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Laser desorption time‐of‐flight mass spectrometry of atomic switch memory Ge 2 Sb 2 Te 5 bulk materials and its thin films
Author(s) -
Houška Jan,
PeñaMéndez Eladia Maria,
Kolář Jakub,
Přikryl Jan,
Pavlišta Martin,
Frumar Miloslav,
Wágner Tomáš,
Havel Josef
Publication year - 2014
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6833
Subject(s) - germanium , analytical chemistry (journal) , chemistry , reflectron , mass spectrometry , stoichiometry , thin film , mass spectrum , pulsed laser deposition , telluride , time of flight mass spectrometry , crystallography , ionization , ion , materials science , silicon , nanotechnology , organic chemistry , chromatography
RATIONALE Although the structure of atomic switch Ge 2 Sb 2 Te 5 (GST) thin films is well established, the composition of the clusters formed in the plasma plume during pulsed‐laser deposition (PLD) is not known. Laser Desorption Ionization Time‐of‐Flight Mass Spectrometry (LDI‐TOF MS) is an effective method for the generation and study of clusters formed by laser ablation of various solids and thus for determining their structural fragments. METHODS LDI of bulk or PLD‐deposited GST thin layers and of various precursors (Ge, Sb, Te, and Ge‐Te or Sb‐Te mixtures) using a nitrogen laser (337 nm) was applied while the mass spectra were recorded in positive and negative ion modes using a TOF mass spectrometer equipped with a reflectron while the stoichiometry of the clusters formed was determined via isotopic envelope analysis. RESULTS The singly negatively or positively charged clusters identified from the LDI of GST were Ge, Ge 2 , GeTe, Ge 2 Te, Te n ( n = 1–3), GeTe 2 , Ge 2 Te 2 , GeTe 3 , SbTe 2 , Sb 2 Te, GeSbTe 2 , Sb 3 Te and the low abundance ternary GeSbTe 3 , while the LDI of germanium telluride yielded Ge m Te n + clusters ( m = 1–3, n = 1–3). Several minor Ge‐H clusters were also observed for pure germanium and for germanium telluride. Sb n clusters ( n = 1–3) and the formation of binary TeSb, TeSb 2 and TeSb 3 clusters were detected when Sb 2 Te 3 was examined. CONCLUSIONS This is the first report that elucidates the stoichiometry of Ge m Sb n Te p clusters formed in plasma when bulk or nano‐layers of GST material are ablated. The clusters were found to be fragments of the original structure. The results might facilitate the development of PLD technology for this memory phase‐change material. Copyright © 2014 John Wiley & Sons, Ltd.