Investigation of homo-junction InGaAs band-to-band tunneling diodes
Abstract
Band-to-band tunneling transistors (TFETs) are very promising devices to replace the conventional MOSFETs at the end of the semiconductor road map and to reduce the power consumption of integrated circuits due to their less than 60 mV/dec subthreshold swing. By investigating band-to-band tunneling (BTBT) diodes with a vertically grown p-n interface, it is possible to test the tunneling properties of a given material and its potential as TFETs. Homo-junction InGaAs p-n tunneling diodes lattice matched to InP were investigated using a full-band and atomistic quantum transport approach based on the tight-binding model and the Non-equilibrium Green’s Function (NEGF) formalism. Experimental devices fabricated at Penn State University and at Notre Dame University were considered. A careful investigation of the available experimental data, especially the turn-on of the thermionic diode current suggested that band gap narrowing (BGN) plays an important role in heavily-doped BTBT diodes. Hence, this effect is included in the tight-binding model by altering its parameters according to the Jain-Roulston model, which calculates conduction and valence band shifts of n- and p- side of the diodes as function of doping concentration. BGN is then taken into account in the quantum transport simulations, and its effect on the current-voltage characteristics of the considered devices is analyzed. A good agreement with the available experimental data is obtained, both in the Zener and in the NDR side of the diodes. Future inclusions of electron-phonon scattering will help improve the remaining discrepancy between the experimental and simulation results in the valley current region.
Degree
M.S.E.C.E.
Advisors
Klimeck, Purdue University.
Subject Area
Electrical engineering
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