Speaker: Prof. Ali Gokirmak, University of Connecticut
Location: CEPSR 414 for 3-4pm, 10/21
Title: Tunneling, Filamentary Conduction and Thermoelectricity at Small Scales, and Phase Change Memory
Abstract: Tunneling is utilized in flash memory, magnetic tunnel junctions, Josephson Junctions and tunnel diodes and plays a significant role in resistive memory (RRAM) and phase change memory (PCM). Variations in the tunnel barriers lead to filamentary currents. High local current densities can lead to local heating and changes in trapped charges as well as changes in composition. Strong thermal gradients and high current densities lead to significant thermoelectric contributions.
PCM is a non-volatile electronic memory technology that utilizes the resistivity contrast of amorphous and crystalline phases of glassy materials to store information. PCM devices are switched from one phase to the other by self-heating (T = 300 K ~ 1000 K) using electric current in a ~ (10 nm)3 volume, where devices experience high electric fields (E ~ 107V/m), extreme current densities (107 A/cm2) and thermal gradients (~50 K/nm). Critical feature size of mass-produced PCM devices are ~ 3nm in 2025 and are continuing to scale.
In this discussion we will try to clarify some of the misconceptions related to tunneling and introduce the interesting behavior we observe at nanometer and micrometer length scales.
Bio: Ali Gokirmak has received BS in Electrical Engineering and BS in Physics from University of Maryland at College Park in 1998, and PhD in Electrical & Computer Engineering from Cornell University in 2005. He is a faculty member in Electrical & Computer Engineering at University of Connecticut since 2006.