EE PhD oral examination - Arunanshu Roy, March 14, 1 PM, CISX-Aud.

Arunanshu Roy amroy at
Tue Mar 13 13:12:05 PDT 2012

Title: Tunneling contacts and spin transport in novel devices

Arunanshu Roy, Department of Electrical Engineering
Advisor: Prof. Krishna Saraswat

Date: Wednesday, March 14th 2012
Time: 1 PM (Refreshments at 12:45 PM)
Location: Paul Allen Auditorium (Formerly CISX-101) (

While the continued scaling of transistors faces severe limitations, novel devices incorporating new materials, new transport mechanisms and new state variables are emerging as a strong contender for future logic and memory. This talk will describe our work on the modeling and simulation of three such devices
1) Metal-insulator-semiconductor (MIS) contacts to achieve low contact resistance 
We have developed a contact resistance simulator for MIS structures and made quantitative predictions of the achievable contact resistance using different insulator materials. We predict TiO2 to be a suitable interface material for and experimentally verify the Fermi level depinning effect using TiO2.
2) Spin MOSFETs using ferromagnetic source/drain contacts
We have developed an efficient framework to simulate spin transport in semiconductors coupled with a tunneling model for spin injecting contacts. We demonstrate the important effects of electric fields, the voltage dependence of magnetoresistance (MR)  and the effect of parameters such as tunnel oxide thickness, semiconductor channel length and doping density on MR.	
3)Magnetic tunnel junctions using spin selective MgO tunneling barriers
We have developed our own implementation of the extended Huckel theory (EHT) atomistic simulation coupled with non-equilibrium Green’s function (NEGF) formalism for transport. Through these EHT-NEGF simulations we demonstrate the reduction of magnetoresistance due to Fermi level pinning. An approximate approach for the simulation of CoFe alloy electrodes is developed. 

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