On the growth and composition of conductive filaments on the surface of As–Se–Te bulk glassy semiconductors

A memory (lock-on) phenomenon was observed in the semiconducting glasses belonging to the As–Se–Te system, and this phenomenon was studied through electrical, calorimetric, and x-ray diffraction methods. The structural characteristics were also correlated to the time it takes to reach the memory state. The growth process in composition As_0.40Se_0.30Te_0.30 exhibited a dependence on electrode polarity in such a way that it began at the positive electrode and finished at the negative one. The growth speed of the conductive filament was found to be approximately 22μm s⁻¹. The crystalline nature of the lock-on filament was confirmed, and the peaks corresponding to the x-ray diffraction pattern of the surface of a sample of composition As_0.45 Se_0.10Te_0.45, partially covered by filaments, correspond to monoclinic As₂Te₃. The memory effects found agree with those predicted through Ovshinsky's criterion, as the average coordination numbers for the noncrystalline structures of the alloys analyzed are 2.4 and 2.3, respectively.