CRYSTALLIZATION OF AMORPHOUS SB-SE THIN-FILMS

The crystallization processes of amorphous Sb-Se thin films were studied in detail mainly by calorimetry and mean time for crystallization at room temperature was estimated. Amorphous Sb100-x-Se(x) thin films (X = 20 approximately 65 at%) were deposited on glass plate, and Polymethyl-Methacrylate (PMMA) substrate using two-point electron beam deposition and RF magnetron sputtering techniques. The crystallization process of amorphous Sb-Se thin films have been investigated by X-ray diffraction (XRD) differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). An activation energy for the crystallization is estimated by Kissinger's plot and Johnson-Mehl-Avrami (J.M.A) equation. The crystallization temperatures were found to be proportional to the Se concentration (Se less-than-or-equal-to 60 at%) and those of Sb40Se60(Sb2Se3) and Sb67Se33 (Sb2Se) films were estimated to be 220-degrees-C and 195-degrees-C respectively by DSC measurements (heated at a scanning rate of 10-degrees-C/min). An activation energy for the crystallization in an Sb67Se33 (Sb2Se) film is estimated to be (2.85 +/- 0.02) X 10(5) J / mol by Kissinger's plot (from the analysis of the DSC data on the continuous heating) and (2.78 +/- 0.02) x 10(5) J / mol by J. M.A equation (from the analysis of the DSC data on the isothermal annealing) , and its reaction order is n = 5 approximately 6 and the frequency factor is v = 1.61 x 10(29) (s-1) . It was concluded that the amorphous Sb67Se33(Sb2Se) thin film is sufficiently stable at room temperature for practical use. The mean time for 10% crystallization was estimated to be about 100 years at 100-degrees-C. The structure of the crystalline Sbr67Se33(Sb2Se) transformed from the amorphous phase was found to be monoclinic, which does not correspond to any known compounds in the Sb-Se system.