Electronic properties of negatively charged SiOx films deposited by Atmospheric Pressure Plasma Liquid Deposition for surface passivation of p-type c-Si solar cells

• The passivation mechanism relies strongly on the post-deposition firing temperature.
• Increase in silanol concentration enhances the field effect passivation quality.
• Increase in carbon concentration deteriorates the chemical passivation quality.
• Conductance measurements reveals near interface traps due to traces of carbon.
• Dielectric constant is two times higher for films fired at 810 °C compared to 940 °C.

Here we demonstrate the influence of firing temperatures on the electronic properties of Atmospheric Pressure Plasma Liquid Deposition (APPLD) silicon dioxide films due to reformed material composition and its overall impact on surface passivation quality. Experimentally extracted electronic parameters using electrical capacitance-voltage-conductance (C-V-G) measurements on a Metal-Oxide-Semiconductor (MOS) structure reveal that films fired at 810 °C show a slightly higher concentration of negative fixed charges (− Qf) and interface trap charges (Dit) compared to films fired at 940 °C. Such a dependency on the firing temperature can be attributed to variation in the net concentrations of silanol and carbon groups within the films, subsequently influencing the type of passivation mechanism involved. We show that for films fired at 810 and 940 °C, the predominant passivation mechanisms are related to field effect induced by excess silanol groups and chemical passivation due to the absence of electrically active carbon related defects, respectively. Additionally, dielectric constant (K) extraction from C-V measurements at 1 kHz returns an almost 2-fold higher K-value for films fired at 810 °C (K ~ 21) compared to films fired at 940 °C (K ~ 12), due to excess silanol concentration in the former films.