Effect of ion irradiation on the optical properties of Ag-doped Ge2Sb2Te5 (GST) thin films.

• Ag9+ heavy ions (120 MeV) are irradiated on pure and Ag doped Ge 2 Sb 2 Te 5 (GST) thin films. • Phase transition is observed with Ag9+ ion irradiation which crystallizes amorphous GST thin films at higher fluence. • Ag doping suppress crystallization in ion irradiated GST thin films. Structural and optical study of pure and Ag-doped Ge 2 Sb 2 Te 5 (GST) thin films after swift heavy ion irradiation, is presented. In the present work, we have used 120 MeV Ag9+ ions for irradiation using various ion fluence. Structural properties were investigated using XRD and Raman spectroscopy. Undoped films were found to crystallize at the highest fluence (1 × 10 13 ions/cm2). Ag doping is found to suppress crystallization. From UV-Vis-NIR spectra, a decrease in optical bandgap was observed due to ion irradiation on these films. Observed results are explained on the basis of crystal nuclei, which results in crystallization and observed structural changes. Changes in defect chemistry are proposed to be responsible for the observed optical changes. [ABSTRACT FROM AUTHOR]