Role of starting material composition in interfacial damage morphology of Hafnia211 Silica multilayer coatings

摘要

Flat bottom pits, previously shown to be unstable above a critical fluence, may211u001ebe impacted by interfacial characteristics of the multilayer. TEM cross-sections 211u001ereveal multilayer coatings deposited from hafnium have fewer interfacial voids 211u001ethan those deposited from hafnia. To correlate this reduction with the occurrence 211u001eof flat bottom pits, multilayer high reflectors deposited by reactive electron-211u001ebeam evaporation from both metallic and oxide sources were damage tested with 3-211u001ens, 1064-nm pulses. To shift the electric-field peaks to the adjacent interface, 211u001ehalf of the samples included an additional buried half-wave of silica in their 211u001eall quarter-wave design. All quarter-wave reflectors deposited from hafnia had 211u001eflat bottom pit damage in the outer six layers at fluences of 20J/cm(2). 211u001eInterfacial damage also occurred in hafnium deposited coatings at fluences as low 211u001eas 20J/cm2, but at significantly different depths. The only interfacial damage 211u001eobserved on the all quarter-wave coatings was at the substrate multilayer 211u001einterface. Flat bottom pits were observed in the buried half-wave coatings with a 211u001ecorrelation to electric-field position and preference to interface type.