₄ thin films for microbolometer applications

Highlights: • Highly quality (Ni,Mn)₃O₄ thin films were grown using liquid flow deposited (LFD) technique. • It is possible to deposit multi–component manganite–oxide thin films by LFD at low temperatures. • Nickel–manganite films showed a good negative temperature coefficient (NTC) characteristic. • Liquid flow deposited (Ni,Mn)₃O₄ thin films are very potential for microbolometer applications. - Abstract: A liquid flow deposition (LFD) technique was initially used for the fabrication of single-component Mn₃O₄ thin films onto Si wafer substrates at a range of substrate temperatures of 30–80 °C, with the introduction of an oxidizing reagent (H₂O₂). As a result, solid thin films were well formed from an aqueous solution. An X-ray diffraction (XRD) analysis showed typical characteristics of hausmannite Mn₃O₄ with a spinel tetragonal phase. Field-emission scanning electron microscopy (FE-SEM) observations revealed nano-sized grains arranged uniformly on a dense and smooth surface for all of the as-deposited films. On the other hand, the LFD method was then extended to prepare two-component nickel–manganite films according to the binary chemical composition of Ni_xMn_3−xO₄ with x = 0.02–0.2. The as-grown nickel–manganite films showed a surface with a good quality with a spherical bead-like architecture when x ≤ 0.10, while a conversion from spherical grains into highly porous nanowalls in the microstructure was noted in films when x ≥ 0.12. These results signify that it is possible to fabricate various multi-component manganite-oxide thin films at a low temperature. In addition, the dependences of the room-temperature electrical resistivity (ρ) and the temperature coefficient of resistance (TCR) on the Ni substitution level (x) were investigated on films annealed at 400 °C