Surface and Morphological evolution of multilayer ultraviolet coatings developed by reactive electron beam deposition process

摘要

Development of stable multilayer coatings for ultraviolet region of electromagnetic spectrum is a very challenging task due to the constraints of availability of suitable optical thin film materials. Besides the spectral performance of such devices are limited by the over all topographies evolved both during the growth and post-growth stages. In the present work, multimode scanning probe microscope has been employed to study the surface morphological evolution of ultraviolet multilayer coatings developed for various excimer laser wavelengths. These ultraviolet multilayer coatings consist of alternate layers of Gadolinium oxide and Silicon dioxide films and have been developed through reactive electron beam evaporation technique: Surface topography, force modulation and force spectroscopic measurements have been carried out on these coatings to investigate their opto-mechanical properties. These measurements have been carried out at two different occasions with a time span of 18 months, were intended to probe the multilayer stability over the period of time. Spectrophotometric measurements have also been carried out on these multilayers in order to observe their spectral stability. Both the measurements have been shown excellent correlation. Some interesting results of both multimode scanning probe microscopy and Spectrophotometric measurements and analysis have been presented in this paper.