Doping of SrTiO₃ thin films studied by spectroscopic ellipsometry

Abstract
The knowledge of thickness, optical properties and doping profiles of thin film sarnples is essential in view of their application in electronic devices. Here we present spectroellipsometric analysis on metallic oxygen deficient SrTiO₃ thin films grown by pulsed laser deposition on SrTiO₃ substrates. Such rnaterial is very interesting for applications in oxide electronics, having very large dielectric constant in the insulating state and becoming a metal with very high mobility with doping concentration as low as 10¹⁸ e/cm³. First results indicate that SrTiO₃ thin films present a depressed optical absorption in the UV range above the energy gap and an absorption in the infrared region which is enhanced in respect to the bulk material.