Fundamental Studies of Hydrogen at the Silicon / Silicon Nitride Interface

The quality of the interface between silicon and a dielectric is one of the main influencing parameters for crystalline silicon surface passivation. In this work, this interface is examined by means of capacitance voltage (CV) and nuclear resonance reaction analysis (NRRA) measurements for SiNx:H as well as SiO2 capped SiNx:H passivated p-type float zone silicon samples. Due to a highly sensitive NRRA measurement setup, very small differences in hydrogen concentration at the interface could be detected for the first time and a significant correlation between hydrogen concentration, interface state trap densities Dit and passivation quality is found. The results of this study present easily implementable processes to improve the quality of SiNx:H surface passivation and process stability for solar cell and module production applications. First optimised industrial type Al-BSF p-type cells feature 2 mV and 0.5 mA/cm² gains in Voc and jsc, leading to efficiencies of up to 19.1%