Title of Submission
A Study of the Electrical Conduction Mechanisms of Bilayer Phase-Change Memory Devices Over the Temperature Range of 5 K to 340 K
Electrical and Computer Engineering, PhD
Major Advisor Name
Type of Submission
In this work, three phase change memory (PCM) devices using layered chalcogenide materials, GeTe/SnTe, Ge2Se3/SnTe, Ge2Se3/SnSe, and one single material layer device comprised of Ge2Sb2Te5 (GST) were fabricated and electrically characterized. The GeTe and Ge2Se3 bilayer devices have previously demonstrated lower threshold voltages and improved cycling reliability compared to the GST-based devices . Part of this improvement was attributed to better mechanical electrode contact as well as electrical band alignment between the top electrode and the device material layers. To further explore the mechanisms responsible for the observed functional improvements, in this work the conduction mechanisms of all four device types were investigated using quasi-static DC I-V curve measurements over the high resistance state to the low resistance state, in the temperature range of 5 K to 340 K. Mechanisms investigated were Schottky emission, Poole-Frenkel emission, Fowler-Nordheim mechanism, direct-tunneling, space-charge limited conduction (SCLC), hopping, and extended states conduction.