Date of Completion

Spring 5-8-2015

Thesis Advisor(s)

Helena Silva; Ali Gokirmak

Honors Major

Electrical Engineering

Abstract

Ge2Sb2Te5 nano line cells cycled most successfully between the amorphous and crystalline states when a continuous SET-RESET pulse was applied with a square 20 ns amorphization pulse and a 3.5 μs crystallization pulse. The crystalline pulse had a 1 μs ramped incline and a 2 μs ramped decline. The resistance window between the SET and RESET states drastically declined if the amplitude of the SET-RESET waveform was not increased. In resistance drift measurements, the device cycled 10 times had a higher stabilized crystalline resistance than the device only cycled once. These results suggest that cycling a device multiple times disturbs the wires so that the stable crystalline resistance is higher than that of the devices which are only set once (or not cycled at all). An RC time delay was observed when an AC signal was applied to amorphized wires with a 1 MΩ termination resistance. It is hypothesized that two parasitic Schottky diodes are forming between the contact metal and the semiconductor material and causing the unusual charging and discharging. A new model of the experimental set-up has been created to account for this phenomenon.

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