Nanoscale conductive pattern of the homoepitaxial AlGaN/GaN transistor

A. Pérez-Tomás, G. Catalàn, A. Fontserè, V. Iglesias, H. Chen, P. M. Gammon, M. R. Jennings, M. Thomas, C. A. Fisher, Y. K. Sharma, M. Placidi, M. Chmielowska, S. Chenot, M. Porti, M. Nafría, Y. Cordier

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10 Citations (Scopus)


The gallium nitride (GaN)-based buffer/barrier mode of growth and morphology, the transistor electrical response (25-310 C) and the nanoscale pattern of a homoepitaxial AlGaN/GaN high electron mobility transistor (HEMT) have been investigated at the micro and nanoscale. The low channel sheet resistance and the enhanced heat dissipation allow a highly conductive HEMT transistor (Ids>1 A mm-1) to be defined (0.5 A mm-1 at 300 C). The vertical breakdown voltage has been determined to be ∼850 V with the vertical drain-bulk (or gate-bulk) current following the hopping mechanism, with an activation energy of 350 meV. The conductive atomic force microscopy nanoscale current pattern does not unequivocally follow the molecular beam epitaxy AlGaN/GaN morphology but it suggests that the FS-GaN substrate presents a series of preferential conductive spots (conductive patches). Both the estimated patches density and the apparent random distribution appear to correlate with the edge-pit dislocations observed via cathodoluminescence. The sub-surface edge-pit dislocations originating in the FS-GaN substrate result in barrier height inhomogeneity within the HEMT Schottky gate producing a subthreshold current.

Original languageEnglish
Article number115203
Issue number11
Publication statusPublished - 20 Mar 2015


  • HEMT
  • MBE
  • high mobility transistor
  • homoepitaxial GaN
  • nanoscale


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