Amorphous Ge-As-Te thin films prepared by pulsed laser deposition: A photostability study

Pulsed laser deposition was used for the fabrication of amorphous thin films from Ge-As-Te system with the aim to study their intrinsic photostability. Photostability of prepared layers was studied using spectroscopic ellipsometry within as-deposited as well as relaxed layers. For irradiation, laser sources operating at three energies (1.17, 0.92 and 0.8 eV) in band gap region of the studied materials were employed. The lowest values of photorefraction (refractive index changes) accompanied with lowest changes of band gap values present Ge20As20Te60 thin films, which are therefore considered as the layers with highest photostability, especially in relaxed state.