Deposition of HfO2 thin films on ZnS substrates

HfO2 thin films with columnar microstructure were deposited directly on ZnS substrates by electron beam evaporation process. SiO2 thin films, deposited by reactive magnetron sputtering, were used as buffer layers, HfO2 thin films of granular microstructure were obtained on SiO2 interlayer by this process. X-ray diffraction patterns demonstrate that the as-deposited HfO2 films are in an amorphous-like state with small amount of crystalline phase while the HfO2 films annealed at 450 °C in O2 for 30 min and in Ar for 150 min underwent a phase transformation from amorphous-like to monoclinic phase. Antireflection effect in certain infrared wave band, such as 3-6 μm, 4-12 μm, 4-8 μm and 3-10 μm, can be observed, which was dependent on the thickness of thin films. The cross-sectional images of HfO2 films, obtained by field emission scanning electron microscopy, revealed that there was no distinct morphological change upon annealing.