Toward understanding positive bias temperature instability in fully recessed-gate GaN MISFETs

Tian-Li Wu, Jacopo Franco, Denis Marcon, Brice De Jaeger, Benoit Bakeroot, Steve Stoffels, Marleen Van Hove, Guido Groeseneken, Stefaan Decoutere

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


In this paper, fully recessed-gate GaN MISFETs with two different gate dielectrics, i.e., plasma-enhanced atomic layer deposition (PEALD) SiN and ALD Al2O3 gate dielectric, are used to study the origin of positive bias temperature instability (PBTI). By employing a set of dedicated stress-recovery tests, we study PBTI during the stress and relaxation. Hence, a defect band model with different distributions of defect levels inside the gate dielectric is proposed, which can excellently reproduce the experimental data and provide insightful information about the origin of PBTI in GaN MISFETs. The results indicate that the serious PBTI in the device with PEALD SiN is mainly due to a wide distribution of defect levels (σ ∼ 0.67 eV), centered below the conduction band of GaN (EC -0.05 eV), and can be easily accessed by the channel carriers already at a low-gate voltage. On the other hand, ALD Al2O3 gate dielectric shows a narrower distribution of defects (σ ∼ 0.42 eV), which are far from the conduction band of GaN (EC +1.15 eV). This observations explain the improved PBTI reliability observed in devices with ALD Al2O3.

Original languageEnglish
Article number7440814
Pages (from-to)1853-1860
Number of pages8
JournalIEEE Transactions on Electron Devices
Issue number5
StatePublished - 1 May 2016


  • GaN-on-Si
  • positive bias temperature instability (PBTI)
  • recessed gate
  • VTH hysteresis.

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