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

Abstract

AbstractQuaternary germanium‐antimony‐selenium‐tellurium (Ge‐Sb‐Se‐Te) thin films deposited from Ge19.4Sb16.7Se63.9−xTex (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 GeaSbbSecTed 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 (Se2+, GeaSb+ (a = 1–4), and GeSec+ (c = 1, 2)) and new (Ge+ and SbbTe+ (b = 1–3)) clusters may indicate that some of the structural features of the films (Ge2Se6/2 and Se2Sb‐SbSe2) were replaced by (GeSe4−xTex and SbSe3−xTex) 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 Sb3+ 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.