Identification of buffer and surface traps in fe-doped algan/gan hemts using y21 frequency dispersion properties

P. Vigneshwara Raja, Nandha Kumar Subramani, Florent Gaillard, Mohamed Bouslama, Raphaël Sommet, Jean Christophe Nallatamby*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The buffer and surface trapping effects on low-frequency (LF) Y-parameters of Fe-doped AlGaN/GaN high-electron mobility transistors (HEMTs) are analyzed through experimental and simulation studies. The drain current transient (DCT) characterization is also carried out to comple-ment the trapping investigation. The Y22 and DCT measurements reveal the presence of an electron trap at 0.45–0.5 eV in the HEMT structure. On the other hand, two electron trap states at 0.2 eV and 0.45 eV are identified from the LF Y21 dispersion properties of the same device. The Y-parameter simulations are performed in Sentaurus TCAD in order to detect the spatial location of the traps. As an effective approach, physics-based TCAD models are calibrated by matching the simulated I-V with the measured DC data. The effect of surface donor energy level and trap density on the two-dimensional electron gas (2DEG) density is examined. The validated Y21 simulation results indicate the existence of both acceptor-like traps at EC –0.45 eV in the GaN buffer and surface donor states at EC –0.2 eV in the GaN/nitride interface. Thus, it is shown that LF Y21 characteristics could help in differentiating the defects present in the buffer and surface region, while the DCT and Y22 are mostly sensitive to the buffer traps.

Original languageEnglish
Article number3096
JournalElectronics (Switzerland)
Issue number24
StatePublished - 1 Dec 2021
Externally publishedYes


  • AlGaN/GaN HEMT
  • Buffer traps
  • Drain current transient
  • Frequency dispersion
  • Surface traps
  • TCAD simulation
  • Y and Y parameters


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