Polarization engineering in GaN power transistors

Tetsuzo Ueda*, Tomohiro Murata, Satoshi Nakazawa, Hidetoshi Ishida, Yasuhiro Uemoto, Kaoru Inoue, Tsuyoshi Tanaka, Daisuke Ueda

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


This paper reviews novel design of epitaxial structure for GaN power transistors to reduce the on-state resistance and to increase the breakdown voltage. It takes advantages of the fixed charges at the interfaces caused by the material's inherent polarization, and thus it can be called as polarization engineering. Both AlGaN/GaN superlattices and polarizationmatched InAlGaN quaternary alloy effectively reduce the onstate resistance by using them as capping layers over AlGaN/GaN combined with the recessed-gate structure. These capping layers successfully eliminate the electron depletion which is caused by the balancing of the fixed charges. The series resistance across the interface is fully reduced so that these capping layers enable low on-state resistance. Proposed natural super junction (NSJ) model well explains the fact that the breakdown voltages of AlGaN/GaN hetero-junction field effect transistors (HFETs) are increased by the extension of the gate and drain spacing. The model assumes that the heterojunction can act an insulator since the polarization induced charges are always balanced at the top and the bottom surfaces. Taking advantages of the model, the fabricated multi-channel AlGaN/GaN diode with dual-recessed structure exhibits high breakdown voltage of 9400V with low on-state resistance of 52mωcm2, which reaches the predicted performance limit of GaN. The presented polarization engineering is very promising for future improvement of the device performances.

Original languageEnglish
Pages (from-to)1735-1739
Number of pages5
JournalPhysica Status Solidi (B) Basic Research
Issue number7
StatePublished - 1 Jul 2010


  • Electrical properties
  • III-V semiconductors
  • Semiconductor devices

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