Electrical Switching and Optical Bandgap Studies on Quaternary Ag-Doped Ge–Te–In Thin Films

Abstract

Amorphous Ge ₁₅ Te _{80_x} In ₅ Ag _x (6≤ x ≤24) thin films prepared in sandwich geometry exhibit memory switching behavior unlike the bulk sample that has shown both threshold switching for less current (1-2 mA) and memory switching for current greater than 2 mA. As anticipated, the threshold voltage of Ge ₁₅ Te _{80_x} In ₅ Ag _x (6≤ x ≤ 24) thin films is found to be lower as contrast to those of bulk counterparts. The compositional dependence of amorphous system shows an extensive plateau in the range of 6 x 12 which literally stands for the intermediate phase after which there is a drastic increase in the threshold field. Shifted rigidity percolation threshold has also been confirmed from the compositional dependence of threshold field of amorphous Ge ₁₅ Te _{80_x} In ₅ Ag _x thin films. In addition, the optical bandgap of a-Ge ₁₅ Te _{80_x} In ₅ Ag _x thin-film sample has been reckoned considering absorption spectra, and the compositional dependence has been described based on average bond energy of the system.