Low-Dispersion, High-Voltage, Low-Leakage GaN HEMTs on Native GaN Substrates

Muhammad Alshahed, Lars Heuken, Mohammed Alomari, Ildikó Cora, Lajos Tóth, Bèla Pècz, Clemens Wächter, Thomas Bergunde, Joachim N. Burghartz

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4 Citations (Scopus)


In this paper, the advantages of GaN high electron mobility transistors (HEMTs) grown on native GaN over GaN/Si or GaN/sapphire substrates are investigated and correlated with epitaxial material quality. Transmission electron microscopy plan-view and cross-sectional analyses of GaN/GaN reveal dislocation densities below 1 × 10 6 cm-2, which is at least three orders of magnitude lower than that of GaN/Si or GaN/sapphire. In the case of GaN/Si, the dislocations not only originate from the substrate/nucleation layer interface, but also the strain relief and isolation buffer stacks are main contributors to the dislocation density. GaN/GaN HEMTs show superior electrical and thermal performance and feature three orders of magnitude lower OFF-state leakage. The current collapse (also referred to as current dispersion or R ON-increase) after stress bias is less than 15% compared with 50% in the case of GaN/Si. A 2% drop of the ON-state current due to self-heating in dc operation when compared with 13% and 16% for GaN/Si and GaN/sapphire, respectively. The GaN/Si thermal performance becomes comparable to that of GaN/GaN only after substrate removal. Therefore, GaN/GaN provides high ON-state current, low OFF-state leakage current, minimal current collapse, and enhanced thermal power dissipation capability at the same time, which can directly be correlated with the absence of high dislocation density.

Original languageEnglish
Pages (from-to)2939-2947
Number of pages9
JournalIEEE Transactions on Electron Devices
Issue number7
Publication statusPublished - Jul 2018



  • Bulk GaN
  • GaN high electron mobility transistor (HEMT)
  • current collapse
  • dynamic R
  • leakage currents
  • power semiconductor devices
  • power transistors
  • self-heating
  • semiconductor device reliability
  • thermal power dissipation
  • thermal resistance
  • threading dislocations

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

Cite this

Alshahed, M., Heuken, L., Alomari, M., Cora, I., Tóth, L., Pècz, B., Wächter, C., Bergunde, T., & Burghartz, J. N. (2018). Low-Dispersion, High-Voltage, Low-Leakage GaN HEMTs on Native GaN Substrates. IEEE Transactions on Electron Devices, 65(7), 2939-2947. https://doi.org/10.1109/TED.2018.2832250