Ga-Ge-Te amorphous thin films fabricated by pulsed laser deposition

► Pulsed laser deposition was used for fabrication of amorphous Ga-Ge-Te thin films. ► GeTe4, eventually GaTe4 tetrahedra and disordered Te chains form the film structure. ► Optical functions of Ge-Ga-Te films were characterized by spectroscopic ellipsometry. ► All as-deposited Ga-Ge-Te thin films are stable against 1550 nm irradiation. ► In annealed state, the most photostable composition seems to be Ga10Ge15Te75.