Paper
8 March 2014 Effect of electron density on cutoff frequency of III-N HFETs
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Abstract
Advances in frequency performance of heterostructure field-effect transistors (HFETs) are discussed in terms of dissipative processes. The conditions for fastest dissipation coincide reasonably well with those for fastest operation and slowest device degradation. The correlation has its genesis in dissipation of the hot-phonon heat accumulated by non-equilibrium optical phonons launched by hot electrons. The hot-phonon heat causes defect formation and additional electron scattering in a different manner as compared with the effects due to conventional heat accumulated by acoustic phonons. The desirable ultrafast conversion of hot phonons into acoustic phonons is assisted by plasmons as demonstrated through measurement of hot-phonon lifetime. Signatures of plasmons have been also resolved in hot-electron transport, transistor frequency performance, phase noise, and device reliability. The plasmon-assisted ultrafast dissipation of hot-phonon heat explains the known necessity for application a stronger negative gate bias to a channel with higher as-grown electron density.
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Arvydas Matulionis and Hadis Morkoç "Effect of electron density on cutoff frequency of III-N HFETs", Proc. SPIE 8986, Gallium Nitride Materials and Devices IX, 89861D (8 March 2014); https://doi.org/10.1117/12.2036914
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KEYWORDS
Phonons

Gallium nitride

Ultrafast phenomena

Heterojunctions

Scattering

Acoustics

Transistors

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