Surface morphological and optoelectrical characteristics of silicon nitride featured with magnesium oxide nano coating

The silicon nitride (Si 3 N 4 ) solar cell is well-known for its use in solar energy applications due to its passivation properties, which minimize surface recombination, improve thermal stability, and enhance chemical resistance. However, Si 3 N 4 is found to increase processing complexity due to uneven particle dispersion, and a higher concentration of Si 3 N 4 leads to microcracks in areas of high stress concentration, which limit the optoelectrical properties. This research aims to overcome processing difficulties and to enrich the functional characteristics of Si 3 N 4 solar cells with 20, 30, and 40 nm of magnesium oxide (MgO) nanocoating via a vacuum-assisted chemical vapour deposition (CVD) process. The effects of MgO and vacuum on the surface morphology during the CVD process were analyzed, revealing a fine-grain structure without microcracks, resulting in enhanced optoelectrical properties compared to those of the monolithic Si 3 N 4 solar cell. Likewise, X-ray diffraction analysis confirms the presence of MgO in Si 3 N 4 and its crystalline size. Furthermore, the Si 3 N 4 layer with 40 nm MgO is found to have an optimum drain current density of 2.8 × 10 −3 A, an improved photocurrent density of 2.6 mA/cm 2 , a reduced transmittance of 58 %, and a superior solar conversion efficiency of 24.1 %. It is suitable for thin-film solar cell applications.