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

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 NixMn3−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.