Using spectroscopic ellipsometry for the characterisation of thin films for advanced photovoltaic concepts

Highly developed and sophisticated production techniques of modern solar cells with functional optical elements show the need for a quick, precise, cost effective and operator-friendly characterisation technique. Variable Angle Spectroscopic Ellipsometry (VASE) can fulfil this task. Even though well established for a range of known materials, the application to new materials isn't always straightforward. Since VASE is based on an iterative modelling process by optimisation of some figures of merit, there is a lot of experimental work to do to prove assumptions about the sample which must be made beforehand. In this work, we correlate PECVD deposition parameters with VASE model parameters and certain features of hydrogenated amorphous silicon carbide (a-SixC1-x:H). a-SixC1-x:H is a very versatile material that can be adapted to a very wide range of concepts to enhance the efficiency of silicon solar cells. To prove this, we show the production of a Bragg filter consisting of ten alternating layers of this material.