Germanium‐antimony‐selenium‐tellurium thin films: Clusters formation by laser ablation and comparison with clusters from mixtures of elements

Abstract

Quaternary germanium-antimony-selenium-tellurium (Ge-Sb-Se-Te) thin films deposited from Ge 19.4 Sb 16.7 Se 63.9−x Te x (x = 5, 10, 15, and 20) glass-ceramics targets by radio frequency magnetron sputtering were studied using laser ablation quadrupole ion trap time of flight mass spectrometry. Binary, ternary, and quaternary Ge a Sb b Se c Te d clusters were formed and their stoichiometry was determined. By comparison of the clusters obtained from quaternary Ge-Sb-Se-Te thin films and those from ternary Ge-Sb-Te materials, we found that Ge-Te species are not detected from the quaternary system. Furthermore, Ge-Se and Se-Te species are missing in mass spectra generated from Ge-Sb-Se-Te thin films. From the Ge-Sb-Se-Te thin films, 16 clusters were detected while ternary Ge-Sb-Se glasses yielded 26 species. This might be considered as a signal of higher stability of Ge-Sb-Se-Te thin films which is increasing with a higher content of Te. The missing (Se 2 + , Ge a Sb + (a = 1-4), and GeSe c + (c = 1, 2)) and new (Ge + and Sb b Te + (b = 1-3)) clusters may indicate that some of the structural features of the films (Ge 2 Se 6/2 and Se 2 Sb-SbSe 2 ) were replaced by (GeSe 4−x Te x and SbSe 3−x Te x ) ones.In addition, when comparing the stoichiometry of clusters formed from Ge-Sb-Se-Te thin films with those from the mixtures of the elements, only Sb 3 + and SbSe + were observed in both cases. The knowledge gained concerning clusters stoichiometry contributes to the elucidation of the processes proceeding during plasma formation used for the chalcogenide thin films deposition.