An x-ray window can include a boron-film 12 and an aluminum-film 52 spanning an aperture 15 of a support-frame 11. The boron-film 12 and the aluminum-film 52 can be the only films, or the primary films, spanning the aperture. The boron-film 12 can include boron and hydrogen. An annular-film 32 can adjoin the support-frame 11, on an opposite side of the support-frame 11 from the boron-film 12. The annular-film 32 can include boron and hydrogen. The annular-film 32 can have the same material composition as, and can be similar in thickness with, the boron-film 12.