MgF2/BN double layer antireflection coating for photovoltaic application

Modeling and fabrication of double layer MgF2/BN antireflection coatings have been undertaken. Minimal reflection losses (≪5%) over a wide range of the solar irradiance (1.1 to 3 eV) are realized for Si and GaAs. Dispersion (n,k) analyses of individual BN films using spectroscopic ellipsometry indicated a nearly constant index of refraction of ∼ 2.8 and a negligible transmission loss over the useful range of the solar spectrum (0.7 to 3.2 eV). This spectral stability in conjunction with its robust ceramic nature and its fairly wide bandgap (6.2 eV) makes BN thin film well adapted for integration in multi-junction and space solar cells.