Optimisation of porous silicon based passive optical elements by means of spectroscopic ellipsometry

Abstract

Recently, growing interest in the development of passive optical elements based upon electrochemically etched porous silicon multilayer (PSM) stacks raised the need for efficient control of the preparation. Optimisation of PSM structures experimentally by try and error is, however, troublesome and time consuming. In the present study we demonstrate that spectroscopic ellipsometry (SE) with appropriate optical models can provide the missing feedback for the process engineer for exact design of structural parameters, thereby reducing the efforts for an optimisation cycle. The capabilities of the suggested methodology were experimentally verified on Bragg reflectors and Fabry–Perot interference filters.