NANOSCALE DEVICE MODELING FROM MOSFETS TO MOLECULES A Thesis

Damle Prashant Subhash Ph D Purdue University May Nanoscale device modeling from MOSFETs to molecules Major Professor Supriyo Datta This thesis presents a rigorous yet practical approach to model quantum transport in nanoscale electronic devices As conventional metal oxide semiconductor devices shrink below the one hundred nanometer regime quantum mechanical e ects are be ginning to play an increasingly important role in their performance At the same time demonstration of molecular switches has generated considerable interest in the emerging eld of molecular electronics Understanding electronic transport in nano devices and molecules using rigorous physics based models is critical in order to design and fabricate such structures Our approach is based on the non equilibrium Green s function NEGF formalism which is rapidly gaining acceptance as the method of choice to treat quantum transport in nanostructures We use our method to treat a few nanoscale devices of current interest namely a dual gate silicon nanotransis tor e ective mass model a three terminal molecular device semi empirical atomic orbital model and two terminal molecular wires rigorous ab initio atomic orbital model The results provide useful insights into the underlying physics in these de vices Several important features like charge transfer self consistent band lineup I V characteristics voltage drop etc are analyzed and explained