On the optical properties of amorphous Ge–Ga–Se films prepared by pulsed laser deposition

Annealing effects on the structure and optical properties of GeSe2 and GeSe4 films prepared by PLD

“…This discrepancy can be probably explained by the different state of as-deposited amorphous films prepared using different techniques. Němec et al reported the decrease of index of refraction and the increase of optical band gap of the Ge-Ga-Se films prepared by PLD induced by annealing [25], which is consistent with our results. But thermalexpansion up to 5.4% was found in Ge-Ga-Se films.…”

“…The broad vibrating band (235-330 cm −1 ) with three maxima near 250, 267 and 310 cm −1 on the Raman spectra of studied samples can be assigned to the chalcogen-chalcogen stretching vibration mode at the edges of large clusters (250 cm −1 ), the A 1 vibration modes of Se chains (267 cm −1 ) and F 2 antisymmetric vibration modes of GeSe 4/2 based structural units (310 cm −1 ) [25].…”

“…The main band near 197 cm −1 should be assigned to the A 1 vibration modes of the corner-sharing GeSe 4/2 tetrahedra [27]. The companion peak near 213 cm −1 can probably be assigned to the A c1 breathing vibrations of edge-shared Ge 2 Se 8/2 bi-tetrahedra [25,27].…”

“…The reduction in the density of homopolar bonds has been proposed to explain this increase of the optical band gap in amorphous chalcogenide films [21]. Němec et al reported that PLD technique can produce amorphous thin films with different structure (in terms of different amounts of Ge-Ge or Se-Se bonds) [25]. Annealing decreased the density of Se-Se homopolar bonds, which caused increase of the optical band gap.…”

Photoinduced phenomena in thin films of chalcogenide system Ga-Ge-S: a role of oxidation

“…Such kind of structural distortions leads to slight changes of the optical absorption edge position and the refractive index (usually about 0.5 -2%) [9,10]. Moreover these photoinduced changes are typically reversible.…”