Optical Constants of As-grown and RTA GaAs1-xNx Layers Analysed by Spectroscopic Ellipsometry

In this work, we propose, for the first time, an analysis of the rapid thermal annealing (RTA) effect on GaAs_1-xN_x layers using spectroscopic ellipsometry (SE) on a set of as-grown and RTA GaAs_1-xN_x (x=0.1%, 0.5% and 1.5%) samples. This material being dedicated to several optoelectronic applications, an accurate knowledge of its optical properties is required to improve the selection of the layer thickness in a device system. The complex refractive indices are accurately determined, and the RTA effect on the samples is deduced. We have found that post-growth treatment (RTA) affects more samples with high nitrogen content, leading to an improvement of the optical constants. In addition, RTA is found to decrease the E₁ transition energy nitrogen blue-shift.