Vacuum Annealing-Induced Modifications in CoCrFeMnNi Thin Films: Surface Morphology, Conductivity, and Work Function

Abstract

The CoCrFeMnNi high-entropy alloy (HEA) thin film has been investigated to understand the impact of vacuum annealing on surface morphology, electrical property, and work function. The thin films were sputtered at room temperature and at 300°C, followed by vacuum annealing at 600°C. Grazing incidence X-ray diffraction analysis demonstrated a transformation from an amorphous to a crystalline structure upon vacuum annealing due to increased thermal energy, accompanied by new MnO peaks. This structural change was corroborated by field-emission scanning electron microscopy, which revealed distinct morphological variations in the films due to MnO formation with increased white spots in H300-A600 and coarser grains. The annealed film lost its conductivity due to oxide formation; however, it gave the highest work function of 4.59 eV. The findings show that vacuum annealing modifies the surface morphology of the thin films by affecting the grain size, electrical properties, and work function compared to as-deposited films. The oxide formation enhanced the thin-film properties and can be used in advanced high-temperature coating applications.