Scanning-tunneling-microscope modifications of Cu(Ag)-chalcogenide glasses

Chalcogenide glasses containing Cu and Ag were investigated using a scanning tunneling microscope (STM). Cu-As-Se and Ag-As-Se glasses exhibited different phenomena. When voltages applied to STM tips were low (\V\ less than or equal to 1 V), tunneling spectra in Ag-As-Se changed with scan speed of the tip voltages, while such a feature was not observed in Cu-As-Se. At high voltages (\V\ greater than or equal to 3 V), geometrical surface modifications appeared in both glasses, but the shapes were different. In Ag-As-Se hills or holes were created, and in Cu-As-Se deformations were induced under negative tip voltages. Origins of these observations are discussed. (C) 1998 Elsevier Science B.V. All rights reserved.