The ellipsometric characterizations of amorphous beryllium nitride (a-Be3N2) thin films deposited on Si (1 0 0) and quartz at temperature < 50 degrees C using reactive RF sputtering deposition were examined in the wavelength range 280-1600 nm. X-ray diffraction of the films showed no structure, suggesting the Be3N2 films grown on the substrates are amorphous. The composition and chemical structures of the amorphous thin films were determined by using electron spectroscopy for chemical analysis. The surface morphology of a-Be3N2 was characterized by atomic force microscopy. The thicknesses and optical constants of the films were derived from spectroscopic ellipsometry measurements. The variation of the optical constants with thickness of the deposited films has been investigated. From the angle dependence of the polarized reflectivity we deduced a Brewster angle of 64 degrees. At any angle of incidence, the a-Be3N2 shown high transmissivity (80-99%) and low reflectivity (<18%) in the visible and near infrared regions. Hence, the a-Be3N2 could be a good candidate for antireflection optical coatings under conditions of optimized the type of polarization and the angle of incidence. (C) 2009 Elsevier B.V. All rights reserved.