Development of Porous Antireflective Films on Borosilicate Glasses

Experiments were conducted to characterize the development of gradient-index antireflective (GIAR) films formed on a phase-separated alkali borosilicate glass. Solution chemistry, secondary-ion mass spectrometry, Auger electron spectroscopy, weight-loss, scanning electron microscopy, and specific surface area analyses were used to evaluate a proposed model for film formation. The results suggest that the film-forming process is more complicated than proposed. For near-optimum heat trcatments, the film-formation acid treatment was virtually nonselective; only for much longer than optimum annealing times was selectivity evident. The graded-index films may result from precipitation of dissolved glass. The analyses were complicated by major compositional variations existing in the as-received glass.