NEGF simulation of electron transport in resonant tunneling and resonant interband tunneling diodes

Arun Goud Akkala, Purdue University

Abstract

The challenges due to continuous scaling of CMOS has prompted research into alternative structures for future logic devices that are capable of high speed operation with reduced power consumption. One such contender in the emerging devices category, the Resonant tunneling diode (RTD), has attracted considerable interest due to its low voltage operation, THz capabilities and negative differential resistance. RTDs operate on the principle of quantum mechanical tunneling of electrons through a potential barrier into quantized well states resulting in resonances in the transmission characteristics. Due to the quantum mechanical nature of the tunneling process, quantum transport simulation models are needed to describe RTD characteristics. In this work, a simulation tool based on the Non-Equilibrium Green's Function formalism using effective mass approach has been developed to study GaAs/AlGaAs RTD characteristics. Scattering in the emitter reservoir has been treated in an approximate manner to ease computational burden. However the room temperature peak to valley current ratio (PVR), which is the figure of merit for RTDs, has to be improved in order to make them a suitable candidate for digital applications. Resonant Interband Tunneling diodes (RITD) are capable of achieving higher PVRs by reducing valley current. A multiband model is required for RITDs since both conduction and valence band play a role. An sp3s* spin-orbit based tight binding model along with an NEGF based transport solver has been used to study a coherent InAs/AlSb/GaSb RITD and the simulated IV shows a high PVR of 50.

Degree

M.S.E.C.E.

Advisors

Klimeck, Purdue University.

Subject Area

Electrical engineering|Condensed matter physics|Nanotechnology

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