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6CCVD Research

Investigation of Wide- and Ultrawide-Bandgap Semiconductors From Impact-Ionization Coefficients

At a Glance

Section titled ā€œAt a Glanceā€
MetadataDetails
Publication Date2020-08-03
JournalIEEE Transactions on Electron Devices
AuthorsFranklin Nouketcha, Y. Cui, Aivars J. Lelis, Ronald Green, C. Darmody
InstitutionsUniversity of Maryland, College Park, DEVCOM Army Research Laboratory
Citations22

Abstract

Section titled ā€œAbstractā€

We survey impact-ionization coefficients for silicon, wide bandgap semiconductors (gallium nitride and 4H-silicon carbide), and ultrawide-bandgap semiconductors (aluminum gallium nitride, beta-gallium oxide, and diamond). We employ a custom genetic algorithm to fit those existing coefficients into a modified Thornber model. This fitting process leads to an estimation of material properties, such as ionization energy, optical-phonon energy, and mean free path. After evaluating electric-field profiles by solving the Poisson equation, we use the impact-ionization integral to fundamentally calculate the breakdown voltage and the critical field of various p-i-n structures. This work captures how the doping concentration and the thickness of the drift layer shape the breakdown voltage as well as the critical field achievable with a given material. It is observed that a wider bandgap is not the sole requirement for the achievement of a higher breakdown voltage. Impact-ionization coefficients and dielectric constants are additional material properties that influence the calculation of the breakdown voltage. The performance limits of diamond are found to be surprisingly poor for its large bandgap. AlxGa1-xN and $\beta $ -Ga2O3 have almost the same performance limits, but it is observed that aluminum gallium nitride can outperform gallium oxide at high voltage if its background doping (doping floor) can be reduced.

Tech Support

Section titled ā€œTech Supportā€

Original Source

Section titled ā€œOriginal Sourceā€

References

Section titled ā€œReferencesā€
  1. 2012 - Measurement of impact ionization coefficients in GaN

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