MÖSSBAUER STUDY OF RESISTIBILITY TO OXIDATION OF THIN FILMS Sn1-xPbxTe AND Sn1-xPbxSe
Le Journal de Physique Colloques
A wide use of thin films of compounds A~B " and their aqlogues in technique requires thorough investigation of their physical and chemical properties. One of these is the resistibility to oxidation of the thin films. The initial film samples on mica backings were sedimented out of the gas dyna-mica1 flow of vapour in double quasiclosed volume [ I ] , The thickness of the films was 8-20 mkm. Oxidation of the samples was performed in air in the temperature range 423-873 K from 6 to 180 minutes.
... e measurements were taken at room temperature using ~al'~~n0 source. The 3 thickness of the absorbers was 10-15 2 %/em of natural tin. 'The measurements of the l\Iossbauer spectra showed that in the samples Snl-xPbxTe under oxidation two forms of tin appearthe initial and Sn02. When oxidizing the films S n l , P b , S e , 3 forms of tin appear: the initial, Sn02 and Sn506Se4 ( fig. 1 ). For identification of Fig. 1 -~~ossbauer spectrum of the oxidized system of the thin films Snl-xPbxSe decomposed into the components 1 -Sn02; 2 -Sn506Se4; 3 -SnSe, the latter form the results of v r o r : : 123 and the results of the resolution of the measured spectra into coniponents were used (the program for the least square fit of the measured TIossbauer spectra vms used). The quantity of every chemical form of tin in the sample investigated was determined by comparison of normalized areas of the corresponding Xossbauer lines. all investigations were performed in four stages. In the first stage to determine the threshold, of oxidation the temperature was changed at the fixed heating time (3 hours). The results are presented in table 1 . Table 1 Percentage of the oxidized forms of tin depending on the oxidation temperat~u'e (thickness of the films 15 mlan, duration of the oxidation 3 hours). -----Initial Oxidized Oxidation sample form of temperatme K tin 420 570 670 770 PbO.lSnO. 9! ! ! e Sn02 0 0 0 100 --p~~--~ ---In the second stage the dependence of the amou~t of Sn02 on the time of heating was investigated at the fixed temperature. The results are presented in fig, 2. In the third stage the heating tempex8,ture was fixed and the dependence of t'ne oxidation rate on the -thickness of the film was investigated. The results axe presented in fig. 3 . In the fourth stage at the fixed heating teixperature the time Article published online by EDP Sciences and available at http://dx.