Passivation properties of HfO2-SiO2 Mixed Metal Oxide Thin Films with Low Reflectivity on Silicon Substrates for Semiconductor Devices

• HfO2-SiO2 mixed metal oxide based thin films were introduced. • HfO2-SiO2 based thin films reduce reflectivity of a silicon surface. • Silicon surface can be passivated by HfO2-SiO2 mixed metal oxide based thin films. • Crystalline properties of the films may have a role in the passivation effect. • Post-annealing effects the reflectance and passivation properties of the films. HfO 2 -SiO 2 mixed oxide-based thin films were introduced in this work, and their passivation and anti-reflection properties were examined by using carrier lifetime, x-ray diffraction, scanning electron microscope, energy dispersive x-ray analysis, reflectance, and Fourier transform infrared measurements. The HfO 2 -SiO 2 mixed oxide solutions were prepared with different composition ratios, and the thin films were formed on p-type CZ-Si substrates using the spin-coating technique. Annealing of the samples was carried out in ambient air at different temperatures after optimizing the solution ratio. When annealed at 600 and 700°C, the average reflectance of the samples was observed to be around 15% in the spectral range of 300-1000 nm, with a minimum reflectance point lying in the visible range. The effective carrier lifetimes increased up to 32 μs after annealing at 600°C compared to the initial lifetime of around 2 μs. Annealing at higher temperatures significantly decreased the carrier lifetimes (4.5 and 0.6 μs for 700 and 800°C, respectively). The results of this study revealed that the HfO 2 -SiO 2 mixed oxide films can provide a good passivation effect in addition to an effective anti-reflection property depending on the annealing temperature.