A method for forming boron (B) containing Al2O3 composite layers includes (a) reacting a substrate surface with an aluminum-containing precursor to form a first monolayer, (b) purging excess aluminum-containing precursor and reaction by-product, (c) reacting the first monolayer with a second precursor, and (d) purging excess second precursor and reaction by-product, such that steps (a) to (d) constitute one cycle, the composite layers being formed after a plurality of cycles, and the resultant composite layers have a chemical formula of BxAl2−xO3, where x varies in the range of 0 and 2.