Influence of Low Molarity Hafnium Synthesis on the Reflection Properties of Polished and Textured Crystalline Silicon Substrates Coated with HfO2 Thin Films

HfO2 thin films formed with prepared low molarity (0.05 M) HfO2 solution were investigated using the spin coating method. Effects of annealing time and coating speed on reflection properties were examined. Thin films were formed both on flat and textured crystalline silicon (c-Si) surfaces. The average reflectance (350-1000 nm) was reduced on coated flat c-Si from approximately 36% (uncoated control surface) to 11.60%. However, it was observed that the surface of texture-c-Si is not fully covered with the film and the film was in fiber-like mesh structure on the surface. Additionally, to provide full coating on the texture and flat Si surface, solutions in different molarities were prepared and coated on the flat and textured c-Si surface. Observed results present the mesh structure of the film coated on flat silicon surface with low hafnium molarity (0.05 M) in the solution and has antireflective effect towards the incoming illumination. However, morphological and optical properties of the flat and textured silicon surfaces differ significantly depending on the hafnium synthesis.