Scratch-resistant and optically transparent materials and articles

Embodiments of a scratch-resistant and optically transparent material comprising silicon, aluminum, nitrogen, and optionally oxygen are disclosed. In one or more embodiments, the material exhibits an extinction coefficient (k) at a wavelength of 400 nm of less than about 1×10−3, and an average transmittance of about 80% or greater, over an optical wavelength regime in the range from about 380 nm to about 780 nm, as measured through the material having a thickness of about 0.4 micrometer. In one or more embodiments, the material comprises an intrinsic maximum hardness of about 12 GPa or greater as measured on a major surface of the material having a thickness of about 400 by a Berkovich Indenter Hardness Test along an indentation depth of about 100 nm or greater, low compressive stress and low roughness (Ra). Articles and devices incorporating the material are also disclosed.